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I purchased a 1998 KDX 220 about a month ago. When I picked up the bike it was in decent/good shape. The PO put in a new top end and replaced bottom end bearings and seals. No proof of the top and bottom end replacement, but I looked at the piston thru the exhaust port and it is extremely clean and the cylinder walls look good too. The compression is at 140 psi. It has a FMF Fatty Pipe and FMF power core2 silencer. Stock 220 carb w/ brand new (clean) 42 pilot and 145 main jets. FMF said this is the jets to use with this bike and their pipe. I run 91 octane gas with a 32:1 mix of Maxtor Castor 927. Brand new Plug (good spark), Air Filter is a brand new No Toil.

One thing I cant get past is. The low end is fine but it hesitates really bad before the power band kicks. I have messed around with the air screw according to the KDX jetting guide on the site. I have made it better but the hesitation before the power band kicks in doesnt seem right. So after messing around with the air screw for awhile. I took a look at the KIPS and noticed that the alignment is off by one tooth. Plus I think the PO didnt align the KIPS up right to the other KIPS gears. The piece with the horizontal teeth is pushed forward too far.




This is what I was expect it to look like



I am really reluctant to start tearing into the engine if this wouldn't cause the hesitation issue. Do you think this could be the cause of the mid throttle hesitation? Other than the mid throttle hesitation the bike seems to be fine. Starts fine, idles without any issues, top end seems to be a little weak but ok.

r_sixxer wrote:I am really reluctant to start tearing into the engine if this wouldn't cause the hesitation issue. Do you think this could be the cause of the mid throttle hesitation?

You want to correct the KIPS even if the hesitation was caused by something else. But I think you'll find that if you get it set-up properly, your bike will run fine.

Yes. You need to pull cover off other side and pull off pipe. Make sure right side is correct. If so loosen the nut on left. Push rod all the way in. Then turn gear till it sits in its detent notch and line up marks. Torque nut to 78 in lbs. Now looking in to the exhaust both subvalves should be closed. If not the head has to come off to re-time them. Hope this helps.

Thanks for the input. Looks like the head will be coming off.

This problem sounds A Lot like the same thing I had occurring before some carb work and re-jetting my bike. After the (definitely) correct jetting was done... Bike ran great. Obviously the KIPS timing is important but the carb & jetting is very easy to check.

02 - 220: Runs rough Before power-band
http://www.kdxrider.net/forums/viewtopi ... 77&t=16714

Cheers,
SD