Porting your 2-Stroke motorized bicycle engine

Porting your 2-Stroke engine can help facilitate a smoother running engine. This tutorial will show you how to successfully carry out some porting procedures to increase the reliability of your 49/66/80cc motorized bicycle engine and/or 2 stroke engine. Please refer to our tutorial at juicemotoparts.com/portwork for more information about this process as well as where to purchase the tools required for this process. The reading from Gordon Jennings's 2 Stroke Tuner's Manual is also available there. Feel free to comment or shoot us a message if you have any questions or need any trouble-shooting advice. Thanks for watching and as always. GET JUICED!

[@BeezyKing99]

for all those who are curious about the link, forget it, it's a broken link which brings you to a page that isn't even related to this guy's channel.

[@JuiceMotoParts]

Thanks a lot Daniel! Means a lot to US and we are always glad to help out with any problems you may have! Good luck!

[@frankcrawford416]

What a fine tutorial on 2-stroke porting.

[@YorHighness]

Remember these are crude chinese engines and his port work od excellent. This isnt rocket science. Stop hating.

[@BaileyEvans]

I would like to see some examples of these mods running.

[@antoniogonzalez5826]

I'm learning too. Thank you!! Good video.

[@gkcoupe]

hi i just wanted to thank you for all your helpful advice.. this video helped me gain 10 mph.... i did exactly what you suggested with the exception of deburing the transfer ports.... i only had a file at my disposal....

[@hakkedbitchhh7686]

Great video, excellent attention to detail.

[@djstl100]

While im not a two stroke expert, im trying to learn some stuff about motorized bicycles before i build one.....and all i see in the comment section is... "your doing it wrong"... so i went to there sights to look for there 2 stroke engine work and all i saw was videos of other people doing stuff ,how to get through video game levels & shit....trolls...good work.

[@JuiceMotoParts]

I believe i saw one of those before on KZbin. some guys made a prototype with two carburetors wired to one throttle. It was pretty cool.

[@jsollien127]

Good info. And all in one take!

[@Visiorary]

Holy [Bleep]! Get Juiced! I final wash jugs (especially 2 stroke) with scalding soapy water. It dries fast. Pistons too! Two Stroke is Heaven!

[@Sonoknow]

Nice job

[@xxkillersnakexx]

I find that porting and polishing does increase overall performance based of of my own personal experience and the videos I’ve seen on KZbin. Another benefit to these motors would be to ensure that the cylinders have been honed for a more advanced oil saturation on the metal surface to increase overall lubrication since you’re increasing the surface area by using a honing device.

[@stevesolo16]

The best tools to port with are from FOREDOM. There is a company called C & C enterprises who sell all the porting tools you'll ever need. Start w/ a 90 and a straight. I have been porting all my adult life. I have set 14 Land Speed Records on small bore 2 stroke engines I have built. I 've done karts, GP Road Race motorcycles and am currently doing drag race V8 engines. It's a good idea to study the mechanics and theory on how the gasses flow through the engine. You need to get a real grasp as to what happens in each port as the crank turns.Do the gasses flow front to back or back to front? How to build a pipe that is going to help you achieve the powerband and over rev...porting to that pipe. What about the head and squish velocity? A good pipe and good head work...along with jetting the carb correctly will net you more power than a port job. The porting is just icing on the cake. I hope this helps. In college, I studied flow dynamics. I fell in love with physics from 2 stroke motor building. Good luck! And chamfer those ports!

[@MattDemery]

got a video that better explains how to do this?

[@chrischarters376]

Steve Solo excellent constructive comment. I agree 2strokers can be extremely inspiring!

[@theespinozagrove]

What’s the best way to get more power out of my 150cc gy6 Engine thank you

[@JParkes43]

Good work

[@sammyrussell936]

Awesome Info..Thanx Bro

[@sesquipedalianstan]

Your knowledge is so extensive it is RIDICULOUS.

[@turbotonic27]

very informative video ! great thanks

[@freepatriot6313]

+turbotonic27 actually....no very destructive and totally wrong information. If you follow this ...you will be replacing those cylinders and pistons...and probably crankshafts as well

[@AlvinSmith]

great job.

