I got my son this mini bike from a garage sale with this JF168 engine like others in this board i cant find a repair manual on it he was riding and it just quit running now all it does is backfire into the carb. it was running good i have check all the basic 4 stroke engine stuff air filter,plug,fuel,fuel filter,oil it fires every time you pull it but will not start. If we do happen to get it to start it will run for a few seconds at the most and starts backfiring and acts like it is not getting any gas the guy i got it from said it was sitting for a while so we did the whole new fluid thing oil,fuel filter,dumped old gas added fresh was running good for days then this i have also pulled the bowl off the carb.checking for junk in there and it was clean and fuel flow seemed fine
could this be a shear pin timing issue with the flywheel
also if anybody out there has this engine on anything could you plz post the spark plug number here
not sure if the one we have is the right one looks really long for this small engine but i'm more up on B.&S.
P.S. i found the manual online at the companys web site BUT you need a username and password to get it http://jdshanghai.com/DownloadCenter.asp#
I also emailed the name on the dowload center for some help with maybe getting the manual
thank you for your time and help