1990 kdx200 top end issues

Discussion specific to the 1989 - 1994 (E Series) KDX200 model sold in the USA
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Ryan0190
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1990 kdx200 top end issues

Post by Ryan0190 »

Ok guys this is my second post on the site. As the title says I'm having top end problems. It seems to not gain an power after half throttle. I checked the compression and it's within spec. It has a dynoport pipe and silencer. There is a semi decent sized dent within the first few inches of the pipe. Could this cause it? Or do I need to clean the carb or power valves or what? Looking forward to your responses. Thank you
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Re: 1990 kdx200 top end issues

Post by ubareddition »

Check your reeds

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Re: 1990 kdx200 top end issues

Post by KDXGarage »

Start simple, then go towards complex.

Do check the power valve functionality.
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NV Rider
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Re: 1990 kdx200 top end issues

Post by NV Rider »

I had the same issue. A thorough carb dip and cleaning took care of it.


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Re: 1990 kdx200 top end issues

Post by 6 Riders »

Do NOT "dip" your carb......It is OK to do a thorough cleaning, including replacing the jets and following the jetting guide.
You don't say what bike you have, so, there may, or may not be issues with it.
newbbewb wrote:^what he said.
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*side note...I'm drunk, so try to read what I'm trying to say, instead of what I actually type
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Re: 1990 kdx200 top end issues

Post by KDXGarage »

NV Rider wrote:I had the same issue. A thorough carb dip and cleaning took care of it.


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Carb dipping is a no-no with the usual harsh solvents on 1988+ KDX full sized bikes. They have a Keihin (KAY-heen) PWK, which has a jet blaock gasket that harsh solvents can attack.

6 riders, he has a 1981 KDX250 with a Mikuni. I would guess VM series?
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Re: 1990 kdx200 top end issues

Post by NV Rider »

Good point, Jason.


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Ryan0190
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Re: 1990 kdx200 top end issues

Post by Ryan0190 »

Well guys the motor is getting taken out today to split the case and replace the kickstarter spring (takes about 20 tries to get a good kick). So I'll check the carb and reeds and the kips. Thanks for the help. Any little tidbits of info that would help me would be much appreciated
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Re: 1990 kdx200 top end issues

Post by KDXGarage »

Just want to be sure, no need to pull motor and split cases for just the kickstarter spring. Is it two sepaarate repairs?
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Re: 1990 kdx200 top end issues

Post by ubareddition »

Left hand threads on kips arm actuator

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Re: 1990 kdx200 top end issues

Post by bufftester »

Exactly, if its just a kickstarter repair leave the motor in, drain the oil and just pull the right side engine cover. Only time you need to split cases on these motors is to replace crank bearings or repair the transmission, mot everything else can be done with the engine in the bike.
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Re: 1990 kdx200 top end issues

Post by Ryan0190 »

What about to clean the power valves? Don't really think I can get to them with out taking it out
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Re: 1990 kdx200 top end issues

Post by KDXGarage »

You take the cylinder off, but not split the cases or remove frame from engine.
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Re: 1990 kdx200 top end issues

Post by Ryan0190 »

Ok I replaced my ratchet spring today. And was playing with the powervalvery actuator/arm and I guess Ithe must have been gummed up because the bike seems to have alot more power now. It's still takes like 20 kicks to start it though. Sprayed some starting fluid ii it after the like 15th kick and it started right up. Any ideas as to the issue? Also, I messed up my clutch cover seal/gasket and leaked all my transmission fluid out. So I ran down to napa and picked up some blue rtv and use that to seal it up. Will this hold up?
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Re: 1990 kdx200 top end issues

Post by KDXGarage »

I doubt GOOP will do.

Have you checked the reeds?? Which spark plug are you using? New, recent?
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