Bog at the top of powerband WOT

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kdx_jeeves
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Bog at the top of powerband WOT

Post by kdx_jeeves »

Hey fellow KDX'ers,
I have a 1990 KDX 200 that I've been enjoying the hell out of for the last year.
It's maintenance time, and I have an issue I'm about to dive in to.

The last time I went riding, the bike did not want to start. By not want to start I had to kick it about 8 times. Typically it starts cold on the first or second kick.

Once I got it going, I noticed that I had no power at the top of the power band.
Imagine being in second gear and trying to bring the front end up. Powerband hits then bogs once you get to the top of it (in any gear).
I messed around with this for a bit, at one point I held the throttle wide open down a long stretch and it just bogged along.
The bike is responsive in all areas except the mid to top range of the powerband.
After 20 mins of this I decided it was toast, and on the way back to the house things slowly started responding better. I was able to get the front end up normally once I got back to my house.

I have other issues that may be contributing, but I wanted opinions on whether anyone has had the behavior above.

My carb also leaks gas from the overflow when sitting off, and I'm going to be taking it apart for the first time to inspect the float.
The petcock also doesn't work and allows gas to flow to carb regardless of the setting, which is why I'm 99% sure my float isn't working as it should.

Just not sure if a bad float would contribute to the response problem above.
Thanks!
bultaco4ever
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Re: Bog at the top of powerband WOT

Post by bultaco4ever »

You want to eliminate the overflow leak anyways, so, fix that first. Then see how it performs.
Chilly
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Re: Bog at the top of powerband WOT

Post by Chilly »

If the gas leak ain't your problem then it Could be a broken power valve part, or the crank seals are leaking. Open the stator cover and see if you see oil.
sarrant
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Bog at the top of powerband WOT

Post by sarrant »

E series that falls flat on top? Generally, bad KIPS subvalves. They are prone to failure

Your hard starting seems like a typical result for a bike with a leaky float/petcock like yours
newbbewb
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Re: Bog at the top of powerband WOT

Post by newbbewb »

Bad power valves kill bottom end in my experience. Will still run good on top end
93 kdx200-Highly modified
89 kx125/kdx200E engine
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ohgood
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Bog at the top of powerband WOT

Post by ohgood »

kdx_jeeves wrote:Hey fellow KDX'ers,
I have a 1990 KDX 200 that I've been enjoying the hell out of for the last year.
It's maintenance time, and I have an issue I'm about to dive in to.

The last time I went riding, the bike did not want to start. By not want to start I had to kick it about 8 times. Typically it starts cold on the first or second kick.

Once I got it going, I noticed that I had no power at the top of the power band.
Imagine being in second gear and trying to bring the front end up. Powerband hits then bogs once you get to the top of it (in any gear).
I messed around with this for a bit, at one point I held the throttle wide open down a long stretch and it just bogged along.
The bike is responsive in all areas except the mid to top range of the powerband.
After 20 mins of this I decided it was toast, and on the way back to the house things slowly started responding better. I was able to get the front end up normally once I got back to my house.

I have other issues that may be contributing, but I wanted opinions on whether anyone has had the behavior above.

My carb also leaks gas from the overflow when sitting off, and I'm going to be taking it apart for the first time to inspect the float.
The petcock also doesn't work and allows gas to flow to carb regardless of the setting, which is why I'm 99% sure my float isn't working as it should.

Just not sure if a bad float would contribute to the response problem above.
Thanks!
fix the float needle problem, and the petcock. then ride it again.
CAL-kawi
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Bog at the top of powerband WOT

Post by CAL-kawi »

If your power valve was stuck closed you'd lose top end power, but sounds like you have more of a bog? I'd fix your float issue first, and then check your main jet for any blockage.
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