No power

66cc Skyhawk: I'm lost for ideas. My bike was running fine during break in. Now it will idle okay but when I apply the throttle, it bogs and the rpms don't increase much. I'm running it at 40:1 now. I noticed that there wasn't much air oe exhaust fumes coming out the exhaust. I have cleaned it with brake cleaner plus tried my old exhaust and still nothing. I've changed carbs, cleaned carb, adjusted e-clip, checked fuel flow, cylinder head bolts and new spark plug. This has me stumped of what else it could be. The magneto was still dry but I didn't check the seal. Could it be the cdi? I'm still using my old 1 from a 66cc flying dutchman.
Any ideas would be helpful. Thanks.
Stephen

2door said:

How's the compression? You could remove the spark plug and have a peek at the cylinder walls. Look for any scratches or gouges that might indicate a broken piston ring.
If you can't see anything through the plug hole remove the cylinder head and take a look.

Tom

Click to expand...

If a piston ring is broke, will it still have the proper rpms when applying the throttle if the exhaust is off? I fired it up with the exhaust off for a short period and it seemed to work properly.

2door said:

But how does it pull the bike and you? Just revving the engine, even with the muffler on or off is not a good indication of power. The increased noise alone might lead you to think the engine is running good. How does it ride with exhaust system removed??

Tom

Click to expand...

Without the muffler it pulled fine and had the rpms. I'll do another run tonight just to double check. I didn't go WOT when trying it out, just in the backyard.

I put the newer muffler in a fire for about 10 minutes last night, hoping it might clean anything else out that the brake cleaner didn't get. I haven't put it back on yet to try and see if it was the problem. I could feel air coming out of it when using the air compressor.