[@johnbasten4077]

Spot on Christopher

[@lilman1796]

Thanks for the video, great info. Keep up the great work everyone ☆☆☆☆☆☆☆☆☆☆☆☆

[@9014jayvictor]

lower the in take raise the exhaust ramp the transfers and chamfer to avoid ring breakage buy the window piston and the reed cage

[@sailingvesseldrifter1759]

Come on guys. Cut him some slack. I get the strong reactions but who was perfect the first few times? I fully understand its best to be precise and have proper tools. However give credit where credit is due! Hes at least trying. The difference between my first build and my 3rd and current build is unbelieveable. Some of us are self taught. Take it with a grain of salt. Or leave it. Better question why did you finish the vid then waste more time leaving mean comments? I may be female and self taught but i bet my bike is faster than yours!! ;)

[@chrisnapierutube]

Yes that's all well and good, try away on your own project , but maybe only advise others on things you are really expert on? Balance is very important and a lack of it will put undue stress on components including the bearings, ( I imagine there are some ?) I've not bought one of these engines yet. BTW your bike looks amazing.

[@nateandyourmom]

I just went to the comments first.But i see.Guess im on my 3rd build.First engine works,i just took it apart to tinker with it .Im new to this but want to learn.Couldnt i just take that engine,watch some porting videos then just port that s.o.b?Have that 3rd engine on the way.Or should i try porting the new one coming?Or should i just go back to kicking fucking ass!Mr.60

[@rickreese5371]

Great vid G

[@billtucker9455]

Thank you

[@windshieldrepair5961]

Thats a nice trick.....with beveling the pistion and cutting out portion to increase fuel delivery.....Id like to make the changes when I put my new piston in after some use.....

[@williamhart1125]

Great tips, I LIKE IT

[@jickdawmonelason7239]

Well you're a moron...

[@amymck6410]

Great video, but " Taking meat off the top of the piston" Squish is mega important and so is a crisp edge on that piston to control port timing.

[@MaksGarmata]

it's the best vid about the porting that i ever seen

[@roudyroy1]

if you were a blind man....

[@MaksGarmata]

roudyroy1 you can do better?

[@OGMR2COOL]

HEY THANKS 1 MILLION FOR THE INFORMATION MAN I'M ABOUT TO MAKE MY MOTOR BIKE STUPID FAST!!!!

[@GadgetAddict]

Very interesting. I can't imagine that I'd need more power out of my 66cc but it's still good to know.

[@aviverde9031]

@@santanazachariah2470 wOw ThAnkS gUyS wHeRe i hAvE tO pUt mY cArd NumBer dOwn ?!? :(L):(:):))):): pricks.

[@jameskendrick41]

If u want to port make sure to also stuff and flow your case. Also index the spark plug.

[@JonathanShawTheCulturedBrummie]

subscribed. first video thats actually taught me how to port and polish the two stroke. ive got a 1990 Yamaha RX-S 100 that i want to chop down and modify into a dual purpose scrambler/cafe racer. do you know anything about modifying forks,swing arm. upgrading shocks and raising seat height?

[@andymandyandsheba4571]

chamfering the ports and the skirt of the piston on the induction side will also will rising the compression by having the head skimmed also might be worth finding out if you can get a reed valve set a tuned exhaust would help a lot

[@gkcoupe]

just wanted to say thank you for postion this video the bike gained power all around and now revs more like a chainsaw than a bogged down P.O.S ......lol...... i look forward to any new videos you might post..... especially one of a running bike you upgraded and a top mph.

[@JuiceMotoParts]

at some point i will post my personal bike and it surely purrrrrrrrrs!

[@crobulari2328]

Measure from the bottom of the stroke to the top of the cylinder. The top of the exhaust port should be lifted to about 2.5 mm under half way. Do Not go to half way !. The flatter the top of the exhaust port is the better but for longevity it is a compromise, so keep a little radius here. Lift the transfer ports by the same amount that you lifted the Ex Port. You can if you are able to do it, make the tops of the transfer ports where you lift them into a Y shape. When your engine starts to crackle you know that you are on the right track. Loads of experimental work here. Loads of work and expense as well. Make the expansion chamber out of thin material so it can "flex" under the + ve and -ve return pulses. Return pulses at high revs are supersonic so get your ear protection on !!. Good luck.

