Port Matching, Porting And Trenching Two-Stroke Engine Cases

[@rcracer641]

One thing to keep in mind, when you cut away from the crank case and increase volume, when the piston comes down to pressurize the crankcase, it can not create as much pressure to push into the cylinder with.

[@rippn6124]

Stuff crank w cork and epoxy. Speed secrets of a16yr

[@gislemark79]

If your pipe is working as it should the volume in the crank case doesn't matter. The pipe will suck the mixture for you.

[@kingcosworth2643]

@@rippn6124 Rebalance your rotating assembly after doing such a thing.

[@jeffreyhagelin3672]

@@gislemark79 That absolutely is not true.

[@jeffreyhagelin3672]

@@rippn6124 No thank you.

[@skiivisualz5700]

i have a gilera runner 1999 50cc ....i had upgraded to a 70cc as for my first ever engine build...the next time i do pull apart my engine i will be port matching and smooothing ....thankfully im a very very experienced fabricator/tig welder and have weld repaired multiple engine blocks with cracks...can't wait to try this!

[@probegt75]

I have a buddy who did this with with a 70cc 2fast cylinder and the power it makes is insane. The information in this video is invaluable.

[@Mike-uh2gw]

Leave a rough finish on areas where fuel / air mix is travelling and polish exhaust till it's shiny. Rough surfaces help with atomization of your mixture and you want the exhaust to have the least amount of friction you can deliver.

[@tonyanimal1]

If you dont mind me making a suggestion. I actually recommend the double cut carbide/tungsten burrs WITH a soft wax instead of WD-40. It will unclog the flutes, and makes for a very smooth cutting process and prevents grabbing of your work piece. Just insert your cutting bit into the wax while still spinning your cutting tool. Repeat the process frequently. Youll notice the difference in ease of your cut, no vibration or turbulence.

[@RyanMcIntyre]

He's removing huge amounts of aluminum, you want a single cut, spiral, or high-helix burr on aluminum always when reshaping aluminum.

[@morbidchaos254tx4]

As a machinist, I can't believe I've never thought of that. Thank you lol

[@kingcosworth2643]

When you use JB Weld or Devcon on cases or heads, heat the item in the oven to about 90degC before you put the glue in, it will dry in a matter of minutes, but more importantly this is done to give the strongest adhesion to the aluminium.

[@truethought369]

When removing alloy from the cases, remember you will also be lowering the primary compression. Look up Tods tuning for BSA Bantams. Tod used to fit crankcase stuffers, to compensate for metal removed from ports. Also renew crankshaft oil seals.

[@WireWeHere]

A squirt of bluing into a 2 stroke spun externally can reveal the major patterns in flow. Testing the reeds to identify the relative crank position is possible with the tiny vision equipment and data acquisition available now plus a little ingenuity. 2 Stroke Stuffing has been very interesting to follow in his quest for the illusive 50cc holy grail. Peace.

[@shaunsurname8275]

2:59 brilliant, I've had a hallway chair problem for a long time. Got my dremel out, 3 days later it's ground away to only a tiny piece of wood with enough clear through way and direct path down my hallway. Thanks so much!

[@xtremluck6260]

This video was awesome! The amount of detail and information was far more then I expected. Now I don’t have butterflies in my stomach thinking about porting my own. There was a segment were you showed two casings where one had sharp edges with no lead in angle. The other had rounds and drafts as we call them in the biz. The one with sharp edges was done by someone who doesn’t understand or has a clue of production casting methods. While the casting with rounds was done by someone who did the design by industry standards and understands the added benefits when designed into the part.

[@buildingracingvideos4714]

On aluminum I used 60 or 80 grit sanding cones. They're fast enough for me and slow enough to keep me from destroying case's or ports. They work really good on 4 stroke ports

[@MrRoger13th]

Wish i had youtube with this content back in 1998 when i was tuning my piaggio typhoon 70cc. Well me and my friends were selflearning back then with all the pros and cons hahaha. Nice video!

[@ianrushsmoustache2282]

MrRoger13th in 1997 I got a brand new yellow piaggio zip sp , bloody loved it just with a Leo vince exhaust it did 55mph . I sold it as soon as turned 17 and got a car I've been trying to find another for the last 5 years or so 🤣

[@romper4444]

WOW that's gotta be the best porting DIY guide I've ever seen for bottom ends on the Internet 😮

[@thadeusdeckers2082]

Pretty sure this is the best porting video available !

[@runningbear211]

Every one of his videos a extremely informative and in depth

[@jamest.5001]

It's like porting heads, only with the head cut in half! Haha. Great video, you got me looking for a deal on a 2T!

[@Idiot1477]

They're alot of fun to tinker on for SURE

[@ttrcaster]

I always screwed in some small screws under the porthole filling If if comes loose, wel you know Cilinder skirts needs some work too If they interrupt flow They don’t need to be that big Same for the piston Lots of weight and skirts can be removed 5 gram removal on a piston is huge increase in move up and down The lighter the piston the better The best vid on porting Top

[@thedownhillerboy]

It sure is both a helpful and interesting video that gives out an accurate picture of what needs to be done and how when porting and trenching 2-stroke engine block👌🏻.Being an organized/structured guy myself, it's pretty clear that all the steps of the process have been really well layed out and explained since these are all delicate operations that offer little to no room for mistakes. Enjoyed a lot watching this as I feel I've learned immensely without having had the opportunity to do it in real life so far,👍🏻🙋🏻‍♂️.

