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Right Side Crank Seal Question..

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Do crank seals sometimes start leaking slowly? Or do they just go all at once and start putting out clouds of smoke?

Reason I'm wondering, KDX fouled a plug again today. It's also started spooging like crazy in the last 3-4 rides. But it's not smoking any more than normal that I can tell. It's jetted 40/150 with a CEL needle in the second notch. I've been in the carb a few times lately dealing with the clogged pilot jet problem that was solved with an inline fuel filter. Checked the float level, but didn't change it. Only carb changes I've made lately was putting the airbox lid back on (minus the snorkel), going from a 152 main to a 150, and adding the CEL needle. But all this (except the airbox lid) was after it fouled the first plug (which I thought might be a fluke, but apparently not).

So, on the surface, nothing in the carb area sounds to be at fault. That leaves me wondering about a very slightly leaking crank seal adding a small amount of extra oil, enough to cause some pretty serious spooging and fouled plugs every 50-60 miles or so.

Bike starts and runs great otherwise.

Thoughts on this, and any other ideas..

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Is the tranny oil disappearing?

If so then the clutch side crank-seal is leaking, I owned several Yamaha IT's over the years and almost all of them leaked. Then again, I bought them used and they had some hours on them, the most notorious is the IT200 the motor Yamaha used on the Blaster.

Once you replaced it, everything was perfect, that was a nice Enduro motor in the IT.

I owned a KDX220R and it was a torquey bigtime, I liked it but I did not ride it that much and sold it.

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If it is, it's going very slowly. I put 800ml in it last time I changed it, so it may take a little while to actually start dropping in the sight glass and be noticeable. I'll be watching it though.:thumbsup:

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Also, your transmisison oil will smell like pre-mix after a while. Crank seals usually leak both ways when bad.

In my experience the LH seal seems to go bad more easily. Presumably the weight of the flywheel and fatigue on the LH crank beraring.

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Kinda hard to think that the seals would be going bad with as few hours as the bike has on it anyway. It still has the OEM piston in it and plenty of compression.

It has always spooged a bit, and the plug is always coal black no matter how I jet it, but lately the spooge quantity has went way up and fouling plugs is a totally new thing. It never did that even with the stock jetting.

So I'm in head scratching mode. I'll wait a bit and watch the transmission oil level.

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A leak down test should tell you, if you are equipped to do one.

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I've thought about that. I'll find the threads about stuff required to do the test. I can make everything needed for it, just gotta re-find what's needed and how to go about it.

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whens the last time you packed youre silencer.you said you had alittle spooge so it could be soaked in oil.

just a thought.

Kawie

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higher temps = too rich jetting

if it gets even worse on hotter days, that could be why

Actually it seems to be getting worse as it warms up. But it's just now getting into the low 80's here at 1200-1300ft, and at 40/150, I'm about scared to go any leaner.

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to check to see if your crank seal is bad, pull your spark plug out and slowly crank the motor over with the kickstart with your hand and carefully listen for the compression leak since two strokes have compression in the top and bottom end. if you feel the compression going away when you slowly spin the engine then you have one or more bad seals.

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Kinda hard to think that the seals would be going bad with as few hours as the bike has on it anyway. It still has the OEM piston in it and plenty of compression.

It has always spooged a bit, and the plug is always coal black no matter how I jet it, but lately the spooge quantity has went way up and fouling plugs is a totally new thing. It never did that even with the stock jetting.

So I'm in head scratching mode. I'll wait a bit and watch the transmission oil level.

No matter how you cut it, the bike is an 04 with 7 y/o seals, etc.

A leak down test should tell you, if you are equipped to do one.

That's what I'd do followed up by a top end. There's a nice thread on this in our FAQ.

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