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You aren't suffering fuel starvation if you're pinging. And the overheating is probably leading to your pinging. Make sure your cooling system is operating correctly. I'd check coolant level and if low look at the water pump and seals first. Eliminate one problem at a time to make it easier on yourself. Then I'd make sure the KIPS is operating correctly, the E-s are known to eat the idler gears. Once those are squared away make sure you have no air leaks at the reed cage/carb boot, leakdown test as Goof suggested, and finally jetting.

Making a leakdown kit isn't too hard, probably the best guide I've seen is here: http://www.thumpertalk.com/topic/432226 ... -2-stroke/. It's a lot easier to do with the engine removed, but it can be done with it installed after you remove the carb and pipe.

You might remember the topic I had where my bike was pulling in water out the exhaust that turned out to be a crack in the cylinder under the KIPS cover. It is welded shut and holding water. The pump is fine, I installed new impeller bolt, seals/bearing. KIPS have a new left powervalve; all KIPS components lubed with high temp grease.

I'll look into the leak down thing

Ahhh, yes I remember that one. So they welded the cracks closed...if any of the weld intruded into the water jacket that could be contributing to the overheating as those passages aren't very big.

Possibly, but like I said only at higher cruising speeds at over 1/4 throttle in 5th is when it chokes out. I can bomb around the quarry with intermittent hard throttling for hours with no overheating or pinging. I'm certain it's a fuel delivery issue. Gonna wait and see if adjusting the float tang back to 16mm will fix it.

Yeah then that sounds like jetting. Probably if its not clogged partially the main jet is too small. Go through the jetting guide http://kdxrider.net/forums/viewtopic.php?f=105&t=1156 and you'll likley square it away.

bufftester wrote:You aren't suffering fuel starvation if you're pinging. And the overheating is probably leading to your pinging.

What do you mean here? You're saying running rich causes pinging? There is like a clacking from the piston and the motor quits right away when I stop. That's just after long straights with the bike on the road. Classic lean running overheating symptoms.

I don't think there's anything wrong with my jets. Air screw is 1 and 1/2 turns out. It runs great and can rev through the whole powerband in lower gears through the trails and stuff with no overheating. The problem only arises after a minute or two on the long straights when I got past 1/4 throttle at high speeds.

Did you ever get this figured out?

Yeeeah it was the float adjusted too low. I was trying to get the carb to stop leaking fuel by lowering the tang a few mm. Didn't work