kx250 power problem?or design?

[conkx95]

recently got myself a 2001 kx250 with a lot of work done to the engine (new top end,crank,cylinder head) and various other stuff.the bike is amazing condition also but it does not seem to have that pull your arms off power in the top end as other 250 2 stroke! if owned a cr250 and a yz250 which when you hit that power and they pulled like a train! this bike has an enormous amount of low to mid range but when you hit the power and it revs out beautiful and crisp exactly how it should sound but just dosent seem to quite have that kick (I mean it still pulls it's by no means "weak") but im just wondering just the gearing Kawasaki gave this particular year? are all 2001 kx250s just lacking ever so slightly in the top end power???

any insight would be greatly appreciated!!
running FMF gnarly header and end turbine core 2 silencer with 13/48 gearing

 

[truespode]

Is there a flywheel weight on it?

 

[Okiewan]

Ported?

 

[conkx95]

Is there a flywheel weight on it?

no no flywheel weight

 

[conkx95]

Ported?

no porting done, Its strange the bike runs great and the jetting maybe needs a small tweek but nothing major, it idles perfectly too

 

[Okiewan]

Humm... maybe the problem lies between your ears? How long ago did you own the other 250's ? Sounds like the bike runs well, maybe your memories of top-end are a little exaggerated?

 

[conkx95]

Humm... maybe the problem lies between your ears? How long ago did you own the other 250's ? Sounds like the bike runs well, maybe your memories of top-end are a little exaggerated?

haha the problem could very well be between my ears there was a year gap between the last bike and this one, but I have a friend with a yz250 who I was out riding with the other day and I had I had a spin and there was a a definite stronger pull in the powerband..maybe the 01 kx is just built to have a very broad power delivery and not as much on top

 

[Ganggreen]

I'd pull the cylinder and check the KIPS Valves. I've seen them bound up, or even the drive gear froze, heck could be as simple as the little KIPS control arm slipped off

. My 1999 KX ran like a KDX when they were stuck.

 

[Okiewan]

Thanks for that GangGreen! If I were a betting man, I'd wager you that you nailed it. (If of course it actually is down on power) .

My 99' KX250 wasn't stock very long, but I can tell you it had a somewhat mellow hit, but by no means felt weak on top. Soon it was off to Eric Gorr for a 310 kit and porting. Then it pulled like a tractor from bottom to top!

 

[Ganggreen]

Thanks for that GangGreen! If I were a betting man, I'd wager you that you nailed it.

It could be as simple as the KIPS valves aren't properly aligned. It's not hard, but kind of tricky to reassemble. Pull the pipe, take off the KIPS plastic cover, move the KIPS lever in and out, look up in the cylinder. He should se the KIPS valves move in and out.