[@49ccscoot]

Thank you!

[@DirectCurrent4u]

@@49ccscoot Super nice work my friend! This really brought my Minarelli (47cc) to life! 👍

[@ahole5407]

Great video. Clear and to the point. Just so the kids know, "polishing" the ports is a BAD thing. The air fuel mixture will form droplets on the smooth surface due to surface tension. It should be no more than around 220 grit with a random scratch pattern.

[@kingcosworth2643]

Polish the exhaust port, this stops carbon from adhering to the port wall and dropping flow. You are correct regarding intake ports but the reason is the same as why a golf ball looks as it does, it creates turbulence at the surface allowing less edge effect (slowing of air at the surface)

[@tellrowland2370]

Shot peened ports are my personal favorite but difficult

[@hotdognr12323]

One way to minimize the risk of cracking the case is to saturate the epoxy with fiberglass strands. It's dirt cheap, and will massively increase the strength of the filler. It shouldn't be any harder to shape with burrs or sanding either.

[@ahole5407]

@@labrikorn_3299 WHAT? My God, I should be dead by now from all the fiberglass I've sanded in the past 25 years. Jeez the kids these days are afraid of everything 🤣

[@notagunfreak8146]

@@ahole5407 Yes avoiding lung cancer is dumb...

[@adamadamhoney]

Disposable ear plugs are great for sealing holes for filling, painting and even general penetrations in house floors for speaker wire etc. Especially good for small holes and pretty easy to remove even when painted.

[@Poulsen8900]

My buddy and I made an ac Yamaha jog r (Horizontal minarelli)(with malossi mhr) without the right porting for that cylinder it made 10.82 whp on the dyno. After maxing out the porting and clearing space for the reed valve it made 15.6 whp so it really adds a lot on higher end builds

[@-sickfast434]

Trenching is usually used to make room for a longing stroked crank without knowing exactly what you are trying to achieve you can open ports and cases so large that you begin to lose velocity and fuel Atomization also the crank gets its lubrication from the fuel/oil mixture so trying to redirect the flow of the mixture strait to the exchange ports via the intake is not always going to be beneficial if u lock up the crank bearing or bearings knocking down edges does increase flow but most importantly it reduces cracking.jb weld does not hold up to gas or oil well or vibration! Aluminum should be tigged

[@mattyceks380]

When i do matching work i like to make my own gasket/spacer from some 2 or 3mm thick aluminium sheet i tap the holes with the same thread as the studs i the bolt it to the cylinder and match it to the cylinder while theyre together then ill take it off and bolt to the cases that have marking fluid or a bunch of permanent marker on the base area and scribe out my lines using the matched aluminium spacer/gasket its not a quick process but it allows you to get as close to a perfect match as possible it is good for a matched gasket making template ill generally make my bolt holes in my gaskets have zero slop in the holes so my studs thread into them slightly so theres no chance of it moving and encroaching on the transfer area. I know its an old video but someone might get some value out of this information🤷

[@Smallbore2wheels]

i dont even have a 2T but man i love watching your videos. they're very educational. thanks.

[@49ccscoot]

If you'd switch over to a two-stroke you could change your name to Big Bore On One Wheel.

[@Smallbore2wheels]

@@49ccscoot i may or may not be going one wheel four-stroke soon. ill be building from scratch so it should be fun...hopefully. if things go well with that build I've been thinking about venturing into the two-stroke world.

[@franciscodieguez5187]

I really appreciate your time and experience. I am thinking about matching a 1987 Minarelli V1 engine. Not because of power or anything, I just want to do it for the experience, and maybe a bit smoother running, and this video explains all the critic points of that. Thank very much.

[@sebastianbobkowski6308]

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[@sebastianbobkowski6308]

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[@sebastianbobkowski6308]

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[@sebastianbobkowski6308]

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[@sebastianbobkowski6308]

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[@tomreyn3610]

I found this video well made. Narration was articulate with definitive terms and thought out before presentation. Lighting and video shot well. Overall, the topic was addressed and explained in terms that explained the objective. Good examples were shown and solutions addressing theory. Good Job. * I got something out of it. Confirming some ideas and building new ones.

[@49ccscoot]

Thanks for the kind words!

[@dirtriderz6881]

Excellent video. Thank you for taking the time to explain everything and edit this!

[@mathieugagne1282]

Nice work ! Have been using this technic in snowmobile application to. Works very well.

[@TheClintmeister]

I had a honda elite 49cc that I just cleaned up all the transfer ports, mostly with emery wheels. Put back togethe, the scooter would rev quicker and pulled much harder. Yes it does help "stock" motors, mostly in breathing.

[@rystdin]

This is good, i dont like the chemical metal though, i found out after testing that oktan 110 disolves these kinds of metals like acid. My headache is over after Malossi released their C-ONE / RC ONE cartridges however, no need for chemical metal in those for flow optimisation.

