KX experts chime in please

Aceofspades
Edited Date/Time 12/5/2015 5:42pm
I've noticed that anytime a manufacturer went from a single stage (fast maximum opening) main power valve to a dual stage (usually two piece main flapper that made the valve open progressively) valve, the horsepower usually went DOWN at the rpm of valve operation (6000-whatever rpms). This was true for the 97 rm250, and the 2000 kx250 which Ive owned.

This leads me to a question for possible experimentation: how would it effect my powerband to remove the secondary flap from my main kips valve so that it's a single stage main valve? I'm assuming a stronger hit, but in conjunction with delaying power valve opening by increasing governor pressure with a thick washer, would the hit be TOO much?

If no one has tried this I guess I'll have to be the guinea pig, but anyone with knowledge chime in.

Also: anyone goy a 1999 kx250 main valve actuator arm they'll sell me (the lever that lifts the main flapper) . Mine is a spring loaded deal that progressively opens the main flapper and I'd like an option. Thanks for reading my giant, autistic post lol Smile
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Aceofspades 12/4/2015 5:00pm
12/4/2015 5:00pm

the arrow is pointing at the 99 lever arm I'd like to try. The circled flap is how MY kx assembly Looks yet here is the actual 2000 assembly:





Aceofspades 12/4/2015 5:06pm
12/4/2015 5:06pm
In other words, I want to use the lever WITHOUT the spring assembly from the 99 to get a stronger hit but I'm worried that if I delay the hit with greater governor spring tension then the hit might be way too much. Also I'm wondering why my main valve Looks like the 99 assembly but my bike is a 2000? My kips governor has two springs like a 99 but the schematic shows only one spring in the 2000-02. I don't know what the frig is up with my bike ! Argh! Not to mention that I replaced my pc pipe with a stock 02 kx pipe and I STILL don't have much low end power! I'm thinking my power valve is opening way to soon for some reason.
Aceofspades 12/4/2015 6:04pm
12/4/2015 6:04pm

My 2000 has the small spring inside the big spring on the governor like the bottom illustratiom - which is listed as a 2001-2002 assembly. The spring seat is also the same as the 01-02. Weird.
Aceofspades 12/5/2015 5:42pm
12/5/2015 5:42pm
Quick follow up: I found 3 separate thickness washers and actually tried them in order. The thickest was nearly as thick as the washer next to the needle bearings. The second thickest delayed the kips opening quite a bit later, which completely changed the nature of the power delivery of course. The bike has a very nice, chunky low end that is seamless feeling. My first gear is still too tall, like all these model kx, but this washer mod really improved my situation a ton. The valve opens now in what I'd consider the beginning of the top end part of the power curve, and seems to be fully open a tad before the bike reaches its max revs. It'd be interesting to see how the pro circuit pipe would work with the bike now. I feel like if it has the lower 95 first gear that this bike would finally be a decent trail bike. It's weird that I never found the low end power that these bikes were supposedly renowned for, but for my purposes it's finally right about where I need it to be. I'd still like to try the 1999 main valve lever if anyone has a spare they'll sell.

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