Chosen Solution

I have a brand new 66cc motor kit that mounts onto a bicycle frame is known as an 80cc Skyhawk but in Canada it’s 66cc. I used a High-Performance carb but I couldn’t get it to idle slowly with that carb I backed the idle screw nearly all the way out and the engine ran faster and then it blew the spark plug right out of the cylinder head. In response to this I put the stock carburettor on and now she runs fairly well aside from the fact that I can’t throttle past 1/4 throttle and it sure would be nice to be able to get the rest of the power from the engine. Everything is brand new when it’s idling she purrs. Another thing that happens is when I throttle down the engine takes a few moments to idle down which is odd. When I am riding and try to go past 1/4 throttle the engine slows down and I may as well be peddling but at 1/4 I can get to around 30 KPH but she can go faster if I can figure out what is causing the issue with either carburettor but I am not sure what problem I am looking for and am hoping someone can help direct me.

i would put the performance carb back on just right send it on the spark plug like tighten her down real good or sometimes the choke is on the throttle and you messed up the linkage so double check all that

Check to make sure you don’t have a leak on the intake manifold or the manifold side of the carb’. you can check this by dribbling a little oil along the joint to see if it gets sucked in. If this is the case, then the engine will be sucking in air without the petrol vapour to ignite and so causing a ‘flat spot’.

it could be getting too much air from a leak somewhere

I’m having the same issue brand new engine brand new carb all set up corre you but bogging down

Remove your air filter temporarily. Does this help or worsen the symptoms you described?

On my 50cc 4 stroke I had a problem with it bogging down at full throttle. But when I’d let off the throttle a little bit I could feel it accelerate a little. Problem was that it was getting too much fuel. All I had to do was adjust the air/fuel screw.