White Smoke/Backfire

[b182tm]

Hey guys, when I start up my ATC, usually in the cold, the exhaust is white. It also smells kinda bad. I let it run for a bit, and then ride and it clears up right away. Does anyone know what that could be? Also, not related, I was just wondering what causes backfiring? It usually only happens when I'm in 5th gear and let off the gas? Is that normal, or is there any way to stop it? Thanks for the help.

Derek

[MTS]

Sounds like your Jetted on the lean side...you may want to give your carb a clean and re-adjust your A/f Screw for the white smoke (also check your oil for water) and check your Exaust system for any leaks........But top end def sounds lean if its backfiring......

[Erics350x]

backfire when you let of the gas, sounds like its loading up could be jetting or mixture adjustment. white smoke at start-up is usually valve seals/guides letting oil leak in the cylinder while its setting. does it only smoke after it sets for awhile?

[b182tm]

Hey. I cleaned my carb about 2 weeks ago, so it's very clean. Also, I just changed the oil, and there's no water in it. So is the A/f screw on the carb? I adjusted the idle screw some, could that affect it? And valve seals? Where are those, and is that a serious problem? It starts smoking right when I start it, and then it stops within about 30 seconds. Thanks for the help.

BTW, I'm at about 9,000 feet elevation, and the manual says to switch the standard main jet with a high altitude type (#90) above 5,000 feet. Could that be the problem?

Derek

[Erics350x]

valve seals arent that bad to change, but you have to remove the head. the mixture screw should be on the bottom of the carb. close to the intake boot. if its blueish white smoke its oil burning and carb adjustment wont help. does it smoke at every start of just when it sets for a couple hours?

[b182tm]

Hey guys. It is only after it has been sitting a while. And it doesnt seem to do it every time. Also, it is pretty much only white, no bluish...
THanks