75cc "100cc" Build

My third gas powered build

I built this to be my road trip bike, it's bored 49mm with an iron sleeve. Port timings were perfect out the box! I made the exhaust out of a copper pipe and a baseball bat, the chain tensioner is a skateboard wheel. Put a scooter gas tank on it. Went over 50 mph (downhill) it was TERRIFYING

(I've got $90 in this bike)

I love it

 

[Gordy]

@Johnny_ got 53 outta his with adjustments to the timing

 

[Johnny_]

Great job!! 50 does feel very fast. I dig your pipe lol. I never woulda thought of that.

 

[Johnny_]

@Johnny_ got 53 outta his with adjustments to the timing

Doin' my bragging for me I see?

But yeah. Gordy's right. 53.5, not downhill. And not broken in. But I spent a heckuva lot more than $90 lol.

 

[Sidewinder Jerry]

I've gone 50+ mph on a 4 stroke 33cc engine going down hill. Gravity or strong tail wind assist doesn't count unless you crash then speed is speed regardless of how you got it lol

 

[DirtyBum]

@Johnny_ got 53 outta his with adjustments to the timing

Ok I got 34 on flat ground with the 44t sprocket and I haven't balanced the crank yet so give me some time lol

 

[DirtyBum]

Doin' my bragging for me I see?

But yeah. Gordy's right. 53.5, not downhill. And not broken in. But I spent a heckuva lot more than $90 lol.

I used a lot of recycled materials with a $65 engine couldn't be happier

 

[Johnny_]

Ok I got 34 on flat ground with the 44t sprocket and I haven't balanced the crank yet so give me some time lol

Yeah I can't imagine going 50 without the crank balanced lol.

 

[DAMIEN1307]

Yeah I can't imagine going 50 without the crank balanced lol.

Unless your motor is a Phantom 85...lol...lol.

 

[ImpulseRocket]

Unless your motor is a Phantom 85...lol...lol.

Which is why I balanced my Phantom.

Ok I got 34 on flat ground with the 44t sprocket and I haven't balanced the crank yet so give me some time lol

34mph with a 44 rear sprocket on 26 inch wheels is 8000rpm. I would say you did a pretty good job with your port adjustments if you got it to pull you to 8k. Definitely room for improvement if you want to get a little wilder, but I would call that a good healthy engine.