The Background: My buddy bought the bike (09 KLX 250s) new. From day one it didn't start well. 7000 miles later he ran it out of oil and the motor seized. I helped him yank the motor out to take to a shop. The motor rolled around in the trunk of his car, and the carb and rest of the bike were exposed to the elements for two years. My buddy gets a new job in another city and decides he's done with the bike. He gives it to me because he doesn't know what else to do with this mess.

What I've done to the bike
BB351 kit
Web Cams 101 grind
DynoJet Stage 2 kit
Lid removal
Block-off plate and KCS removal
Stock Pipe
New Head and Valve work done by local trustworthy shop
Cleaned out everything else
Put it all back together and only had 3 leftover screws haha

What happened after assembly:
It started up pretty easily but idle was all over the place
I let it get to operating temps keeping it below 4000 RPM
Shut off and cool down, everything seems kosher

So it sounds like it should be a pretty rip-snorting little badash, right? Well, heres is what happened next:

I took it for a ride around the block and it is just... well, really slow.. I thought as break in progressed it might improve, but I've put a few hours and 30 miles on it now waiting for some punch to show up. Nope, nothing. How slow you ask? it won't even rev over 7000 rpm when I ride it
Also, Idle is still all over the place. It may be anywhere from 3000 rpm down to getting below 1000 and dying.

So what do you think guys? Carburator? Vacuum leak? Rag left in a pipe? Fire away with any questions, suggestions or experience that might help. Thanks!

 

It could be a jetting issue. What's your setup? You may want to check out this thread on jetting setups.

https://www.kawasakiforums.com/forum...adsheet-39762/

 

Whats the jetting?

 

DJ 124
needle in 3rd position as per instructions

 

Sounds lean due to air leak or faulty carb. I would teardown carb, clean, inspect, and reinstall. Maybe the slide spring is too weak allowing slide to open too much.

 

With all you did, it sounds like you returned it to "brand new" condition... complete with that fresh out-of-the-box lack of power! LOL

Can you tell us more - like "Is it gutless up to 7000 RPM, or plenty of power, just won't go above 7000?" What does the exhaust look like (black?) Plug looks good, or sooty?

If I wre to guess, I'd say rich, vs. lean... but looking at the exhaust and plugs would better confirm that.

 

HA! exactly!

It is gutless up to 7000 rpm and won't rev any higher. I haven't tried revving any higher without any load. I'm only 15 miles into break-in.

 

I completely tore down and cleaned the carb as part of the rebuild and putting in the Dynojet kit (which included a new slide spring). I was actually thinking the slide sticking down as a possible cause though. What brings the slide up anyway?

 

Vacuum.

With the bike running spray some carb cleaner around the intake boot and carb. if the RPM increase then you have an air leak. Did you remove some of the smog stuff? If you did make sure there is no air leak there also.

 

Run it with the intake boot off and see if the slide is lifting when you open the throttle.

You cleaned it, but maybe not good enough?