Project 49 - Cylinder Porting And Adjustments ( Minarelli Two Stroke Scooter Tuning )
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- เผยแพร่เมื่อ 26 ก.ค. 2012
- This video shows the process and results of cylinder porting on my 49cc Minarelli / Jog 2T scooter. For all of the details, tips, and tricks, visit www.49ccScoot.com
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Did pretty much exactly the same thing a few years age. Found that CVT, free airbox and richer jets made a big improvement (was blowing carbon sparks from exhaust on first test...) didnt to much to the piston dimentions but did a rough blueprint and found that they were a bit out from factory. Also changed the CDI module, on stock exhaust cut open and de restricted (as i couldnt be bothered paying for or building a pipe), was getting about 75-80km/hr on flat with good pick up. Theres a windows 2stroke pipe design app thats free on the net that is very good to match to 2strokes if you have all the specs, which you do. Nice work!
Badass. I was thinking that the pipe would help as it went along. Very informative. Keep em coming. I am thinking of getting a two stroke myself, and building it up to 90cc. I have seen some very impressive results with these two strokes.
Oh ok thanks👍 expert!! I'll see if the rotor will help and some new jets
Nice job. You have increased exhaust port timing quite a bit and you also need to consider the pipe tuning. I do port mod in nitro engines and this is what happens when I take an off road engine and port it for more revs. Just change pipe and bam power band is up way higher. Also with nitro we can mod crank duration to cram more mix in.
When you change port timing it al5ers the resonance frequency / pipe setup. You will need a better pipe to see gains from exhaust duration increase.
Hopefully when you change the cylinder you don't forget not to throttle as soon as you turn it on and leave it to idle for 1 minute, turn it off, 5 mins later leave it for 5 mins, wait 10 mins, leave it for 10 mins and then for a good amount of km going 30km/h will give you maximum power because the cylinder will be used to the engine as it's new.
No because it will run very lean at idle
I tried my best with a flexable shaft dremel and about an inch long carbide bit. I guess i messed with the velocity because i tried to get deep down in the trasfers to try and make it nice, flat, and get as much power for a pretty wide chamber racing pipe. It worked good with the stock mag/stator. BUT I NEED HELP!! MAKING ME CRAZY i got a polini sport 70cc bore with overboard porting just like the one i said earlier^^. The exhaust and boost port are the only 2 ports that sit lower than all the other ports. Does this mess up the bore from reaching its full potential? Im about 1-3mm off from the pistion making bdc with the exhaust and boost port because bdc the rest of the transfer ports match up with the top of the piston except the two that i was talking about. I already put 4paper gaskets and 1metal gasket that comes with the polini bore kit and compression sucks even with a full circle crank. I dont really care about the compression until i look foward to shaving the head, but is that safe to run it like that? Even with the O-ring? Top speed was 60mph with a messed up jetting and stock gears but will gear up soon, and will be getting a performance stator and mag so it can reach higher rpms, that can also be a problem too. I watched videos with this bore and they sound good. Got any tips if i should raise the bore anymore or just straight fix the jets? And also try to install a performance stator/mag first?
Any time you're moving the bore around you should be measuring port durations to see what effect you are having on them. A little spacing can make quite a difference in port durations. Some info about that here :
49ccscoot.proboards.com/post/30229/thread
With the o-ring head you'd prob either end up milling the head so there's no longer a receiver groove and use copper spray or a metal head gasket or if there's some of the groove left I beleive some use high temp RTV in there to help it seal.
If it's doing 60MPH with incorrect jetting I'd say you're doing alright though. Maybe just work on the tune and see how it does.
u need to fit correct roller weights when u do any porting; with that port timing roughly and a nardo pipe mine ran at around 11,000rpm.
So you ported the exhaust hole but didn’t grind any off the top part close where the piston would be?
It's shown in the vid, but I modified the entire port.
i dont know so much englinsh can you tell me the best rsult for artistik 90 pls ?
I don't know about that model, but if it's a 90cc two-stroke, then see if you can use google translate on this page to get some info :
49ccscoot.proboards.com/post/30229/thread
you should try to angle your transfer ports so the intake charge from each side is going directly at eachother. your probably losing too much of your charge out of the exhaust port because of the longer duration.
btw i should ask you a question,how did you entered the cylinder from the inside to port the intake? what did you used?
This did 40MPH GPS stock with basically a 300lb rider. I used to own the typical Chinese 49cc piston port engines like gopeds usually use, but in midbikes. No offense meant, but the case reed minarelli is a much better engine platform.
Isnt 2stroke banned from america? Or just mopeds can run? Nice and professional job man :)
for wich types of scooter?
Did you notice the title and description by any chance? Don't mean to sound like a smartass, but the type of scooter this is for is there. Minarelli Jog 1E40QMB 2T powered scooters.
i rather lower the wiigths in cvt , u take 1km to get in some speed,
Your exhaust cylinder hole should be about 70-75% of your exhaust port hole size, you should not enlarge it to match your pipe hole because you loose velocity and probably thats one of the reason for worse performance
Holy cow that thing is well slow! My GoPed will do like 40mph stock!!
of course there is no point in porting out your exhaust port if your going to use your stock exhaust pipe its just going to clog up your ported exhaust manifold