any one know why it will backfire and die when i turn the choke off but run finr with it on.not just one backfire sounds like it has glasspacks on it thanks Ron

 

check you jetting, its just a guess.

 

you need a bigger jet my man

 

Unless you've just done some mods like changing the pipe or airbox you don't need a bigger jet.If it ran good before with this jet why would it suddenly need a bigger one?You must have a restriction somewhere in the fuel delivery.Pull the gasline off of the carb and make sure its flowing out of the tank good.If it is then its time to pull the carb off and clean it out.Also make sure the rubber intake manifold isn't cracked and sucking air as this is common on the 350 Yamaha's.

 

If you bought the bike at a different alltitude you will need a rejet, your carb might be dirty too.

I know one time my stupid parking brake wire was loose and my bike just backfired and sputtered and then died on me, i doubt thats it because of the choke problem your having.

 

Thanks for all the input I did no mods just load'ed it up to go out.so we go out and did all the things like check the rubber then the plug it has no parking brake clean the carb still runs like crap so I say ride like you stole it if it breaks then fix it rode it hard max RPM's then after 1/2 hr or so ran fine then died no power found the hot wire broke off fixed that and runs fine now so it was a bad wire