[@neibeezy3587]

hey man the link doesnt work?are you able to fix this.really keen to do this

[@signalhillscooter]

Something that needs to be looked at if you are going to do any porting or casting flaw touch up is to port match the intake tube to the cylinder. On a lot of those motors the intake tube shape and port on the cylinder don't match, killing the flow from the carb, rendering a lot of the work to the cylinder ineffective. And port match the boost ports to the base gasket match the gasket to the ports on the engine case and then match the boost ports on the base of the cylinder to the gasket

[@JuiceMotoParts]

A few comming out in the upcoming week or so. Stay tuned!

[@signalhillscooter]

Great video too :-)

[@garyschoeller8769]

personally I was just wondering about the transfer port casting burrs, 2 stroke have not been my forte I have had other engines that have similar castings but were made that way on purpose for swirl flow or hard roll fuel patterns weird but true. so this answered my question it is just crappy QC on the transfer port

[@aaronreid5789]

you can also deck the cylinder to

[@mikesousa5298]

Right on thanks man! Now I wont have to dish out the cash for a jug from arrow! Haha

[@mr.motormaster9881]

just a little porting makes magic 💥💢💫✨🌟

[@Electrocycle300]

this is GREAT! thank you! Now our customers wont have to bother buying them from me, arrow motorized cycles, CR machine, or DAX! what a great thing you're doing here! and we wont have any work to do!! woo hoo! like a vacation from all that awful work! now, do you have a video on not having to continue paying our bills?

[@thecbc7658]

Hey um wouldn't grinding away only one side of the piston make unbalanced which would result in wear and tear of the piston walls and rings? What is your opinion on slipper pistons?

[@TulioGreenWizard]

whats the correct porting and upgrades needed for perfect hill climbing? (45º hills, rly steep ones) i wanted my 66 to be able to climb a hill without pedaling, in which is not the case, it cant in standard factory state

[@michaelmayo4258]

do you have a video of building 2stroke bicycle motor to being faster

[@reallee9385]

What kind of solder would can you use for a crank case bolt . One of the threads that hold crank case prongs stripped.

[@TheFrank5767]

I notice you are using a GT cylinder I only use the GT5A that has a 40 mm intake bolt spacing and a matching reed kit !What is the torque you use to torque down the head ? I was hearing 120 inch pounds and 80 inch pounds for the aluminum Fred head . what do you torque your heads down to?

[@madbasementlab]

sounds good to me

[@jgbelmont]

What are your timing numbers? What is the bore and stroke for the cylinder you are working on?

[@roudyroy1]

dont take anything off the crown of the piston... bad bad bad you have just unbalanced it, do it all via ports.same as the skirt.. it provides stability on a 2 stroke piston. intake ports should be smooth, you want to reduce turbulence in the ports. the a/f mix hitting the crank counter weights is more than enough atomization. if these cylinders were plated you would of destroyed them. if you guys want power, look into timing advance, REAL porting, shaved heads and bored carbs. then jet right and put a good tune pipe on it and your rocking.

[@MattDemery]

do you have a video that can better explain this?

[@warphonesS22]

Hello I need help! The kit I purchased won't run right. I took off head and noticed that at BDC MY INTAKE ports are not visible. Is that normal? Did the wrong piston come from factory? I have the low hole piston. I can't find information on intake ports and BDC. Or pictures of BDC with piston relative to ports position.... The motor would start but not rev past 1000rpm felt like it was starving for everything.....

[@JbassPlayer28]

you have one thing mistaken: although making the intake port rough will increase fuel atomization and may slightly increase efficiency, it will actually hurt power because it decreases volumetric efficiency (breathing capability) of the engine

[@robertsmith5323]

BINGO

[@gunnyusmc89]

listen my bike is running extremely good on the top end but my take off is kind of sluggish can you advise me on my next course of action to fix this please advise

[@davidjsherwood]

any videos of your results?

[@codybain2955]

i had to cut off and file them flat on the bottom of the jug to make it fit onto my motor, should it still work? it will only fire if i dump gas down the carb :(

[@joshuaireland5181]

+JuiceMotoParts what if your exhaust port is round?

[@gkcoupe]

but was able to do 90 percent of the things covered in the video.... i even widened the gap on the piston where it opens up for the transfer ports directly below the pin on both sides.... i port matched my intake and exhaust as well as widened my gaskets to better fit the flange for both intake and exhaust....

