First MB Build. Help Needed.

A few questions.

Ok, so I have no problem starting the engine. I have to put the choke down more than half way to get it running. Once the engine starts and while the bicycle is in motion, the engine idles fine. However, once the bicycle decelerates to the point where it's almost stopping, the engine dies with it. Is this normal?

I've also noticed that my bicycle doesn't really pick up speed. I could only make it go up to 17 mph on a downhill, which is laughable at best (I know I can pedal to reach that speed). Do you think there is an air leak somewhere around the carburetor? One thing to note is I completely took off the air filter cover (the black plastic thing) because it's the only way the motor can clear inside the bicycle frame. I left the flitering on there along with plastic slide that was inside the cover. I assume it's no big deal since the engine starts up fine.

Any help with be greatly appreciated

When your stopping do you disengage the clutch? You need to pull the clutch in if not the engine will die when you go very slow or stop..


Also an air leak might also be your problem for your second question.. Or its just new and needs to be broken in before the power really kicks in..

Ok try this.. To check if you have an air leak..


Ok.. First i want you to start your engine like you normally would and then pull the clutch in and then let the engine warm up for about 5 minutes.. After that pull your choke lever all the way up.. THE engine should die immediately if all is well..


Goodluck with your engine.. Hope i helped..

And also you should not ride your bike without an air filter you wouldn't know what could get sucked in and kill your engine.. Some of the guys here can help you fix that problem with the air fliter not clearing your frame..

Is the engine a 2 stroke or 4 stroke?

It's a 2 stroke.

half choke to start is normal.

as for the air filter set-up, you say you've got the black plastic circle and the sponge thing still on, but how?

did you cram the sponge into the carb and then bolt the circle on over it?

if that's the case, the sponge is probably blocking the air from getting into the carb, which would result in bogging and your motor dying. it would go slow, because it's not "breathing" properly.

and when you say you slow down and it dies, you are pulling the clutch in before stopping, right? these motors won't idle without the clutch (if you are, don't laugh. a lot of people think the clutch is just for starting it or rolling the bike when it's off.)

Thanks guys! I disengaged the clutch and let the motor running alittle and put the choke all the way up. The engine died immediately, so I guess I don't have an air leak .

I took the sponge and the plastic thing off the carburetor and now I can hit 20 mph going up hill. Now to find something to filter the air w/o blocking the air flow... hmmm

This is what I did, talk about a tight fit and you can always do yours where you need it smaller, just a idea