I have a Lifan 125cc engine with Mikuni VM 26-606 carb. Purchased new, only a few hours on the Lifan but it worked fine, stock carb was replaced because it leaked. Ran fine for a while after the vm26 was mounted but it was running a little rich when I checked the plug. I changed the main jet to #140 (based on what people had said in old threads) from the stock #190 and the next time riding the bike starts bogging down on higher RPM's. I put the #190 jet back in and nothing changed re bogging down so I then adjusted valve clearances to .004/.005 and bike is now hard to start and dies once it gets warm. Rechecked valve clearances and set them to .005/.006 in case I had them too tight but no change to engine behavior. Right now I have to give it gas to get it started - but will kick back and/or smoke from the air filter before it finally gets going along with some gas dripping off filter. Once running it will die after a minute or so of idling and cannot be started again for a few minutes. I noticed when I was setting the valve clearances that with the cam sprocket dot at 9 o clock and the t marked lined up that the flywheel doesn't want to stay there and tries to go either side so I had to have someone hold it - I read that was just the magnets trying to push it so dont think thats an issue, just mentioning it to be thorough. Rubber boot holding carb is tight. no leaks on the intake at any of the connections. Exhaust gasket doesn't leak. Only other change I made was a trail tech computer - but I took that off to exclude it when I started having problems - seemed to work fine with the LED lighting up and getting power, but the RPM with wire wrapped around plug and connected to the coil was reading around 4000 at idle (bike idle speed was normal so not sure why this is) Think the valve clearances are ok - but conflicted between different video's saying between .003 and .006 for the clearances so I went with the bigger clearance as that should be better than too tight? Next step I can think of would be to test or buy a new stator...? Any suggestions on what else to check would be appreciated !