2004 YZ 250F with Dr D System White Bros Air Filter.

With stock jetting i was getting a lot of poping on decel but my bike was snappy without any hesitation and running very fast out of corners in 2nd and 3rd. I could roll through a burm at idle then snap the throttle and have instant power.

I switched to a 45 Pilot Jet and the poping is gone but the bike feels sluggish and bogs out of turns and hesitates coming out of burms in 2nd gear? I go to hit the throttle it will bog out. then all the sudden power with hit? is the larger jet adding too much fuel? The bike doesn't feel as lively with this new jet. Not as crisp. I missed a couple doubles and cased it pretty hard due to this problem...

I have the quickshot too.

I probably need a new top end but should i just run the 42 Pilot with poping on decel? Its not terrible and a Chad Reed Yamaha team rider was training at my track yesterday and his bike was poping pretty good on decel as well?

Is it a give or take situation?

I have a fuel screw and haven't touched any of the other jets or needles.

IF you think you may need a top end, there is no since doing any jetting or adjustments until the basic mechanics are right, do your top end first, then work on the jetting, if it is still an issue.:naughty:

CLUTCHLESS said:

did you have the quickshot the whole time, or was that something that was added at the same time as the 45 pilot jet? I'm not hating on the quickshot, just trying to determine if that's a factor or not.

Have you tried turning the fuel screw back in, now that you have a fatter pilot? Go back to stock on that, maybe a turn in. Something to play with to see what affect it has, to help make a determination.

have fun!

Always had the quickshot.

I played with the fuel screw as well.

i think i am just going to drop back down to the smaller Pilot see if that eliminates the problem.

I've been experiencing the same problem. I never realized how bad is was till i rode another 250f this weekend and it made my big bore feel weak down low and blubbery. I have a 45 and am going to go back to the 42 and see what happens. Might also lean out the needle a clip to see if that helps. I used to think I had to clutch it alot due to always trying to run a gear taller but I guess it wasn't the case!