2 Stroke Tips & Tricks [Blowdown]

[@theironhorse6600]

A perfect video explaining cause and effect of changing blowdown, deck height,and exhaust pressures! I agree 100 %! Spot on information!

[@DaveyBlue32]

Good to see you jumping in to give old Charlie and big thumbs up 👍… keep on Truckin ya old horse!!! 😂😂😂👍🇺🇸

[@justinweaver8107]

Hope u are well sir have a good weekend.

[@bkh5746]

I seen a trick on my kart cylinder.guy pressed liner out and shimmed the liner to raise the ports

[@Doc-Cole_Trickle-of-Chainsaws]

👍🆙Harvey

[@IndianaDoug]

Great explanation of reversion and blowdown, I always learn something here👍🏻

[@ErikLong-s3g]

Charlie, this video is one of the better videos out there. This helps people like me a tremendous amount. I am very grateful for people like you and Ironhorse and Tinman and others. Thank you

[@DaveyBlue32]

This is a great explanation video of how your saw works… every starting saw builder should watch this video! A+ buddy!!!

[@wadekauffman3503]

For what it's worth, I've ported 3 saws mostly because of the information you've put out. I watch others as well, but I connect with your videos the most. I'm VERY happy with the second Husky 359 I ported. I bought it dead and put a Hyway top end on it. You're right, I gives a great sense of accomplishment. Thank you for continuing to help us newbs out.

[@bradpotter6401]

Thanks, this is just the video I was looking for to explain what "blowdown" is! Also for giving me port timing numbers and strategies for doing modifications. Your cut-away engine made everything you said perfectly clear.

[@tinolino58]

As a professionell 2-stroke tuner I observe similar effects. Blowdown bellow 21 is good for mopeds in need for a wide powerband. But when it comes to higher power I use 23-26 degrees of blowdown. Mopeds have an inherited advantage: the longer exhaust system where we adjust the frequency and intensity of the return pulse in order to minimize reversion. Your adjustable exhaust system mimics this effect on a very small space! Great tuning 😍

[@carllangley1764]

Thanks for the great information!! I've done small porting on dirt bikes and snowmobiles all my life ( nothing drastic) and today you have taught me some great information about the timing!!

[@rchighfield1]

Man I sure appreciate you sharing your experience and knowledge to help us. Great job with the blabber factory, you did great explaining.

[@DaveyBlue32]

Love your variable tuning pipe idea to let you test and find your saw’s preferred exhaust configuration… sweet idea!

[@Teciprac]

Very well explained. I admire your integrity in sharing this. Thank you!

[@ragercrepair9301]

The adjustable exhaust system is a freaking awesome idea! That's just a damn good idea. I love that! Get all the scavenging tuned perfect before a muffler/pipe build. Would also give you a starting point to build pipes in bulk of you port the same on several "work" saws. Like the 4910 or 7310 work saws. Great video! Love the educational content!

[@johnw5242]

It seems to me it may also be a great "actual in the bush" exhaust if it can be kept not only strong, but compact as well. If your banging the exhaust when your into the dogs, that's not real good when you have two very SMALL screws holding that to the front of a very hot aluminum cylinder housing, so yes - compact is of great importance if it's going to be of use on a work saw. Everything effects everything. Pipes are best built for a motor, not the other way around. So - if you change your ignition timing - build a NEW pipe? Not practical. What if you change your air filter and open up the intake? Exhaust tuning can and sometimes definitely WILL under those circumstances. "Another new pipe design?" How about: 1 - Loosen (thin) Locknut 2 - Turn adjuster clockwise to reduce internal volume, counter-clockwise to increase internal volume. (Season to taste) 3 - Snug up (thin) locknut 4 - Have a nice day

[@FYMM69]

Of all the timing videos I’ve watched, you my friend have the best explanation yet, by far. Thank you

[@matthewknight5641]

Man its awesome you and a few others are giving us this education. Ive learned alot from you and really appreciate what you do. Your trial and error and sharing your journey is helping this whole community. Thanks man for sure

[@dominikweber4005]

That was one of the most informative and useful videos of understanding and learning how 2 strokes work and how everything influences the efficiency and output and what to do and not to do. Thankyou very much. Ive stated off with chainsaws and weed eaters and snowmobiles, and now I have a 80cc 2 stroke kit on a bicycle. Absolutely love 2 strokes. Appreciate it

[@slaxxx]

I plan on porting someday! I’m at the phase where I’m just diagnosing and fixing saws. But I’ll work my way up. Thanks Charles!!!!

