Other Won't run once hot PLZ HELP

irst off I am new to this forum. Just got my first bike not long ago and just getting into the motor toys. I have a Chinese made bike( which is more then likely the issue) but its better then nothing. Finally got it running, but I have a few issues. When I'm about half throttle third gear the bike starts backfiring on acceleration and loosing power. And once the bike is hot it won't run at all, I get about 10-15 minutes of fun and then the bike dies out and won't start again until cool. Any input will help. From what I can see there is only one screw on the carb, and I have played around with it, the bike idles well and runs pretty good until it gets hot. Like I said any input would be great and appreciate the feedback!!
Thanks
 
Probably start with checking valve lash, most likely you'll find the valve clearance is to tight, the engine may start ok cold but when it warms up and the metal expands the valve clearance decreases to the point where the valve hangs open causing you hard starts and backfiring.
 
It sounds like the valves need to be adjusted.
Is that something difficult t
Start with a good carb cleaning and a valve adjustment.
OK cool will do! I've never shimmed valves before but I will do my best! I don't have a service manual, are there any typical specs for a 150cc 4 stroke or am I going to have to hunt down a service manual
 
Is that something difficult t

OK cool will do! I've never shimmed valves before but I will do my best! I don't have a service manual, are there any typical specs for a 150cc 4 stroke or am I going to have to hunt down a service manual

There's a service manual somewhere for it. I would start by googling the make and model number with the words "service manual".
 
two things come to mind, and you wont need shims on any of the air cooled dirt bikes that i know. if you find the flywheel rotor it should be marked with a few lines and letters. you should be looking for the one marked T. turn the rotor with a wrench and line it up with the case mark (usually pretty obvious) and see if it is actually on the top dead center of the compression stroke or the exhaust stroke. if the valves are depressed at all, turn the crankshaft a complete turn (360 degrees) and check again. if you cant get a loose feel in any position then you know they are too tight. there are adjustment screws and nuts for each valve. if you don't have any exact settings you can do as I do and start at .002".

I think your problem is more likely coil or stator related but you will need a cheap multi meter and and some specs to make sure. in the meantime y ou can set the valves and clean the carburetor and set the float. if nothing else it will run better in the 10 minutes it takes to die. cleaning the fuel filter and screen in the tank is also something you should try.
 
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