[@frankcrawford416]

I think the cut cases for the larger crank balance the volume of material removed by the trenching. Nice maticulous work.

[@herminigildodelacruzjr1752]

Very interesting as always hoping for more uploads from you thnx for taking the time to share your ideas

[@reapanomin899]

When workshop work actually becomes a work of art.

[@thomasdsmith7678]

Color the entire gasket surface, with the marker, then use a scribe-all or pick to make a fine, very accurate line to follow.

[@connorsmith1109]

When using jb weld to get it into spaces that are tight if you mix it on card and fold it into a v you can heat underneath with a lighter and it will pour. To flatten it out and steer it wet you finger with gob grease and you will be able to push it about without It sticking to your finger

[@pauldean8638]

Use a scribe as permanent marker rubs off when near oil . NEVER dig through cases unless you can wield it and NEVER use appoxy ,it's crap .people often forget it's in direct contact with petroleum vapourised fuel and heat .before anyone says go read up from pro's of tuning ,non use epoxy ,they weld cases ,the reason there isn't a definite book to tuning is cause all motors are different, that's why they called guides . There are port maps however and that's a top tuner producing a guide and a cutting guide to know exactly where to open up ports to

[@christophersherratt7299]

Hi i watched you video on porting What I've done in the past is When you have gone to far strip the coating of 1mm wire and with a sharp knife cut it up 1mm 2mm Lengths Before you put JB on the case stick the wire sleeve in your casing with Super Glue then put JB over the case on the smoothing out you will see the tops that you glued in if you go to far then once finished you can touch each one you see with drill bit and refill over job done ✔ HOPE this helps you 👍 😊 then put heat and oil resistance Spray paint over the work to protect it 👍

[@GTrainRx7]

Impressive amount of work for possibly little gain. Still worth doing and the video is presented in an instructive manner, thumbs up!

[@4wdglampingaustralia102]

Ahhhhh I have the 5BM engine so looks like most of the work will be done for me.. S6 street race 70cc kit.. Thanks for linking this its great info.

[@cecilandrews7479]

Will what you're doing cause poor lubrication for the crank and Rod. Therefore premature engine failure?

[@49ccscoot]

I've never had any problems. Some fill the oil holes and more aggressively block the crank area and still work fine.

[@sizzlean9459]

I've been at this for a lifetime and watched everything and read everything long after being an established top shelf Master Mechanic and I have to say that all your videos are great but this one is by far the best one out there. Everything you said is true whether the so-called ASE idiots agree or not. Polishing is a joke, see I went further because I love to punish the idiots, now steam is building up and must be released while you and I just relax, smile and enjoy life which if you have not noticed is not polished either. So as the number one lover of JB Weld I want to share a little knowledge with you. If you will mix your batch 10% light in hardener and very warm and runny and then you dump it into the place it goes letting it run over and bond and then pool and then stick your part in the freezer. When you get it really cold the curing times change exponentially. So check on it often until it is like play-doh and then rub a little oil on a sandwich baggy and put it over your jbweld and mold it with your fingers to the exact shape you want it putting it back in the freezer if it starts to thaw. Once you have it as your want it then just keep it in the freezer for at least 6 hours and at that point it will have cured to the regular 5 minute mark in which is has a hard skin. Once the skin is developed the stuff won't move any more and you can pull it out and put it in the oven to accelerate the curing time, just treat it like bread or cheese toast at about 300 degrees or whateer you want as the more heat the shorter the cure time. If you try this I promise you will grow to love it and you will soon be able to do it and actually get it cured in a much shorter time than normal. The greatest part about doing it this way is once it becomes like play-doh it won't stick to your fingers anymore and you can actually use tools on it before it is cured and soft and using the oiled plastic will leave you with a perfect plastic smooth finish. You can even assemble your stuff together and let the parts push everything out of the way with the plastic in between and when it is at the perfect consistensy you can simply use a blade to cut it and just play with this method and I promise you will love the stuff even more. Once you become expert with the frozen method you can then add extra hardener and essentially make your own quick cure so that it has a skin in about 1 1/2 hours in the freezer while the stuff underneath is still moldable and moveable. The most important part is cleaning the surface and making sure the hot mixture is runny and gets sure contact without air to the surface. You will find that it becomes as hard as steel when you get the mixtures right and I hope you get something from this rant friend. I really appreciate your work and your patience and keep it up man. The kids need to hear the truth's you speak and if they doubt or have doubts they need only look at the finished product to know you know your stuff from experience not from books or videos and that should be enough. I repeat polishing ports does not benefit anything people. Peace Sizzlean

[@stevebloke5455]

very true, polishing will make the fuel condensate back into droplets buggering up emulsification intern buggering the air fuel mix, not much chop for making power. good vid for a how to on a budget.

[@smokepeddler]

Uh...wrong!!!!! Always polish the exhaust port? If you dont know why your a complete asshat?

