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Bike sat for a year or so. When I cranked it up it went straight to high rpms. I cleaned the carb. Figured my idle circuit was lean. Didn’t fix it. Cleaned the carb again. Same issue. Just did a pressure test, Put 7 psi on the motor. It held the pressure. So I don’t have an air leak. Getting desperate here guys. Any suggestions would be greatly appreciated.

timing off somehow??

Have you tried a different plug??

I had the same problem on an old '84 CR250 I used to own. The weird thing was, the kill switch would not shut off the bike when the RPMs went way up. Turned out the base gasket was installed incorrectly (not by me ) and there was a vacuum leak. I'd check for vacuum/air leaks.

Yes. That is true. In addition to a pressure test, do a vacuum test.

Jim B, awesome finger wag, HECK YEAH!

Jason wrote:Jim B, awesome finger wag, HECK YEAH!

I bought that old CR to part out and decided to fix it up and ride it. (I bought the CR not long before I bought the KDX. Once I bought the KDX I lost interest in the Honda and did wind up parting it.) It was a bit ratty, but it was REALLY fast. It was ported and had no low end to speak of (pre-power valve) but, boy, did it have a mid- and top-end hit.

HA HA

Power valves are nice!

OK, I'll try a vacuum test tonight and post the results. Thanks Guys.

chriswelfare wrote:OK, I'll try a vacuum test tonight and post the results. Thanks Guys.

Have you tried spraying carb cleaner to check for vacuum leaks? Be careful if you do it. (I'd only try it on a cold engine.)

Jim B I have tried the ol carb cleaner trick. Tried it with starter fluid too. No results. I've got a spare carb I'm gonna try on the bike tonight off my donor bike. I've sprayed cleaner through all the jets and disassembled everything but i guess there is a chance that a passage way is plugged somewhere. http://www.kdxrider.net/forums/viewtopi ... 77&t=22279#

chriswelfare wrote:I've sprayed cleaner through all the jets and disassembled everything but i guess there is a chance that a passage way is plugged somewhere. http://www.kdxrider.net/forums/viewtopi ... 77&t=22279#

I meant to spray it on the outside of the engine (say, around the base gasket) to see if it affects the RPMs while the engine is running.

Exactly. I got the bike started and sprayed carb cleaner all over the motor, carb boot and carb. No results so I tried the same trick with ether. Still no results. All signs point to a leak but I just cant find one. Gonna put vacuum on it tonight.

chriswelfare wrote:I got the bike started and sprayed carb cleaner all over the motor, carb boot and carb. No result...

Weird.

I know. I'm gonna try vacuum tonight to completely rule out a leak. Then I'll try the spare carb. I didn't run it for nearly a year. I think there is something in a passage in the carb somewhere. I cleaned the jets and tried to blow out all the passages. I've got both carbs soaking right now. I'm gonna beat this tonight.

chriswelfare wrote:I've got both carbs soaking right now.

Be careful not to ruin the jet block gaskets.

Ummm, what are "Jet Blocks"?

Ok, a little googling and I answered my own question. I haven't dissembled the jet block so i'm not sure how I would damage the gasket. Am I missing something here.

Try the search. It's a very common problem with the PWK. The jet block is the part where the main jet mounts. It's sealed to the carb body with a gasket that tends to go bad over time. Especially if the carb body has been soaked in carb dip.

chriswelfare wrote:I haven't dissembled the jet block so i'm not sure how I would damage the gasket. Am I missing something here.

They deteriorate over time and carb dip is pretty bad for them.

Ahhh, Ok, thanks for the info. Good to know.

One really should not dip a PWK carb.

Sudco or jets r us for a new gasket, Security Torx 10 or 20?? to get the jet block out and replace the gasket.

If it sets up for a year, then the carb needs to be cleaned, lawn mower, motorcycle, leaf blower, weed trimmer, whatever.

Try not to use ethanol in any of those and try not to let them set up.