[@johnw5242]

You're well on your way! Tear-down, clean-up and DIAGNOSTIC are the BUILDING BLOCKS! Re: Mods - if you have a "Honestly - built as a fire-wood saw" that you want to start waking up, start by buying yourself a $15 degree wheel, a large pack of JB Weld, and a dremel with some good burrs and maybe some stones. (Ask one of the guys doing it every day what works best for cutting the aluminum / JB Weld - and what's best for cylinder work. It will likely be two entirely different burrs) If you have, like I said, a "Built for firewood only" saw - you WILL find plenty to do in the bottom end flowing from the crank-case into the lower transfers. It is THE most recommended "1st time" "2-stroke" "porting" "project." You don't even TOUCH the upper trasfers, so you won't do anything that will hang a ring up or chip the plating in a "High(er) fatigue area." It won't make your 1.2HP saw into a 9 HP skip-chain beast - and it WON'T even do as much as a base gasket delete and muffler "Flow Improvement," but it's port work, and it WILL improve the saw's power. It will also make every later improvement you make BETTER. I hope you can find time for it before too long, but either way, thanks for all your hard work keeping the folks in your community WELL OUTFITTED!

[@andrewotero1972]

School of hard knocks ain't cheap been going to that school for a long time working on my masters lol Been porting saws for many years You do a pretty decent job of explaining your theory! I've always tried to explain the balance to customers when porting you got to build the saw to the customers needs and cutting style as well as application and conditions Thanks for putting your time out there

[@johnpower8356]

This makes me realize hiw important 2 stroke exhaust is. I used to think these scooter guys that spend more thsn a couple hundred $ their pipes were crazy, but it is super important. That 2 cone expansion chamber works

[@jacobhein4319]

So i heard johns custom saws say that you want your intake to open after youe exhaust closes. I couldnt figure out why until now! What a great video!!!

[@marcuscicero9587]

got a good idea about what reversion and blowdown is. thanks

[@Specledorf]

I'm new to learning about exhaust systems and I'm glad I came across your video sir!

[@matthewknight5641]

Man its awesome you share your journey and teach us that are trying to learn

[@trailshready1674]

This was a very informative video. Damn fine job explaining everything 👏🏻

[@BuckYaSaws]

See you learn something new everyday. I 100% agree with the suck back, some how I’ve over look that little detail all the years I’ve been around small engines. I took small engines in tech school and worked at a small engine shop for 8 years. Great video explaining two stroke porting & theory!

[@pastormike5054]

Best explanation it removed some mystery for me thanks

[@kenturmon9428]

Keep in mind exhaust port area will affect blowdown.the numbers don't tell the whole story. The faster you can evacuate the exhaust gas the sooner the transfers can open. exhaust width is very important.

[@CharlesBrisco]

Yep so is how free it can flow out of the ex too port shapes play a factor too

[@steppoffaith8426]

It sure does. The port area is really important for that and other reasons.

[@srankin8022]

Great video! I agree with your tendency towards more blow down especially when talking about work saws.

[@justinweaver8107]

Great information thank u sir

[@pastormike5054]

Just watched this again I'm learning

[@AndyAlaska375]

Thanks Charles. 👍

[@ragercrepair9301]

I just ordered a degree wheel and I'm going to try some of the tips and tricks I've learned from you and a few others that you know and are friends with, to start the build on my first full port job! Wish me luck man, I'm gonna need it. Lol

[@robocarston7029]

Adjustable exhaust.... I'm glad I thought of that. LOL😅😊

[@edwinburns4785]

New here and this is a great video, thank you. Been playing with a Husky 51 and Styhl 028. Porting if you want to call it that. I was having a hard time with the blowdown concept and now I think I have it. I like that you give your numbers which gives me a basis to work towards.Back to the shop in the morning and the timing wheel. Thanks again.

[@ronkolb1335]

Love to sit down with you, Flagg, Walker, Dyno-Joe, Ripsaw, and others to hear your ideas about your builds and why.

[@oldcodger1929]

I think you do an excellent job of explaining things. I'm pretty dense and get what you're saying. Thanks.

