1991 KDX 250 Power valves do not always open

Kawasaki KDX 250

1991 KDX 250 Power valves do not always open

Postby Tinie » 11:46 am May 27 2018

I need some advice/help here.

This is now after the bike has been warmed upt thoroughly.
When I do accelerate it seems that the power valves do not always open up. The bike will make a dull noise and do not have high rev/speed power.
It is fine from idle to about half power. I can also hear that the power valves do not open. When they do open the bike has a lot more power and the exhaust note has a much higher pitch.
This happens about 50 % of the time. The power valves will then sometimes just open up suddenly but mot always. Then at the next run it seems fine again.

I then took off the exhaust/expansion pipe and also the plastic cover/boot at the linkage to the governer rod. I also took of the collar on the rod. While looking through the exhaust port, I the pulled this rod back and forth to make sure if it is loose or stuck. Everything seems fine and I can see that the side valves and the exhaust valve are opening and closing. Could it be that there is something wrong with the covernor lever/linkage to the governor rod?
Or what must I look for?
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Re: 1991 KDX 250 Power valves do not always open

Postby Jason » 06:33 pm May 27 2018

Is there any chance the rod is bent inside the tight side engine cover?
Thank you, Julien D for all your hard work!

PLEASE! Do not "dip" PWK Keihin carbs in Berryman's to clean them! It will damage the internal o-ring (jet block gasket).
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Re: 1991 KDX 250 Power valves do not always open

Postby Tinie » 11:15 pm May 27 2018

I do not think so.
What side or where is the tight side engine cover?
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Re: 1991 KDX 250 Power valves do not always open

Postby Jason » 12:24 am May 28 2018

Oops. RIGHT side, (inner clutch cover)

It sounds like a logical approach you are using. If you can see it all moving by hand, then it is not binding inside the cylinder. If you are seeing the gears open and close, the nall the teeth are not eaten off. Something may be wrong inside the engine cover.

Beyond that, any chance the subvalves are in backwards?
Thank you, Julien D for all your hard work!

PLEASE! Do not "dip" PWK Keihin carbs in Berryman's to clean them! It will damage the internal o-ring (jet block gasket).
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Re: 1991 KDX 250 Power valves do not always open

Postby Tinie » 08:29 am May 28 2018

No I checked and they are the correct way. Maybe something inside the cover is broken
Thank you for your help
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