[@TheChucklee]

Very bad advice, expansion and contraction will weaken the epoxy structure and epoxy is supposed to cure from the inside out cured under extreme heat such as 300 will cure from the outside in, making the outside very brittle in the inside very soft

[@TheChucklee]

Anybody noticed the volume difference in the transfer Port base try using a flow bench way more important than matching at that point would be air velocity as with that big of volume difference one size going to flow way more air than the other bad news

[@johnmeurer4780]

Jb weld is not fuel resistant. It won't work as a filler for long if any of it is exposed in the port.

[@49ccscoot]

Multiple comments say that it won't, but real world use shows me that it has. I've had it crack before, but haven't had chunks of JB Weld fall out or anything. I won't claim that it's the best possible solution, but it outperforms many people's expectations. Current engine has 1.5 years of use without issue, and I've broken the crank, variator, worn out a cylinder... It doesn't have an easy life.

[@johnrobinson357]

Nice vid bet it took some time to edit all that - thanks for doing it. Started off with puch cases, ruined 2 got a little too happy on the burrs. And oh yeah jb weld is your friend. Puch cases are thin and easy to trash, but i got one with a good 70 cc kit to work well. Hard to say if anything i did made anything better - wishful thinking is best used. A bit more than twice the power, maybe 10 hp ? a reed kit with a higher compression head made it run hot. Trade off fuel ratio to keep temps down, it ran well but a fuel pig that fouled plugs a lot - better than seizing the cylinder. I had big plans for my piaggio scoot hyper 2 engine. Found some very interesting cylinders on UK scoot sites, 90 cc bolt right up kits. But past dirt bike crashes caught up with me as i knew they would, need 2 disks fused lower back and c5 neck. Pain is hellish 24/7 so riding is not gonna happen this year, i'll be lucky if i heal by new years. Took my old ke 175 out last week all done in half an hour, just hurt too much. But i can still get info and make plans - that will not pan out. Anyway, good video thanks for putting it up. Have a good

[@49ccscoot]

Thanks. Hope you can get feeling well enough to ride and wrench more before too long.

[@johnrobinson357]

@@49ccscoot Thank you. The hell has not started yet, 2 weeks i'll have some idea of what will happen. Think i'm looking at going on disability, might be a year long event. Strange thing about pain after ten years you do develop a tolerance to it. To a point only, pass that and it's just like new again. An ER doctor was telling me, you don't realize how it effects you until it's gone. Blood pressure, concentration, sleep habits are all effected you do not think about it. Happens by it self. If you look up the word stubborn - you'll see a picture of me next to it. I really have waited far too long in dealing with my spinal injuries. Pain is a powerful motivator had it not been for that, i would still be just going along with it. stupidly I am NOT going to write books here - it is what i do - sorry. I end here. Have a good

[@49ccscoot]

@@johnrobinson357 Crashing sucks. Getting old sucks. ...but bikes are awesome, so what can you do? Good luck.

[@c__TattinhNhi]

I see you porting very meticulously and accurately😊👍👍👍

[@Magoot2456]

Hey man, great video! Instead of using wd40 try using diesel for cutting lubrication for your burs! Works great! An old timer showed me that ivory soap works great on burs to keep them from clogging as well :)

[@MattySlimz]

Thankyou very much! After looking at my 1e40qmb case and Minerelli Zuma, it’s clear there is more meat on the case for porting on the 1e40qmb. The port maps thread on your forum I plan on using in the near future!

[@49ccscoot]

I haven't really checked out that area on the Zuma cases, but I know the clones have more meat left when you do a stroker crank.

[@darrellkelso9915]

Be real careful, most transfer ports are already too large and enlarging them more kills the velocity of the fuel charge.

[@frankie5341]

@@darrellkelso9915 interesting, that was my worry sort of lowered compression filling, we used to pack any holes in the crank with car cor plugs to raise the transfer vacum/ compression of gas up wards.

[@peggyparrow2059]

Here is just a thought, to gain back volume lost, is it possible to use cork and epoxy to hold, on the underside of the piston ? An old snowmobile engine trick.! Does not add much weight to the piston but maintains base pressure to force mixture into the transfers?

[@taters5586]

Hey man, great video! Iv just ordered myself a gasket kit and im going to split my bock and take the pathways out a touch and clean them up. Iv been messing with a 40cc poulan chainsaw. Did some clean up on both intake and exhaust ports, opened the muffler a bit and dialed the carb in. BIG gains. 18 inches of green poplar in 18 seconds. *video on my channel* Again thanks a million!

[@Syeda._iqraa]

just be sure u take out ur block not ur buba bock

[@smolu1]

Perfect. Nice to see You back for real :D

[@bumblebob5979]

This is a good channel! I'm really enjoying :) Keeps mood up too! Cheers! :D

[@faqih592]

Matornuon ilmune

[@JunkCCCP]

Thanks for the incredibly well explained video - your voice is pleasant to listen to and everything you explain and show is easy to understand even for beginners (or at least I think it should be). Do you have a dyno or access to one, or do you check your work for efficacy with the "butt dyno" only? How much power would you say you gained from all this porting and flow optimization, or was it more in service of making the cases able to handle the much larger pumping capacity of the 103cc bigbore/stroker kit?

[@49ccscoot]

Thank you! I wish I had a dyno, but I just do my testing on road. I do take numbers like measured acceleration times and top speeds and such, but I haven't built identical engines with and without the porting to know what comes from it and what comes from other things. It is just a part of the process of a build at this point.