[@ceskajee]

What sounds variable exhaust lenght sounds? Maybe vacuum usable horizontal valve? Which open/closes with Rpm. Even better if it could use ECU to work. Exhaust port could use like Yamaha YPVS system👍

[@70sport37]

Thanks for the info my saws are running good enough without burning up the bar but my old Tm 250 Suzuki might benefit from this info .

[@scottashton6533]

Great video that made awesome sense and I would love to try something like this on my Kawasaki 2 stroke

[@WestVirginiaEricDSmall]

And purchase what I thought was 50 CC's however the Pistons 47 mm across by 47 m down and then like connecting rod is stamped FM80 CAN YOU TELL ME WHAT I HAVE HERE IN CCs?

[@GlynnRussell-ew3pp]

Love your explanation of blow down 👍

[@jimmykulik3438]

I have never seen carbon deposits in transfer ports, usually l was told raising them make more hp and a higher power band?

[@toddzilla6491]

Great video ! You just showed me how to go back to a motor I ported. But ruined it. And reevaluate my numbers. I think now it’s problem is blowdown. Thanks for the information I really appreciate your vid’s

[@dalewhitmore143]

What causes light carbon build up after the piston ring? worn piston rings, cylinder or both? Can you still hone a small open port saw like husky 120e? Are they still able to be ported?

[@robertdixon4554]

A combo of compression and more blowdown ? Correct?

[@chrismuncey3861]

That makes sense I just built a Ironhorse style pipe like that 1.5 main pipe 4" long with 7/8 exit. It pulls but at lower rpm and couldn't figure out why now I'm going to shortin it after seeing this!

[@obbyjep7597]

Really like that adjustable lenght pipe idea, should allow getting it just right. Might be more hassle that it's worth but you could adjust it for different kinda of cutting, ie bucking vs limbing

[@TimberTramp]

What about a washer like you were talking but using a spring behind it I wonder if it’d tune itself…theoretically “optimum” throughout the rpm band…be fun to try

[@thelongranger55]

I cant lower the cylinder for my ms290 cylinder because the crank case seal seats are built 50% into the cylinder 50% in crank case . could definitely do it with bigger cylinder with flat base like like ms440 for example. But yes great way to gain blowdown as you mentioned. If you do deck the base of the cylinder & the piston makes contact with cylinder at TDC You could probably take some material off the top of a flat head piston keeping it flat & or ramp it to gain more blow down if you can’t port any further or want to keep port numbers

[@matthewknight5641]

I wish you would do more tips and tricks videos

[@CharlesBrisco]

There's s play list with a hole lot of tips an tricks

[@marksarkaquariums9056]

Great video,its easier to show how the engine works with a cutaway block.It made me think about how not running the second ring would allow the transfers to communicate with the exhaust on the up stroke, causing it to suck exhaust through the ring groove.

[@johnw5242]

If it's a race-only saw, it's something many like to play with, but a piston that's designed to have two rings has trouble running true if you run the top ring only I believe. I'm no pro, but I believe you will see a TON of wear in your skirt(s). The position of the wrist pin can't be changed to compensate for the lower ring that's no longer there. In the "world of two stroke," there ARE - *some* applications where you can find a "Race Piston" that is designed to run a single ring in a cylinder that runs a double ring piston stock. I believe in most if not ALL applications, the position of the wrist pin in relation to the surface of the top of the piston, as well as the single ring's thickness and position in relation to the piston's surface are all quite different than what you'll find in the original "Two ring" counterpart. This is NOT to say that some don't sort how to successfully eliminate the second ring. It can be done in some cases - just for "competitive purposes," - but reliability is not part of that program. :) The other thing you can do is BEVEL the rings so they are thinner where they contact the cylinder wall. This can be done to reduce parasitic losses - but again - this is a race mod, not a "working saw improvement."

[@johnw5242]

Charels, you have a great approach. Air is elastic. Great idea for the variable tune pipe. Truth is, because there is variance on every saw - an adjustable pipe would be a great design, and something that could become a decent product. A broach to clean up the weld on welded pipe for a cleaner, truer bore - and have a range of available sizes based saw displacement. So, one (field tuneable) pipe would be 60-70cc (with a disclaimer of course) another for 80-100, and one for 110-125 102° is also nice number because even if you overshoot just a degree or two, you've still got a rock solid work saw rather than a "coulda-been a LOT better. It's easy take more later if it's really not awesome at a more conservative roof height. People who want to bicker with you bicker with everyone, so, you're no more "special" than anyone else "actually doing something." The "bickering people" bicker with everyone equally - overall. If 1/3 of the people you interact with thing your full of - constipated - or are angry with you over some pretty minor this and that - you're probably doing exactly what you aight to be. :) 1/3

[@theironhorse6600]

Well said John!

