03 Big Bear rough idle

[ar200]

This winter gremlins have entered my garage both my drz and big bear are having jetting issues. I noticed the The Big Bear was not right during a snow day this year. It won't idle unless i have the choke on just a little. I have cleaned the air filter, adjusted the valves, changes the gas and tried to clean the carb. The jetting is stock I know the pilot jet is clean i have had it off and cleaned it twice. I have experimented with the air screw i thing it helped some but haven't got it right yet and don't think it will. The head pipe gets glowing red hot and it will back fire when letting off the gas after full throttle run it runs good as long as the gas is being poured to it. Think a new plug might help? I wouldn't think so since it runs good in under a load. I am open to suggestions. Thanks in advance for the help. I think it is a 33 mm Mikuni.

[jpentecost]

I am having the identical problem with my 2001 Big Bear right down to the red hot header pipe.

Did you ever get yours fixed? If so, what did the cause turn out to be?

My guess is that my valve timing is out. Probably the result of legitimate carb problems that are now fixed and a loose timing chain that jumped when it was running crappy due to the carb problem.

[DizGrizz]

The only way you can have your valve timing be off is if the timing chain jumps. If you have not corrected this, then there is no point in going further until you do.
If you have, then you are almost certainly running lean and prob still have a carb issue or an air leak after the carb.

[ar200]

Yes I got it figured out now. The Pilot Jet was clogged I use ethanol free gas, inline fuel filter and marine grade stabil to try to keep things cleaned up.