[@danpedersen5816]

@@49ccscoot I know this is an old post, and I don't know if you have a Dyno now, if not check out simpledyno, I'm pretty sure you can make one of those, and it's free software, it's just the hardware you have to make, you have to spend money on.

[@julianjennings4638]

More physics! Air does not like going around corners. Use large radius turns. Short turns seporate the ful droplets and they go straight. Steps cause turbulance!!! ( fuel comes out of suspension) Again! Think in terms of the air wanting to go straight!! Keeping fuel atomized! Also remember, in an engine the air is pulsing in reverse too! Watch edges and steps. ( Knife edge) ramps must be gentle, to stop turbulance! Don't polish any inlet surfaces! A 60 grit cartridge roll finish is ideal. It provides a boundry layer ( holds higher air velocity) and lessens the fuel that comes out of suspension! Polish exhaust ports! Minimum 200 grit. Apart from matching cacing joints and steps, radiusing, etc. The more you remove, the slower the air will move. ~ " Flowing", while removing as little material as possible, will keep good midrange and improve top end power. Going Big will lose low end but gain power at high rpm. You spend about 60 ~ 80 % of the time at mid and upper mid rpm and throttle position. Think about it! Enjoy tinkering! Oh WEAR EYE PROTECTION! GLOVES! AND A MASK, ALUMINIUM IS TOXIC TO THE BODY. Google " silicosis"

[@kingcosworth2643]

Trenching can only help if the motor is at such a tune that a combination of the transfer momentum and the exhaust draw can draw intake air through the intake when the piston is at bdc

[@hocu420]

I port the heads of my 4 strokes if they need it as well, some castings are shit and have horrible ports so a bit of time and a rotary sorts that out! Some bikes you dont notice any change and others are like you've summoned and saddled Lucifer himself! But as of yet no dyno proof! Great all round video on porting, got a Peugeot 49cc I'm thinking of boring to take the 100cc cylinder and using the 125cc BB kit! Will have to check some of your other videos out!

[@EarthSurferUSA]

Reed valves don't like a lot of crank case volume. I know you can gain movement with the pipe effects, but with tight crank case volume with reed valves, the reeds tend to stay open longer as the larger volume of (elastic air) takes more time to develop a negative pressure to open the reeds. Wiith tighter crank case volume and reeds, the pipe should open the reeds earlier and keep them open longer.

[@kevinproctor8743]

I'm impressed. I imagine a bit of a lost art form. Goodonyou and thanks

[@ASOMOTOR]

what will happen to primary compression

[@49ccscoot]

It will lower. In some modern discussions they don't seem so concerned with primary compression and some prefer larger volume.

[@ASOMOTOR]

what is the effect of large or small primary compression

[@49ccscoot]

@@ASOMOTOR It can change cylinder filling, pumping losses, how peaky the powerband is or willing to rev and of course engine output. Most people comment about primary compression ratio and have never measured it to know if theirs is anywhere near any suggestions/guidelines because it's a pain to do.

[@Crazycarl66757]

ive never had luck with JB weld with gas.... it never lasts, how long has your filler lasted for?

[@49ccscoot]

The one in the video has been together for about 1.5 years now. I did get cracking on one side, but the aluminum and all cracked. This was aggressive porting and I crashed into a deer with the scoot, which I'm sure had to put some stress on every component. With or without the JB, I go through cases too much to have a 50,000 mile engine. Been doing JB in cases for the better part of 10 years now. I don't claim it's the best, but it has worked well enough for my needs.

[@julianjennings4638]

Do a piston mod and sleeve porting video too please. Love the port filling.

[@adegboda2079]

One and simple way to masure anything on engine at home is to count RPM's. Formula is simple. Any gaine in RPM's and how quickly it will hapen indicats that it works. Just switching to Iridium sparkplug is automatic 500RPM's gaine. My Vino 5BM with 68CC Malossi Alu. Cylinder made 12hp at 15K RPM's. I did dyno my scooter if you asking.

[@eric4946]

The inner corner is where you’ll see most gains , boundary layer thickness is very higher there. Want the curve to be as gradual as possible

[@mattmoilanen3813]

If I need to do fill work in cases I try to orient the case in a fashion that allows the filler to fill the low spot intended to built up if another coat is required I will just reorient the part if necessary and you get a smooth filled are with minimal filler to achieve the desired result.

[@extec101]

personally i think most of the time a good tuned engine for street use dont need trenching but just a blending of rough edges. to get the absolute last bit of power out of an engine it might need trenching but for most of the street tunes its overkill.

[@49ccscoot]

I agree that it's not a sensible way to mod a street engine. It's how all of mine are setup, but I've never claimed to be sensible.

[@extec101]

@@49ccscoot hehe who is sensible my engine derbi ebs is still going strong after 11 years of abuse in endurance racing street and lots of fun, still pounding out 17hp the same dyno numbers as new built. no block porting, 28mm pwk, malossi mhr replica 50mm, metrakit prorace exhaust/ hebo bufanda performance.

