Can't get engine to run right

[HENDECYCLE]

Hey guys. I'm 17 years old and this is my first build. I'm building a sort of board track racer style bike, but I'm at a stand still right now because I can't get the engine to run right.

I bought the black 48 cc engine kit from luckyearlybird on ebay. When I first put it together, it would take about 10 tries to get it running fairly well, but I couldn't get it to go more than about 10 or 15 mph. After a while (15 or 20 miles over a week or so) it started to make these weird sounds and lose power.

I thought it might be something to do with the air/fuel mixture, so I tried to adjust the idle screw and no matter where I adjusted it, it still would not run right. I thought that the carb might be dirty on the inside, so I took it to my auto shop class at school and cleaned it out and sprayed it with some carb cleaner. That didn't seem to help either. Then I thought the oil gas mixture was the problem. I was using about 16:1 so I switched to 24:1 and that didn't seem to help either. Then I thought it might be the spark plug, so I bought a NGK plugs and that didn't really do anything...

Now when I release the clutch, the engine sometimes won't start up and will almost stop the bike - it feels like it drags it to a stop. And when I do get it to start it has this klanking or knocking sound coming from the engine. I took off the cover on the left side where the magneto is and there were metal shavings in it.

Does anyone know what the problem could be? - I don't think it's the carb or the spark plug.

Thanks!

 

[crassius]

sounds bad - with left & right covers off, try (gently) prying each end of the crankshaft up a bit - if either side moves, you've lost the main bearing on that side

if those are OK, then maybe your stator or rotor is misaligned and is rubbing together - you should be able to straighten that out OK, but while it is off, check your seal on that side for damage too

 

[wan37]

Sounds like he sheered the key way on the magnet and timing is out of wack that what happen to me .I had a new engine do that same thing with knocking.I fixed the key way and it ran fine but I did not run it very long when it started knocking shut it right down.