Bad Crank Seals

Red_Rooster · Post by **Red_Rooster** » 02:13 am Oct 10 2006

Im not gonna recap the whole entire history of what problems Ive had. Leave it that I suspected bad crank seals to be the cause of my jetting and carb issues. So, I pulled the flywheel and stator, and here is what I found:

So..Is it time to split the cases and replace the seals???

Also look here for more pics and info:

http://snozberrybeads.com/kdx/

m0rie · Post by **m0rie** » 08:52 am Oct 10 2006

Sure looks to me like that seal is leaking. If your going to tear it down and replace the seals completely go thru the bottom end and check/replace the crank and all seals that require the cases to be split.

chris_psmith · Post by **chris_psmith** » 02:06 pm Oct 10 2006

Looks like case split time, don't make the same mistake as me and put the output shaft seal in the crankshaft seal hole, they have the same od, a real pain!

Post by **fuzzy** » 02:16 pm Oct 10 2006

Oh yeah! That'll get lean on ya!

canyncarvr · Post by **canyncarvr** » 02:56 pm Oct 10 2006

It's the tranny oil-top-off part that is the absolute 'fer sure indicator.

That and your sparky plug. It's ugly!

Is this a do-it-yourself project?

**the edit disappeared**

It's the RH side that gets you oil generally. The LH side gets you air. I believe that is true for the KDX.

Seals fail because bearings fail. Bearings fail (when properly installed) due to lack of lubrication.

Any pause on the 50:1?

Red_Rooster · Post by **Red_Rooster** » 03:53 pm Oct 10 2006

Yes, it is a do-it-myself project..Ive done it before on other bikes. I am the 2nd owner, for only a year, and the previous owner ran 50:1, since 1996 when the bike was new. I dont know how much use it got, it had its first topend prior to me buying it this time last year. Ive read many posts about ratios, and it seems pretty common to run at this ratio. Now, I have ridden and raced the pi$$ outta this bike in the last year...Maybe I just burned it up. Afterall it is 10 yrs old...

Any tips or tricks particular to this motor I should know about before I pull it and split it? I figure Ill do crank bearings & seals, rings, maybe send the head and carb off to RB for a little work, as well as all of the other seals..so much for riding for a while...and we are just entering into the Arizona Riding Season....

canyncarvr · Post by **canyncarvr** » 04:31 pm Oct 10 2006

No tips or tricks from me.

I haven't split cases on the KDX. To be more exact, haven't ever on anything.

I do wonder about things like splitters...some say 'You must' some say, 'I use a gear puller, some 2x4s and a hammer.' I've read plenty of horror stories about setting seals too deep in the case, not deep enough..all sorts of traps just waiting.

Last I checked, FRP charged $150 just to split the thing. That tells me it isn't a piece of cake.

But...everything is easy if you know how to do it. I remember a time I had trouble changing an intake manifold on a V8. Didn't take the alignment pins out of the block!!

Heck..time was I couldn't wrap my head around a 4-speed synchromesh transmission. WHAT are all those things spinning around in there at different speeds at the same time on the same shaft DOing!!??

That was a few engines and transmissions ago. Looking back..I wonder how I could'a been so stoopid.

It does make me laugh at some youngsters these days and what they think they know.

Ha! Been there!

Good luck.

If you end up with a list of pointers and/or tricks yourself for the KDX, I'd sure like to read about it.

Now then...about truing a crank by banging on it with a hammer.....

Post by **Indawoods** » 08:37 pm Oct 10 2006

The Online KDX manual has step by step instructions for doing the case splitting if anyone is interested.

It say use a case splitter, it is the only safe way to split the cases.

It also says that leaving the petcock in the on position during storage is a cause for seal and bearing damage. The fuel will leak down over time.

canyncarvr · Post by **canyncarvr** » 09:47 pm Oct 10 2006

That petcock is a bugger. 9:00 may be off, but 8:58 and/or 9:02 isn't! For those of you that store their rides for any length of time, I'd suppose that draining the tank or physically blocking the fuel line would be a good idea.

Red_Rooster · Post by **Red_Rooster** » 01:31 am Oct 11 2006

Indawoods wrote:The Online KDX manual has step by step instructions for doing the case splitting if anyone is interested.

It say use a case splitter, it is the only safe way to split the cases.

It also says that leaving the petcock in the on position during storage is a cause for seal and bearing damage. The fuel will leak down over time.

Where can I find the Online KDX Manual??

m0rie · Post by **m0rie** » 02:05 am Oct 11 2006

Top right corner of the page.

chris_psmith · Post by **chris_psmith** » 05:11 am Oct 14 2006

Posted my experience of case split under heading : transmission output shaft stripped , it wasn't too difficult.
Regards
chris

Red_Rooster · Post by **Red_Rooster** » 04:22 pm Oct 16 2006

Thanks all, I got the cases split and I have the crank being rebuilt with a Hotrods crank. I had 3 different shops measure my bore and all three confirm that the bore is still within stock limits, nowhere nearing the service limit for the bore. the piston, though in really good shape (less than a year on top end job) is close to the service limit. Im gonna go ahead and put a piston in it. After reading the many many posts on the subject, I am going to put a Wiseco piston in it, as I can get a really good price on one through a member of the riding club I am a member of. My Cylinder is a "B" cylinder. I always let my bike warm up for at least 5 minutes before hitting the trails.

On a side note, it doesnt look like the KIPS valve had ever been cleaned, even when the previous owners did the top end. It was so gummed up, that the pin that rides in the centrifigul actuator was bent. fortunately, the valves, and everything were in great shape.After many hours with the solvent tank, and oven cleaner everything is clean, and reassembled in the cylinder.

I was a little frightened of getting the timing right, but now that I understand how it works, and can see all of the dots, dimples and lines on all of the parts, reassembly was pretty much straight forward. Again, thanks to everyone on the board. Ill keep everyone posted on the rebuild progress.

Post by **fuzzy** » 01:29 pm Oct 17 2006

I have the crank being rebuilt with a Hotrods crank.

Too bad they don't make a stroker/cyl spacer plate combo! I can only imagine how a 200cc KDX stroked to something like 215cc would lug!

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Bad Crank Seals

Bad Crank Seals