[@acurarl9929]

What about doing nothing but raising exhaust port to gain blow down. ??

[@matthewknight5641]

Do you think the pipe length and power experienced would be also adjusted by timing advance or reterd?

[@johnfairweather3178]

Great info many thanks

[@jimsworthow531]

awesome description on 2 stroke theory.

[@findvoltage]

thanks Charles. appriciate you wisdom. saving us all time and money.

[@billhamby6230]

250 polaris boss i just got new piston rings both rings marked same wich is top ring

[@hillbilly4christ638]

The design of that exhaust port reminds me of a fueling valve. That valve will actually improve exhaust extraction and prevent backfire, so your theory is based on existing technology. It would be interesting to have a straight exhaust port with a cone in the exhaust pipe. You could flip the cone either way and see what effect that would have on performance. Also you could move the cone in or out and test performance that way. The only problem I see is the tuning would be saw specific and not universal. I don’t see any heat problems with this setup as the gasses are more free flowing. I believe heat issues come from high compression application, but higher gas concentrations would tend to cool that as well. Just think where we would be with two cycle without the stinking epa.

[@snort455]

will reversion cause fuel-air ti stand off from the carburator throat? im thinking the saw had a plugged exhaust. peobably a sparh arrestor

[@MrDriftaX]

Everything you said makes sence too me. Cheers mate

[@Doc-Cole_Trickle-of-Chainsaws]

👍🆙CB, Has your thoughts changed any since making this video?

[@joebrown967]

I had a ring snag in my upper intake port can I port it a millimeter or two away from the upper intake port as like a bevel kind of deal so I can save my cylinder hopefully and if I do that, what other changes do I have to make if you don’t mind me asking. I’m trying to follow this video the exhaust makes sense. I just didn’t hear much about the intake.

[@WreckitRalphie]

I want to get my 590 timberwolf ported. Or do it myself. Your videos are awesome

[@olefugle]

Thank you. This was very clarifying to me.

[@Ecksterphono]

Many a books have been written on porting theories and the advanced social media tips and tricks on how to get the most power out of a two stroke there is no end. Imagine if you will if one can advance the technology by using sensitive thermocouples to variably time the ports at any given load, temperature and demand of a saw when needed and the ultimate power under every given condition would be amazing and an undertaking that would take quite a while to achieve the best volumetric efficiency that a saw would have would be awesome.

[@Newso-m2b]

Just wondering have you had any success with changing crankcase compression

[@joshuadulaney5559]

Nice video, good work man!

[@guymansford7123]

Thanks, that's really clear and helpful.

[@unclestu5960]

Awesome explanation bud

[@novicelumberjack]

Awesome video Charlie!

[@Doc-Cole_Trickle-of-Chainsaws]

👍🆙BigGuy

[@Duanepa.2]

Thanks! Great explanation.

[@donnywalker4691]

good video bud

[@CharlesBrisco]

Thanks

[@chriseller757]

The problem is that 98% of us don't have lathes or mills to cut the squish band.

[@EngineKrahnicles]

Dang. Im not a 2 stoke guy, but this just blows my mind. Its all about what you know

[@williamlongfellowjr.1]

So how do you obtain the blow down,do you file the port down ,while watching your video and heard you get more gas into the fire chamber which you said to much is bad then why port

[@asphaltcowboy7868]

Since you are mentioning blowdown a lot with the two stroke..im wondering if I was to swap out my stock dome piston to a flat-top piston, would this make any difference???

[@kingboymachine7329]

it will reduce compression ratio

[@asphaltcowboy7868]

@@kingboymachine7329 why would anyone want to reduce compression? I'm confused 😕

[@michaelwheadon1078]

Two thumbs up!

[@jadeolin8514]

Those pipes are designed pretty much identical to the nitro r/c racing pipes I used to run in the late 90's.

[@davidcarpenter8741]

The black art of chainsaw porting! Thanks for the lesson, great video

[@Machinenfabrik]

Great stuff. You da man. Thanks for sharing.

