Oily XR Rocker Box

Joined
Aug 24, 2001
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#1
Actually my bike is an XLR 250, 1992. This is a Japanese import, basically a detuned XR
250.

I need help on two items:

There was an oil weep from the left front cylinder-barrel joint. Took off rocker box and
the left front valve "well" was swimming in oil, flush to the level of the rocker box joint.
The right well drains into the cam chain tunnel and was "dry". I would have thought the
left front well would have drainage flows cast into the head. It seems not. This explains
the leak/weep at the cylinder head directly under this valve well. It explains why one
port of the exhaust, adjacent to the left well, is black and oiler than the right ( cam
chain side)

My question is: Is this oil buildup normal on XR 250's? If not, why and what remedies?

My second problem is the cam chain. How can you tell if it is worn when still on the
bike? Should you be able to lift it AT ALL clear of the teeth of the cam-sprocket? Can
you test it for looseness in place? If so, how. I am getting a weird slapping-pinging noise
at about 25% revs when the bike is pulling (opened up off the cam, so to speak) hard.
It sounds like its from under the fuel tank.

Thanks for help. I am hundreds of miles from a dealer.

email: pamoja1@wananchi.com

Cheers

Peter in Africa
 
Joined
Aug 5, 2001
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#2
Hello,
As for the oily rocker box, I'm not real familiar with the XR valve train. However, with your description of the noisy cam chain/valves, it sounds like your valves are way out of adjustment. This might also be the reason there is too much oil up there. My '87 XR200 has a rubber boot covering two nuts, one is a lock nut. It is located on the left side of the bike, behind the cylinder head, on the top of your cases, and right below your carb. This is an automatic cam chain tensioner. Loosen the lock nut on top slightly, while the bike is running, and it should tighten your cam chain (assuming your '92 250 has one of these). Either way, it sounds as if you might need a whole new chain, if it has stretched significantly, tightening won't help it much. The valves can be adjusted under the big hex head caps on the top of the cylinder head. Of course, if you try to adjust your valves, you will need to find specs for your intake and exhaust clearances, and always do valves with a cold engine. Do some research on adjusting valves for your bike, and/or order a Honda Service Manual. I wish I could help you more. Good luck.
 
Joined
Aug 22, 2000
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#3
A few questions prior to an answer:

One, is this an RFVC engine?

Two, was the engine smoking before you tore into it? If so, how often? Just at startup, or all the time?
 
Joined
Aug 24, 2001
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#4
Oily etc

Yes, it's am RFVC, 99% identical to an XR 250.

It is hardly smoking. It is only rich and a little oily in the left exhaust port. It is rather leaking/weeping oil at places noted, due to oil build up in the left front valve well/seat spring area. I am surprised there are no channels in the left front vale well of the cyl head to drain oil back.the job done by the cam chain hole on the right side.
 
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#5
It is only rich and a little oily in the left exhaust port.
It's got to be oil. A rich condition would cause soot buildup in both exhaust ports, not one.

Do you run a synthetic oil? If so, smoke may not be visible (but you'll still be able to smell it!).

I'm trying to determine if you'll need to install a new valve guide, or just a seal.

The drainage issue is something I'll deal with on Monday - I need to ask my boss a question before I can give you a complete answer. Sorry for the stalling technique!