[@STIZEN9]

i wanna know what kind of dremel bit was used in the beginning, and how fast you were running it. it it cut perfectly

[@STIZEN9]

NEVERMIND

[@SiR2Dean]

Intakes need to have a rough not smooth surface, it helps suspend the fuel molecules. Smooth surfaces will allow the fuel to form puddles 😉

[@49ccscoot]

Right. That's well known with many applications. I can't say that it's so well known what is best with proven results for 2T engine cases which are not the typical inlet tract.

[@cricri7066]

Wet sanding the epoxy into the aluminium can increase the bond strength a lot.

[@adam_-adam]

Great video. Was just wondering if that black stuff works as good or better than blie locktight

[@49ccscoot]

It's permanent. Not meant for threads, but if you wanted something to never come out it may be an option. EDIT : Wait. The Permatex stuff that I put on threads? I was thinking of the JB Weld at first. The sealer just seals. It's not even a fully curing style so it's not holding threads.

[@billymanilli]

4:34 I think I have those same exact pockets! LoL

[@mitchellroebuck9635]

Have you tried not filing the crankcase port with JB Weld and going for volume not flow?

[@49ccscoot]

I have built engines with just port matching. The problem is that everything I've done for years has been significantly larger and/or higher revving than stock and I have ported them. I don't have anything to compare side by side.

[@upaiaq]

I would like to try on my kids CR 80 go kart engine,I appreciate your sharing your knowledge. Anyone have any advice on the CR 80 engine?

[@robertpierce1981]

Digging the graphics in this video. Note to self: I need to remove the chair from my hallway.

[@oliverscorsim]

Not bad check out two stroke stuffing he really can teach everyone some stuff. I agree and am glad you touched on the volume being the biggest increase. A spacer for the reeds would actually help what you did significantly. Currently the air flow isn't straight yet by your transitions. I personally have noticed puddleing with anything smoother than 80 grit and when I got certified for water borne paint we learned some data on surface finish to wetting and it seemed to agree I finish most areas with 50 grit. I am wondering why you dug your sweet filler job out and didn't just cut the cylinder? Seems there's a good 7-9mm that one could along with rounding all the edges on it. Seems like a bad spot for turbulence. Ever try shielding the crank? We did it years ago to a Zuma and picked up a good bit up top. Think much more after 13k and it didn't die off until 14500. Seems a yz cylinder could be fitted pretty easy from the looks of stuff but I never measured as I'm more of a 4 stroke guy.

[@49ccscoot]

I've never tried to shield the crank, but have seen/heard about it. TBH, wasn't really sure how to go about it in a dependable manner. Even though I do mod the cases a lot, everything of mine is street use. Most stuff today just goes over to aftermarket cases for flange mount cylinders to get more serious. A guy on my forum has done some conversions with MX cylinders on different cranks in the Minarelli, with adding plates to adapt the cylinders, but it has been a whole lot of work with varied success.

[@oliverscorsim]

@@49ccscoot I use Devcon in all my motors for various things give it a go think youl love the stuff and alumirod is also great. I did the rod to some thick can I cut up then devconed around it and built it up. Really easy and very worth it since you seem to die off around 13500. Love the work and check out two stroke stuffing dudes an animal. Think alot of his earlier work would transfer over for you.

[@49ccscoot]

@@oliverscorsim I tried Devcon on the first set of cases that I ever did long ago. I must have got the wrong kind, because it was very brittle and cracked quickly. I've been subscribed to Alex for years. He actually joined my forum some time ago, but unfortunately doesn't visit us anymore.

[@oliverscorsim]

@@49ccscoot I think your surface prep could be better I do 36grit after a heat soak in the oven at 350 for an hr and acetone bath and if I can get the time I etch it with some some muriatic acid after then a quick baking soda water bath. I use the aluminum devcon 10610. Haven't had a failure yet and that's how I close the decks on my Volvo and Honda motors too for lots of power. Hell even the turbo bike has parts of the cases reinforced with the stuff.. only way I found to keep stiffer main and counter shafts from just snapping the case around the bearings. Never go thinner than a 1/4inch anywhere it needs strength and shoot for 1/2in where you can.

[@colonialroofingofnorthcaro441]

Great video, had some hard to hear places when grinding but other then that, great vid and much appreciated

[@acurarl9929]

Permetex gasket maker never dries. How tgats worked well for you is a miracle. Fuel eats it/washes it away

[@49ccscoot]

Depends on the gasket maker. Ultra Grey and MotoSeal by Permatex are pretty commonly used. I use ThreeBond (HondaBond, YamaBond) on the case seal most of the time, but only resort to it for other areas if I have sealing problems because it is messier to work with and tougher to clean up.

[@paulmazzola398]

Doug Flannery calls it tunnel porting when match porting the case to cylinder. It makes a big difference in low end HP on snowmobile engine.

[@Sladep123]

Thanks for sharing all you have done and know. Have you or have you come across any data that would isolate the effect/gains of this wkrk by itself? Obviously the effect of enlarging the case area as part of the porting and trenching is hard to remove. Thx!

[@49ccscoot]

I have not. The career tuners and racers don't share much info that I'm aware of and they're the ones likely to have data for that sort of stuff.