[@rodwilson2114]

read power tuning two stroke engines,.....it will explain all

[@iownudie108]

How well can the transfer ports be reached with such setup (dremel's flexshaft) and what tip to use when doing that? Ps,you shouldn't raise the intake port,you should lower it so fuel mixture can reach the cranckcase earlier :P

[@troymays6300]

Got to think is a kid doing it the new generation most do things backwards but at least ain't playing video games all day he's at least trying just need someone that actually knows mechanics to tell him the right way to go

[@talkinglock]

what is the song at the start? i like how it sounds!

[@dailegribble9842]

Porting and polishing is very important in achieving a crisp rpm sweep in any high compression engine weather it be 2or 4 stroke the small pitting in the intake port can and will collect fule wich will cause premature defamation and if this occurs during the exhaust stroke this can lead to premature ware of the rings and cause blow by and cause bearing and or lower end of the case to become brittle and crack never remove material from a piston as this will cause week spots in the piston and more then likely cause the conecting rod to push up and threw the piston and can cause poor combustion cloging the intake and exhaust. Ports causing even more Los of power if u want to gain power there are dished pistons for these motors that will give you more power and best to upgrade to a exapantion chamber and go up a size or to in ur jet size also to adomize the gas just go to ur local hardware store and buy small fine copper mesh and use between intake manifold and jug with porting and polishing both ports will make noticble and reliable power

[@str8roller_6801]

How would I install the mesh without causing an air leak?

[@justinchampagne2818]

want to hear your opinion on this rod to ZMN80 I never seen one of these rods you know anything about him I got one on my engine

[@Ro-Bucks]

Another way if your on a bug and don't have the tools for porting. Add an extra gasket or two to where the jug meets the crank case witch will raise both the intake and exhaust but then you need to save the top of the jug and head a bit so the piston come back to the top of the jug. I didn't explain that well sorry

[@osaelbarrantes8060]

I wonder if raising the exhaust port could damage the cylinder at high revs per minute, as it gets so close to the limit.. I suppose you must not file so close to the limit.. Am I right, and does porting force the engine to use more gasoline??

[@warphonesS22]

Lol people are so butt hurt about this video. Complaining about everything. But people remind yourselves! These motors are $100 from damn China....... Anything you do is going to help increase power and efficiency. These motors are not freaken Porsches.. they are dirt cheap toys.... They don't need rocket science to run better.....

[@brendvandenbussche2665]

Can you reuse the head gasket?

[@gavicada1772]

So if gas go in crank case better make smood intake so fuel go easy in and lub parts when finish it will be atomized i think but we need to see some tests

[@TheDanielroberts]

Wow, this guy is a genius, I anticipate a comeback of two strokes due to the improvements that this one person has made towards an otherwise defective engine (obviously manufactured by complacent hacks). Is it possible that he has deferred from NASA to pioneer in his own expertise (the blue gloves were a giveaway). Gremlins are the cause of the scoring in the cylinder and shoddy workmanship, also the cold and flu medication he is taking is responsible for making him sound like he is completely clueless. All that aside, the man is truly advanced in 2 stroke engineering.

[@pjneslo8979]

TheDanielroberts- Do you actually think you're funny or being cool? Post something that makes you the fucking expert you claim to be or how about just keeping your ignorant comments to yourself.. The Balls of some people, fucking hypocrites!

[@chrischarters376]

Tosser

[@johnt634]

It's sad when you are to dumb to know that you don't know jack. Give the guy an e for effort . Most of these cylinders are crome lined, that flake easily. The next hot tip will to be chamfer the rings, so they won't hang on the ports. Relax people, we're just trying point out errors.

[@patrickwoodward6597]

Thanks. I have a extra motor laying around. is it okay to use the top ring only? (I broke one)

[@RJ-zr9ss]

Thanks for the info, and trying things out. Wouldn't an easy thing to do just be adding a bigger carb and tuning it? Like put an 80cc or 100cc carb on a 50cc engine, to get more fuel and open inlet port crossection too?

[@MrJameslewis530]

what do you think about Lucas 2 stroke oil? is it really better? thanks, Great Videos. I liked and subbed, and viewed about 10. very informative. i'm the only one on KZbin with Wheelchair wheels on a motorized bike.they work incredibly well. 8^)

[@jamest.5001]

what's the name of your channel? I'm gathering parts for a motorised bike build project. I have a 26" mongoose. with full suspension. and I'm trying to decide weather to go gas or electric. or both!

[@P8FPV]

Wouldnt that unbalance the piston?

