i have a 200cc loncin quad (2003) that fails to start, i have checked the carb, air filter, put in new fuel and fuel filter, made sure the engine is getting fuel, its got good compression and a good spark (old plug and new plug), tried using easy start spray but still no joy. i bought the bike 2nd hand and it has only done 289k, when i first got it it started straight away but gradually started to take longer and longer and now nothing, it sounds like it wants too go but for some reason wont. i have managed to bump start it but as soon as you let off the revs it dies. HELP anyone any ideas

 

Well as strange as it sounds we had a loncin 110 would not idle after taking gas tank off I could see the throttle cable going through the top of carb, when we throttled it the top of carb also lifted screwed top of carb back on ran great good luck

 

I had the exact problem with a loncin 70cc motor, i had good spark, good compression, new carby and timing was spot on. When i pulled top end down to check valves they looked fine too. I noticed when putting valves back in that at Top dead centre the inlet valve clearance was tight, I reset valve clearance put back togeather and started straight away. I would check valve clearance just to eliminate it. hope it helps.

cheers