Post by denches on Dec 25, 2011 6:54:49 GMT -5
My BUYANG 300CC ATV missfired/backfired at low RPM's every time I accelerated 3 to 7 miles per hour but not any more. Heres the fix.
Some Chinese carburetors look like their sealed, no screw heads to get at the main jet and idel. I put a round (very thin ) metal cutting disk in my roto tool and cut straight slots across each screw head. Thus enableing them to be backed out with a screw driver for cleaning the carb bowl. In addition theirs a plug (brass or aluminum ) on the outside of the carb, almost a quarter inch round that covers up the set screw needel jet. I removed the plug, (drill a small hole in the center carefully just threw the plug and used a screw extractor in reverse it came right out). This set screw maximises the RPM's and smoothes out the engine. They put a really stupid head on the screw, 3quarters round one quarter flat eighth inch high. I managed to get it all the way out with a tweezers, ground it flat, cut a straight slot in it for a standard screw driver and screwed it right in snug, backed out 2 turns. I can now access the set screw with the macine running. As I backed the screw out I couldn,t beleave the engine performance increase and adjusted the idel down several times. Trail and error till you get it at max RPM's.
PS
Theres a how to U TUBE video for this: Chinese ATV carb clean deregulation
Some Chinese carburetors look like their sealed, no screw heads to get at the main jet and idel. I put a round (very thin ) metal cutting disk in my roto tool and cut straight slots across each screw head. Thus enableing them to be backed out with a screw driver for cleaning the carb bowl. In addition theirs a plug (brass or aluminum ) on the outside of the carb, almost a quarter inch round that covers up the set screw needel jet. I removed the plug, (drill a small hole in the center carefully just threw the plug and used a screw extractor in reverse it came right out). This set screw maximises the RPM's and smoothes out the engine. They put a really stupid head on the screw, 3quarters round one quarter flat eighth inch high. I managed to get it all the way out with a tweezers, ground it flat, cut a straight slot in it for a standard screw driver and screwed it right in snug, backed out 2 turns. I can now access the set screw with the macine running. As I backed the screw out I couldn,t beleave the engine performance increase and adjusted the idel down several times. Trail and error till you get it at max RPM's.
PS
Theres a how to U TUBE video for this: Chinese ATV carb clean deregulation