[@davidgiffordsr.930]

When replacing the piston on a 49CC engine, does the "3" on the top of the piston come closest to the Exhaust Port?

[@YorHighness]

Piston ring pins toward the intake ignore any other symbols.

[@miguelhuertas7769]

hello is true when you porting you always go down never up

[@paullynch7672]

I'd like to see some work done,,,

[@JS-fb6ww]

Do i need make a third transfer port on the cylinder for my rse reed valve setup and windowed piston?

[@originaLkomatoast]

If done properly, adding a finger port or two from the intake port to the same level as the transfer ports would increase transfer flow. It could even be a tapered notch beginning at the transfer port level and increasing in depth to the intake part. The ports complement the fuel flow into the cylinder and help to push the exhaust gas out the exhaust port much like the airflow from the transfer ports do when it collides at the back of the cylinder and the only place for the air to go is up the cylinder wall towards the head pushing the exhaust gas out. The finger ports give it a slight head-start on the process of forcing the exhaust gas out the exhaust port. More exhaust out, more fuel-air mixture in.

[@johnt634]

Some call it a boost port.

[@seasonedtoker]

Beware, carbide bits will chip nikasil off cylinder wall

[@l.shumkov7468]

so which side is it? exhaust or intake ....... ??

[@jayvlog9841]

You how to asssebly that exhast

[@damnthiccassboye7138]

is widening the exhaust port going to make the piston ring dilate and gaught into it??

[@marthamryglod291]

There's a limit to widening but it's not a problem on these jugs.

[@Snatch19882]

Dwainpipe 21 is right, raising the exhaust port lenghtens the exhaust port cycle.. and btw Dwainpipe raising will "always" give you more power ,but your right ..you can raise it so much, than you hit the limit of what your exhaust can correct.. and you lose compression by raising the exhaust port.. So there is a limit! And the guy complaining about giving secrets away.. boy i would not like a cylinder ported by your company..

[@miguelcontreras192]

What top core is that

[@ricko56]

je l'est déja fait sur un peugeot 103 vml de 1985 , agrandir les transfers , l'echapement , admission , mais il y a des cotes a respecter , poncé la culasse a 1mm , carbu de 15 , pot sito chrome , 95 km/h elle a toujours fonctionné , essence huile 6/

[@sirirymond4482]

i need to upgrade my 2stoke 3wheeler engine for race

[@jasonsweet1868]

Does anyone know why reed valves work

[@willkilla]

Have you guys tested extended intakes?

[@hvguy]

porting the piston? im not for certain but I believe you have to install a reed intake. Not for sure though.

[@StephanSmith-sm7oj]

Hey man that link in the description isn’t any good anymore

[@tjdukes7452]

Can u plz tell me what the number on the piston means mine has a 3 on it ....i need to replace the cylinder i wanna make sure to get the rite stuff ....its a power king kit ....

[@d4rkhound388]

+Tj Dukes 3 is probably just the different CC's the manufacturer had for the engine.

[@tjdukes7452]

+GHOST thanx

[@integrationofmanandmachine4714]

Next engine honing?

[@honorb4glory606]

You should clean all your individual engine parts, with warm soapy water, before assembly. This will get all the dirt, dust, metal, and grease off; which prevents damage, and gives the oil a nice clean surface to stick to. Never use solvents, as they can penetrate into the metal, with several negative side-effects.

[@kennycayocca5658]

Use Tide to wash. Parts.

[@markplaylist5984]

I've never used soap, just shop towels degreaser wd40. I'll stick to what I know.

[@hemisrtjones4654]

Mines have no spark any ideas

[@RevAldea]

Then students need only to port the "inlet port" of "piston inlet ported engines" where you can grind and almost leave it in an unpolished state for test reasons until you have done then finish the polishing of the cylinder edges. This place is not ring touched In almost every engine I've ever seen. But always Clean the metal particles out before starting the rebuild your engine. For that matter just clean the whole engine's part completely, then "Do the whole Rebuild" completely.

[@kenzo5716]

you can raise the piston to the top of its stroke and look through the cylinder intake and the piston ports will be slightly smaller. I take an awl and scribe a line directly inline with the piston, then I simply grind the piston port to the size of the cylinder port.

[@Joe_Rebel]

so u can round it and piston rings wont get caught?

[@IamPzo]

what if transfer port wall break