[@jonnyb6570]

I just checked my 2001 Yamaha vino. It says 5BM on it too!

[@clay6637]

Two stroke Tuner,s Handbook and ask lots of Questions from people that have already been there .

[@williammoore8252]

I have a few professionally built full race 2fast 70s .....I notice many of your builts are on 50 cases .....is there a benefit to this as opposed to being built off of 90 cases....keep up the great videos

[@49ccscoot]

One benefit is that I can actually find 90cc long cases. That's the big one. If it's a smaller engine, then the 90s will have much larger crank area and cylinder areas than needed and I'm not sure how well ports would match up. I'm jealous. I wish I could afford 1 pro race 2fast 70cc. lol

[@williammoore8252]

@@49ccscoot I also struggle finding 50 cases as I also have a full race mhr 50....and a 2fast 100...all in full race mini quads

[@49ccscoot]

@@williammoore8252 All of the 2Ts are becoming more scarce lately. Sucks.

[@joescissorhands141]

Dude I WILL do a test of trenched V un-trenched!! I'm about to re-do (phase/part 2 build) the engine on one of my 92cc project saws, I was gonna just do it all at once (dropping cylinder about 8thousndths", refinishing squish band, and WAS gonna just do transfer work (am happy w/ the intake&exhaust ports from round 1) and crankcase-matching/flowing work, though now I'm tempted to do them separately and test (it's pretty easy for me to test, I use a large log and videotape so I can then go measure cut-times, when you're doing >20sec cuts the differences show easily, and your cut-to-cut variance is well under 2.5% in my testing so far and am just beginning to 'dial in' my testing/benchmarking station, have no choice as I'm about to make some BIG claims of >10% power from a muff mod I came up with ;D ) I can't help but wonder how a big-bore kit plays into this? People generally say nay to the 56mm (oem is 54mm) big-bore kits for this 92cc saw, and the reason most-cited is insufficient crankcase volume.....though at the same time, the crankcase//cylinder matching on this saw, OEM, is the most atrocious you've ever seen, quite literally just thin hard-edged gapping between the two for 'transfers', it is insane...I know that trenching/flowing that will *allow* far more in, but have to port the lowers &uppers to actually be able to move the new air....this is awesome I have a good walbro on this unit it should be capable of a good deal more power, these guys like to cut at around 9k but am hoping to make it like 10k rpm more *AND* have higher compression ratio at same time ;D

[@49ccscoot]

Not sure how the saws are setup, but for scoots the transfers can be more ideal with smaller bores. Our transfers are way small compared to similarly sized MX bikes, and they also go much more straight up where better designed cylinders have teacup handle transfers that curve around into the cylinder entry instead of taking a sharp turn like the straight transfers. For us, case volume can be pretty easily changed with spacers under the reed block.

[@HuxTheSergal]

What about removing rotational weight? Lighter magneto wheel, light piston etc, does it make any sense/ actually does something?

[@49ccscoot]

It can help the engine respond more quickly. I've used the NCY/HOCA style small flywheels that are lighter and move the mass nearer to center and it woke up a higher revving build. I'm sure it's only better still with the inner rotor ignitions. With the racing stuff, it becomes a bit of a necessity... at least with the Minarelli engines. We had a guy on the forum that tried to use a stock flywheel with a Polini Big Evo 94cc and the flywheel came apart. Another easy way to ditch some weight on the Minarelli is to get rid of the starter clutch. Those can be pretty hefty and they're attached to the crank. Obviously don't do that if you're attached to electric starting though.

[@HuxTheSergal]

Thanks for the reply, I'll look into lighter pistons first, since I'm going to put a bigger bore kit first, the other scooter might get a lighter flywheel first, it won't be exactly apples to apples comparison, but we'll see if there's going to be a measurable difference in how they run

[@bradleyyounger8499]

Considering doing some minor porting on my am6. Now I just need to decide if I want to attempt it myself or find someone with experience pay to do it for me as no not end up with a pile of scrap aluminum lol

[@49ccscoot]

IMO It depends what you want from the experience. A good pro porter can get results that you and I won't get, but if you want to learn the whole process then you have to get your hands dirty. Plus, some of us enjoy the process. If you've never port matched cases, then maybe start there and see how it goes.

[@guidosamson682]

Have u done a dyno test with and without trenching

[@49ccscoot]

No.

[@dedeabsrn8044]

Automatic choke does not activate in cold engine. What is the reason? How do I set it.?

[@49ccscoot]

Most enrichers on small scoots expand when heated. When they haven't had power for a while and they're cool, they should allow enrichment. They sort of default to enrichment. You may want to see if the enricher is stuck or if it expands and contracts and check power to it. kzbin.info/www/bejne/hWPUg4mFoMuXl7s

[@kingcosworth2643]

When you are marking your gasket you are much better off staining the flange well past the gasket edge and then use a scribe to mark it. This is far more accurate when you are grinding up to it and is far easier to tell if you are going to go to far.

[@equittone1839]

Im sorry for my bad english, what happen if i only porting the cylinder and not matching with the engine case? Thanks🙏

[@49ccscoot]

There wouldn't be much point of porting the base of the cylinder any larger than where it meets the case. If you are altering ports where they enter the bore, then it's possible to improve performance without modifying the base.

