Topping out at 20 mph...Too much fuel

tesjpurple · Feb 7, 2012

Bought a used bike with a 48CC engine and I have been having the same problem as the this poster>
http://motorbicycling.com/showthread.php?t=5268
The old plug was as black as coal and I have also noticed unburned fuel at the muffler and the muffler appears to be modified (thinking about ordering a new one). Running a mixture of 32 to 1.

I have ordered a new plug, I'm sure there are no air leaks, I've adjusted the float, and noticed that the cover on the ignition coil is split with the wire exposed (waiting for a new coil) and a new motor mount for the back of the motor (currently missing/also on order). Unable to test the changes until the new parts arrive.

Can anyone advise what I should set the plug gap at? Anything else I should look at regarding the problem?

Installed the new parts today (plug, ignition coil, motor mount) and still having the same problem with the following changes;

If I adjust the float down (just slightly) I get no fuel though if I adjust :-||

it up (slightly) I get fuel running out the air filter.

Edd · Feb 26, 2012

Try riding without the air filter, but only do a short test ride (just to see if there's any difference, make sure the engine's warmed up before going for a speed test). I found my stock air filter choked my engine of air at higher RPM's. It really held my engine back with poor acceleration and top speed.

bairdco · Feb 26, 2012

plug gap usually works best between .25 and .30.

for your problems,

your exhaust might be plugged up. while you have the pipe off, you can port-match the flange for better flow.

your air filter may be dirty.

floats may be set wrong. it shouldn't be pouring out of the carb. offhand, i can't remember the factory setting, sorry.

engine may be loaded up with carbon deposits. take the head off and clean the cumbustion chamber with some carb cleaner and a wire brush, and you can do the same to the piston by setting it at TDC so no crap falls into the cylinder. now would be a good time to replace the head gasket and torque it all back down correctly.

i was gonna say it may be an airleak, but you say there's none.

make sure your wheels bearings aren't seized up, and your brakes aren't dragging. may sound stupid, but it could happen.

can't think of anything else right now...

rustycase · Feb 26, 2012

My fabulous 48 was abt the same way when I brought it home in pieces...
It was running real fat.

It takes some fiddling with the float to get it right. at least mine did.
Then yah gotta go through the jetting thing on the cns.
Get some number drills, find what drill fits well, solder the jet closed, and drill it a size or two smaller. Begin with the needle clip on 2nd from the top.

and everything Baird said...

Best
rc

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Topping out at 20 mph...Too much fuel

tesjpurple

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Edd

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bairdco

a guy who makes cool bikes

rustycase

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