KDXRIDER.NET

As the title says I have a '97 KDX200. I bought this last year and took it on a few runs at some local riding areas. Everything seemed to be running/working fine. Over the winter I replaced the reeds with 607 and put a moose reed spacer on. I figured this would lean out my slightly rich fuel mixture. Additionally my stock expansion chamber has some blow-by at the cylinder I can not seem to get it to seal, new crush washer, o-rings, and springs and still no seal. I figured this exhaust leak so close to the combustion chamber would create a lean condition also.

I currently have a lot of blow-by at the pipe and seemingly excessive spooge and a very boggy bike. Is it possible for the transmission oil to be sucked into the case creating overly rich or fat fuel to oil ratio? Otherwise I am back to pulling the carb back off and hunting down my jetting issue.

Any thoughts or suggestions? If offering jetting suggestions I am with stock pipe, airbox and snorkel still intact, 0-1500 feet, and about 60-90 degrees F.

Thanks in advance!

Keep an eye on your transmission oil lever or go ahead and do a vacuum / pressure test to check for a leaking right side crank seal.

I did a compression test today to find I'm right at the upper end of the servicable compression, 145psi. I let the bike sit for maybe 5 minutes to see if the compression would drop. It didn't even drop 1psi, at least not that I could see on the gage. It is using tranny oil. I thought if its sucking trans oil the compression would be either low or leak down.
I have a crank oil seal on the way. Am I going in the right direction?

Before the "C" test I ran it around the yard a bit so it was nice and warm. When I pulled the plug it was very oily and wet. That tells me the bike is sucking the extra oil from the trans side.

A wet oily plug tells you it's really rich. If your compression is holding then your seals are probably fine. Also your crank seals have to be put in by splitting the cases and removing the crank bearings...

If your crank seal was leaking at some point you would be getting a lean condition from air being introduced to the crank case.

How are you checking your oil level. Bike off or on?on a stand or the kick stand?

Obviously when its on its kick stand it will read low oil. When its on a stand or with me holding the bike level is when I check the sight glass. I'll fill the trans to the top of the sight glass. After a short ride its down between the marks on the sight glass.

Try putting one liter in it and see what happens. Mine I though was doing the same thing after I did a full rebuild and after I would do a heart cycle I thought I was losing oil but I waited about 30 min and the oil came back down and was at the full mark. How long are you waiting after you start it to check the oil

Another good way to tell is drain the oil into a bottle that has measuring units on it and see if there is oil missing

A compression test has absolutely nothing to do with crank seals or bearings.

For starters, without knowing exactly what jets are in the carb, or if the floats are adjusted correctly, you're just stabbing in the dark.
Verify the obvious first. It's free, and somewhat easy to do.

Must have figured it out....

I think we've found out that the clutch-side crank seal is leaking and sucking trans oil into the fuel mix.

Is there a way to replace the seal without splitting the cases on KDX H models? I have seen other brand bikes where the crank seals are done like this. Otherwise, my mechanic says $600 to split the cases and replace this seal.

KDX_Newbie wrote:Is there a way to replace the seal without splitting the cases on KDX H models? I have seen other brand bikes where the crank seals are done like this. Otherwise, my mechanic says $600 to split the cases and replace this seal.

Unfortunately not.

Is that $600 just to replace the seal or would he be replacing other items while the cases are split?

buy the tools and do it yourself. $600 is too much.

Tedh98 wrote:

KDX_Newbie wrote:Is there a way to replace the seal without splitting the cases on KDX H models? I have seen other brand bikes where the crank seals are done like this. Otherwise, my mechanic says $600 to split the cases and replace this seal.

Unfortunately not.

Is that $600 just to replace the seal or would he be replacing other items while the cases are split?

For $600 he ought to be replacing close to everything (top & bottom). Yikes!

Like Jaguar said, buy the tools and dig in. It's not rocket science and your be better for it.


Sent from my iPhone using Tapatalk

I took your guys' advise and decided to take on splitting the cases myself. Long story short, it is a pretty simple process.
Here are my findings so far. Crank seals on both sides were damaged and leaking. I also found earlier that my clutch basket was severly damaged by a stray chunk of metal debris. I found that two of my transmission teeth had broke off. Ouch! I see no other damage however. So add about $200 more to the cost of this rebuild.

Those new YZ250X are looking better every day. Maybe I'll sell the KDX when I'm all done and splurge on a new bike.