[@freeenergy4everyone]

Maybe you should have shown the checking the base gasket against the cylinder first and then matching the gasket to the cases as there are bound to be gaskets out there that don't match the cylinder perfectly

[@BrattyBiker]

Just curious, with that port trenching work, you are essentially trying to skip primary compression by making the incoming mixture to go into the cylinder directly, Wouldn't this starve the bottom-end bearings from lubrication ?

[@49ccscoot]

As I've done it, it should never be effective enough to starve the bearings. Plus, if any oil or fuel/oil mixture falls out of suspension, it should make it's way to the bearings as it always did. I've seen some that shield the crankcase with a metal barrier, leaving only a slit for the rod. I'm not sure if or how they deal with oiling in those cases.

[@BrattyBiker]

@@49ccscoot Cool! Thank you!!

[@parkerwinegar7199]

The Jb weld that your using isn't fuel or oil resistant I'd look into the jb weld that is

[@frankcrawford416]

I am sure it might be oil resistant, and maybe gas, but it is not ethanol resistant, as alcohol breaks it down.

[@peter0139]

Did the JB weld hold up? with heat, gas, vibrations etc?

[@49ccscoot]

Yup. Current engine has the same treatment and it's been in the scoot for 2+ years. Even blew a crank bearing and took out a crank and variator ramp plate and it's still fine.

[@martinkralicek4856]

just now trying to port a 700cc 2 stroke from your video :D

[@49ccscoot]

Wow. What is it?

[@martinkralicek4856]

@@49ccscoot zabel zm29

[@jimvincenti2324]

Good video but with a lot of material removable at the base of the cylinder I wonder what kind of reliability the engine will exhibit especially with the continued enhanced vibration.

[@49ccscoot]

I can't say I've had many issues... aside from my recent 103cc LC engine (these actual cases). That thing refuses to seal on the top side (cyl to head) long term. Could be a combination of many things, including this. Other engines have been fine. My 86cc is done in a similar fashion, only just slightly less aggressive, and it has not leaked at all so far. That's a better designed kit though and I tend to think it stems more from design of the cyl and head, but the more anything can flex, I'm sure it can become problematic. This is somewhat the conundrum in many applications regarding performance. How much is too much and what sacrifices or compromises are actually worth it? In this case, it prob is the smarter bet to be less aggressive. I definitely wouldn't do this if my #1 goal was a daily rider.

[@damnthiccassboye7138]

Can you tell me if doing that will improve engine performance ??

[@49ccscoot]

I think it does, but I don't have any back to back data to show it.

[@AutodidactEngineer]

Is it advisable to use red rtv gasket maker instead of the stock gasket because my chainsaw is no longer made and it's impossible to find replacement parts!?

[@49ccscoot]

Most likely you can find a gasket material that is close in thickness. That may help to retain the original properties of the engine (due to spacing). Permatex Ultra Grey or Motoseal or ThreeBond/HondaBond/YamaBond are more common gasket makers for 2Ts.

[@AutodidactEngineer]

@@49ccscoot I will consider them, thanks!

[@Jazeeti]

What effect does the filler have? Will the mixture attachs it self to it? I think you have removed to much. Specially on the cilinder skirts. Good video tho

[@49ccscoot]

Some of the filler is necessary because extreme porting cuts all the way through the cases or leaves them paper thin. The filler on that ledge below the transfers is to get rid of an abrupt corner and create a transition up toward the transfers.

[@Jazeeti]

@@49ccscoot I understand but the filler material doesn't help with the flow. Because like cold aluminium the mixture codensates against colder materials. This is what can happen with the material of the filler?

[@49ccscoot]

@@Jazeeti It's possible, but there's not much choice and I've seen some people way smarter than me using similar fillers to reduce volume or direct flow.

[@marvinschweizer6636]

I have a question will this not change the crank case pressure

[@49ccscoot]

Changes in crankcase volume will change the primary compression ratio. Increasing volume lowers primary compression.

[@jamesmclean7757]

Can these techniques be applied to 1/5 scale RC car engines of 45cc?

[@49ccscoot]

I'm not really familiar with RC engines, but if it's case reed induction then the general idea should be similar.

[@davespooney8472]

Wouldn’t port work potentially direct less oil to the crank bearings?

[@49ccscoot]

It could, but work like mine have won't isolate the crank enough to be an issue.

[@horstpopescu1170]

Ich nehme mal an den Kunststoff den ihr verarbeitet das ist ein Epoxidharz wahrscheinlich Aluminium gefühlt und ich persönlich wäre da sehr vorsichtig solch einen Kunststoff in einem Motor zu verarbeiten und ich bin nicht davon überzeugt dass das auf Dauerbestand hat. Grüße aus Deutschland

[@49ccscoot]

I've used it for years. I have had it crack before. I haven't had it fail and cause any major problems aside from case leaks.

[@Gogetter0118]

Do you trench out the boost port stright down?

[@49ccscoot]

Yeah. Not really trenching that. Just port matching. For the Minarelli, I go straight in and radius the end.