Would like to make my 100cc 2 stroke engine gain more speed

BeastMode84

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Feb 22, 2024
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Strawberry Plains, Tn
Ive put my 100cc engine on a stingray bicycle got a wide tire in front and narrow tire in front. Had to modify the frame (added my own motor mounts) to mount the engine. Had to add 4 more links to the chain. Had to modify the chain tensioner as well. I'll I have ordered disc brakes I'm waiting on them to come in the mail. The normal rubber brakes that came with the bicycle wasn't doing the job.

Now my question is.
Is there anyway to get more out of the motor? (go faster) it goes about 20-25 mph already would like to go 30-35 mph
 
I gonna be posting some pictures soon
To be quite honest from honest experience from building on these you're going to retard the motor around that range without modification because the rims are 24" front and 20x4 in rear.
 
Furthermore I lowered my sprocket size to 33t & 20t crank for the motor. I used to run a 41t and it had higher end rpm but lower was crap. Right now in testing s Phantom 85 v3. I haven't fully broken it in yet so I've yet to try to full speed it. But I'll definitely let you know.

Tuning motors depends on raising the exhaust porting and upgrading the exhaust in the cylinder. Plus some find port work. You may get about 50mph max. Look around YouTube for some guides. Be attentive, take others experienced advise otherwise here.
 
Ive put my 100cc engine on a stingray bicycle got a wide tire in front and narrow tire in front. Had to modify the frame (added my own motor mounts) to mount the engine. Had to add 4 more links to the chain. Had to modify the chain tensioner as well. I'll I have ordered disc brakes I'm waiting on them to come in the mail. The normal rubber brakes that came with the bicycle wasn't doing the job.

Now my question is.
Is there anyway to get more out of the motor? (go faster) it goes about 20-25 mph already would like to go 30-35 mph
Do you have a stingray or an OCC? If you have an OCC then 25 is pretty good for that engine.
 
Most of the "100" style engines aren't really known for top end horsepower, and the work/money you need to put into it to achieve that extra 5-10mph might surprise you. A decent pipe and port work is going to be a lot of it. A lot of the times the port timing ends up being a compromise due to the original port placement in relation to the combustion chamber, which is hampered if you are trying to correct the squish gap to get higher compression. You would be better off starting off with an engine like the Avenger 85 or Phantom 85 that can easily pull 30-35mph. My Phantom will part throttle cruise at those speeds with my giant butt in the seat.
 
I slapped an Phantom 85 v3 on my Schwinn Stingray OCC. It's highly modified. You can see the work here:



As for top end speed. Phantom 85 v3's are 50mph out of the box. Of Course you have to properly break them in i haven't gone over 35mph yet. Just as a reminder. I wouldn't recommend going over that on these frames. I snapped one frame and had to replace it going 45 on a china doll 66cc. yd100's can be a little faster as ImpulseRocket mentioned but their more of a powerhorse for long rides than the longtivity of faster speeds. As mentioned to many mods. The importance of raising and widening an exhuast port is what highly impacts the speed of a motor. This is why the Phantom 85 v3 is such a great motor out of the box. It out preforms my Minarellis in every aspect so far. Low and High end Torque and is more reliable.
 
On a side note if you're running on an actual oldschool Schwinn Stingray. That's rad and also a very expensive bike!
 

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