Off idle hesitation

If I nail it off idle it falls flat till I let off and it will catch up but it is very annoying and has almost sent me over the bars in a couple of situations. Does anyone have this problem or know whats wrong? I live at about 8000ft. and it was jetted by the dealer and they say that all the wr's and yzf's do it up here and they dont know whats wrong. Any suggestions would be welcome.

Thanks

Josh

The jetting is not right. My WR 450 did it after the airbox mod. I'm no expert but I would start with the spark plug to give me a true indication of the jetting. Check the archives on jetting at you elevation. These bikes come extremly lean from Yamaha. Check LarryCO, post he is on the right track at your elevation. The very first thing I would do is run it and then check the plug. If its white you are too lean. If its black soot you are too rich. You are looking for a tan color on the electrode. The symptoms can be very deceiving. check the spark plug first.

Four strokes are known for a little hesitation off idle. It shouldn't be that bad though. You can get it to where there is just a little bit of a hesitation. It is something you will have to get used to especially if you are coming from a two stroke.

Four strokes are known for a little hesitation off idle.

That might be true for carb bikes but not the FI bikes. There is absolutely no hesitation on a Dale even if the weather or altitude changes. It's probably part of the reason why Cannondales holeshot so well.

Optimum-power makes an FI kit for Yamaha's which might be something to consider someday.

Is your gray wire cut? Mine did that as well no matter what jetting changes I made till I cut the gray wire.

Definately look up LarryCO's jetting. I switched to it a while back and there was absolutley no bog or hesitation. I've done most of my testing at 8000 ft. I started having issues with the bike fouling plugs after a while though. Larry and I talked and figured out that the only difference in mods on our bikes was that I had done the ACV mod. I ended up switching back to the EKQ needle and haven't had any issues with fouling plugs since. I put the ACV mod back to stock and will test how my bike runs with the EKP needle again soon. Proper jetting will cure the hesitation. If you haven't switched to the E series needle yet, you should, it will help a lot. :)

Also, the GB/BK mod to shorten the duration of the accelerator pump squirt will help with the hesitation when you snap open the throttle. You can find out how to do it by going here http://motoman393.thumpertalk.com/

Thanks wicked I am gonna make some changes on it this weekend.

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