[@williamlongfellowjr.1]

How can you get more blow down

[@CharlesBrisco]

By machine work an raisin up the ex port

[@jammerrcful]

Frequency resonance....a beautiful thing.tunning is a science and an Art in a way. To get that crisp rpm followed by hp when cutting deep is satisfying. I run 102 octane Vp with 927 castor. The performance and smell❤..lol. film strength with a 70:1 mix ratio freed up some ponies alone.

[@WreckitRalphie]

How are u getting transfers done with the harbor freight rotary tool??

[@CharlesBrisco]

with bits an sometimes a China 90 that fits the hf cable

[@WreckitRalphie]

I'd like to get that China 90 lol

[@joebrown967]

When you say you increase blow down, does that mean you are raising the exhaust port?

[@CharlesBrisco]

U can change bd by raising the roof

[@Szczyrczek]

Thank You!

[@nathanmcdonald1585]

Thanks man for you video

[@pablocampos4551]

saludos desde venezuela... buen video..

[@abeldoang8146]

Thanks bro

[@GlynnRussell-ew3pp]

Great video like your views !

[@NothingButChainsaws]

Did you ever build that custom pipe for the echos?

[@CharlesBrisco]

I've built a fue pipes

[@NothingButChainsaws]

@@CharlesBrisco the adjustable pipe, like you where talking about in this video.

[@CharlesBrisco]

@@NothingButChainsaws I had one i Made that slid in an out but I did not like it

[@rtdc5662]

More compression, more intake, more exhaust, more fuel, it only makes sense to have more blowdown...

[@DaveyBlue32]

I’m all about leaving all my exhaust duration and I leave them long for as much torque as I can get… I don’t expand my exhaust port window’s as I think most are too big to start with… My thinking is very close to yours partner… there’s lot’s of videos of saw’s reving and cutting a couple cookies but I’m all about keeping my saw’s extra rich and not allowing them to free rev into the upper stratosphere… I don’t need to spin up that high…I’m cutting at 11k or something less than 12k so I’m good right there… I love my little bearings and my crank and I want to hug them and squeeze them and give them lots of oil in my mixture and not spin them too fast! 😂😂👍😂💪🤪🇺🇸💪😎. I like the longer bar and less bending over… my short legs like a 28-32 inch bar… a 36 or 42 I have to lift it and swing it so I’m not dragging it’s tip on the ground… that’s more work… I’m lazy and I always look for the ways to get it done easier and faster and the cheaper the better!!! LMFFAO!!! When I was younger I was a rammer and a hammer and gammer… if it doesn’t fit get a bigger hammer type dude… in my older age I’m more into the “just enough to get it done, kinda thinker.” 😂😂😂. You can cut a lot of tree’s and wood with a good built 50cc size saw… and not be exhausted at the end of the day… 😉👍

[@steppoffaith8426]

Amen sr!!!!

[@jeffreyhagelin3672]

When you mention J-B weld I was tired of the conversation

[@tomperkins6522]

I’m working on a Jonsered 510 or 520 and I can see the piston ring through the intake at BDC! I have future plans of lowering the squish about 70 once I get a lathe which will solve it. I’m just curious how it will affect performance until then

[@Ecksterphono]

Darn EPA. Its all about emissions. Its all about balance when it comes to porting.

[@wompwomp9]

If you could see yourself the way I see you, You woulden't be so critical of yourself. You Rule at what you do in my eyes. 👍

[@RichFife]

I too like more blowdown

[@CharlesBrisco]

I like like more bd to

[@tonymayhew191]

I am a firm believer in getting the spent charge out and away from the saw as quick as possible! These EPA idiots have tried to use the exaust pipe as a way to catch the hydrocarbons and spark arrestor, and Baffles, That's way too much crap for the heated burnt gases to be trying to make its way through to exit the engine! I believe it is the root cause of all the newer stuff over heating and cooking a piston! All I know is everytime i pull the muffler and drill a hole in between the two bolts that hold it on the cylinder it's a night and day difference! And if I have to cut on federal land I put a spark arrestor back in the pipe so I don't have any issues with the law or worrying about catching the woods on fire! Last time I checked your equipment won't be spitting sparks anyhow if you operate and maintenance them properly.

[@larrytemen4789]

Your videos need to come with a warning. Now my saw makes more HP than my Toyota Camry lol

[@crazyfeller5704]

👍