YZ400F Lots of backfire problem

Hi, I have a 98 YZ400F And it's been sitting in my garage for about 6 months and when I got it running it runs good but just has a lot of backfire and I'm not to sure why. It's not just backfire it's loud pops. Please help. Thanks

Try adjusting the pilot screw. Put the screw all the way in and go out 2 turns, then just adjust it from there.

If it sat quite a while, it's likely that the pilot jet itelf has a film of varnish deposited in the orifice that is effectively making it smaller in size than it's supposed to be.

If it sat quite a while, it's likely that the pilot jet itelf has a film of varnish deposited in the orifice that is effectively making it smaller in size than it's supposed to be.

My 426 was doing the exact thing. I cleaned out the jets and it runs perfect. Even starts by the second kick with no choke !

Grayracer gave me the same advice a couple of months ago.

Thank you Gray !

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