Don't IC engines have torque and power curves? I think this engine is a good simulation of an electric motor, anyway to make it more like an IC engine?
Its a nice bike and its good breakability wise but...
Improvements You should make next time;
More to scale, find the size of the actual bike and then make yours the same, more realistic.
Make the front shocks stronger, so they don't break as much.
Use less parts on the track, so it isn't laggy.
For rims use two gears with opacity set to zero and borders on, this looks like spokes. (See my Honda CRF 450 dirt bike scene http://www.algodoo.com/al … p?id=21100)
Add a rider, very hard but makes it soooo much better.
Overall i'll give you 8/10 for the scene because you obviosly put a lot of work indo it.
Give it a large flywheel on the crankshaft, it helps one cylinder engines run smoother, also give the spawners code that spawn the circles with the same velocity as the car, this is your problem.
It happens because your spawn engine spawned heavy objects at a velocity of zero, meaning the car had to accelerate the heavy objects using its own momentum, also your engine and drivetrain had lots of friction.
There is an easier way to do it; point a laser at one of the gears and put in the oncollidecode;
"(e)=>{scene.my.rpm = (readable(owner)).angvel / (2 * math.pi) * 60}"
This is the only code you need. (and it is in rpm's)