KDXRIDER.NET

Ok, so I thought I'd throw this out to the guru's before I just started tearing into things hoping that maybe you could help me narrow down a strategy first.

The engine setup '03 KDX220 Stock pipe (fresh repack), BR8ES, FMF Turbinecore II, Boyesen Power Reeds, Wiseco piston, standard bore (good compression), no carb or head mods. Carb fully dissasembled and cleaned 02/10

The issue: For the last 4 or 5 rides it has started stumbling in the lower rpm range and just won't clean out and rev smooth until you twist into the top 2/3rd of the throttle position. Initally only in 3rd gear and up, but now happens in every gear.

Rode with a buddy over the weekend who lives and breathes Gas Gas 2-strokes. We swapped bikes (He has a very sweet 300) and his impression is that it probably isn't the jetting as it is too significant a change in performance versus riding conditions (no elevation changes just warmer temps since it last ran clean) He is leaning towards it being reeds or power valve issue with a slight possibility that the needle and/or air screw may play a role.

Ideas oh wondrous ones?

The air screw is adjusted throughout the day on mine. Temp changes, humidity changes all change fuel air requirements.

I'd check power valves too. I had my bike out about 3 weeks ago and it ran perfect. Went out last weekend and it was stumbling pretty hard from midrange up. No changes in between, unless you count a fork rebuild. Played with airscrew and needle position and got no real improvement. I'm crossing my fingers that my dang subvalves aren't broken again. I'll pull the pipe sometime this week and have a look. If the valves are broken again, well.... might be time for a new bike. Those valves are getting harder to find, and the price to replace is about that of a new top end.

juliend wrote: If the valves are broken again, well.... might be time for a new bike. Those valves are getting harder to find, and the price to replace is about that of a new top end.

Will you get a '95+ KDX or go with something different?

Dunno, depends on what I can find I guess. My preference would be a 95+ KDX, but my buddies KTM200 is looking pretty good. He's wanting to get a 300, and I think I could get the 200 for about 1,000.

I'd rather figure out a way to stop the valve breakage and hang onto my old 200 for a few more years. I really love my bike! Especially now that it's practically brandy new from the bottom up.