Leak down test

Discussion specific to the 1989 - 1994 (E Series) KDX200 model sold in the USA
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90SDKDX
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Leak down test

Post by 90SDKDX »

Hello everyone. So I've been fighting my 1990 KDX200 for some time now. I had a weird stall out that happened last summer and could never get the bike running again. Got it running again this summer, however, when going WOT for too long the bike starts to stall out and sputter until you roll back off the throttle.

I've went down several sizes on my main and have gotten no where.

I finally have gotten around to doing a leak down test. After getting the engine sealed up I can pump and pump and pump and never get it to hold pressure. If I pump fast enough I can get it up to about 4 psi or so but the needle drops quickly.

I've sprayed soapy water all around the exhaust plug and intake to make sure there's nothing going on there. Removed the magneto to get to the left side crank seal, no leak there. Tried listening for a leak from the transmission side and didn't see/hear anything. Sprayed the base gasket, head gasket, spark plug, nothing. The only area I've found any bubbles is coming from the seal on the right side of the kips shaft.

Part # 92049 is the seal in question. It doesn't even look like a seal, almost looks and sounds like metal. Maybe it's just super hard.
What effect if any would this have on jetting? And would it have that great of an affect on my leak down test? I would think it would be a slow leak if anything. Perhaps I have the piston in the wrong position?

I do know the tester works as I used it on my RD350 with zero issues. I'm about at my wits end with this bike.


https://www.kawasaki.com/Parts/PartsDia ... /KDX200-E2
John_S
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Re: Leak down test

Post by John_S »

I remember reading about the stalling and erratic starting issues. You were thinking at the time you needed to tear down the engine. What ended up fixing that problem?

If you know that your tester isn't leaking and the engine won't hold any pressure then you don't have many options other than a top and bottom end reseal.
90SDKDX
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Re: Leak down test

Post by 90SDKDX »

John_S wrote:I remember reading about the stalling and erratic starting issues. You were thinking at the time you needed to tear down the engine. What ended up fixing that problem?

If you know that your tester isn't leaking and the engine won't hold any pressure then you don't have many options other than a top and bottom end reseal.
I honestly have no idea what fixed the problem. I put a new electrosport stator in, tried my aftermarket cdi, nothing. Put all the original electrics back on and it magically started.

The thing with the test that's driving me crazy is the bike runs! If the seals were leaking this bad, you would think it would never even attempt to start. Maybe all the seals behind the clutch cover are bad, and when full of transmission oil seal up enough to run. The tranny oil doesn't seem to be going down though. Idk.
John_S
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Re: Leak down test

Post by John_S »

I would double check the tester even though you used it with good results on another bike. Maybe it's the pump itself leaking. What are you using to pump it? The original blood pressure bulb I had on my tester started leaking and it was tough to figure out until I put the whole tester under water and saw the bubbles. Try to plug the end of the tester and make sure it holds 6psi for 6 minutes or squeeze the end as hard as you can against your palm (hurts like hell), pump it up and dunk it underwater. I ended up buying a rubber cap and hose clamp so I can test it in the future.

Make sure the piston is at the bottom of the stroke for the leak down. It has to be below the transfer ports or it's not pressurizing the head gasket and spark plug.

Check the engine compression.

I also don't think it would start if it had that bad of a leak.
kdxdazz
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Re: Leak down test

Post by kdxdazz »

you are right about that seal,i had the same thing with mine and it made the leak down test impossible, i was unable to find that seal(its actually called packing) so when i did an engine rebuild i had to reuse the old one,as to what affect on jetting that has i don't know but all i can say is my bike is still not running well
1999 KDX220SR (KDX220-B5)
90SDKDX
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Re: Leak down test

Post by 90SDKDX »

kdxdazz wrote:you are right about that seal,i had the same thing with mine and it made the leak down test impossible, i was unable to find that seal(its actually called packing) so when i did an engine rebuild i had to reuse the old one,as to what affect on jetting that has i don't know but all i can say is my bike is still not running well
According to the parts fiche, it's an oil seal. Doing a google image search shows it as an oil seal and it is available. What year is your kdx?
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