1985 K100RS Valve Clearance Check and Possible Adjustment

[brian thompson]

I am planning to do a valve clearance check and adjustment (if necessary) on my 85 k100rs and I have a number of questions.
Further Background : the bike has about 85k on it

This one is kind of a "just curious" kind of a question.
What can happen if the valve clearance is out of adjustment?
as in: what if I did nothing and drove it another 20K?

The checking part of the job seems simple enough (if clymer is to be believed) and the adjustment also seems simple enough.

There are however special tools 11-1-720 (decompressor lever) and 11-1-722 (valve lifter holder) that the manual.

Has anyone used these items and what are the ballpark costs on them?

Has anyone used a more or less off the shelf general use over bucket or under bucket shim tools available from an automotive store? - Did it work? or did you go back to the BMW tools?

any hints or tips you can recommend?
stuff you learned the hard (or expensive) way?

thanks for the input

[jpeck]

I purchased a set of valve adjustment tools for 2 valve k bikes for around $25 which are a little crude but work fine. look under tools for sale on the ibmwr site

http://www.ibmwr.org/market/adlist.php?cat=tls

[deilenberger]

Not knowing what Joan Jett would do, I'll reply to:

Originally posted by brian thompson
I am planning to do a valve clearance check and adjustment (if necessary) on my 85 k100rs and I have a number of questions.
Further Background : the bike has about 85k on it

This one is kind of a "just curious" kind of a question.
What can happen if the valve clearance is out of adjustment?
as in: what if I did nothing and drove it another 20K?


Bad things. If the valve clearance starts to close up, you'll start by loosing power. If they close up enough, you have a possibility of burning the valve. If the clearance starts to open up (unlikely), you'll basically loose power, and accelerate wear on the valve components.


The checking part of the job seems simple enough (if clymer is to be believed) and the adjustment also seems simple enough.

There are however special tools 11-1-720 (decompressor lever) and 11-1-722 (valve lifter holder) that the manual.

Has anyone used these items and what are the ballpark costs on them?


I always use them for adjusting the valves, although luckily, adjusting is actually rarely needed. Trying to do it without these tools stands a chance of damaging a camshaft... which will be lots more expensive than the tools. There are actually three tools, one to depress the valve, one to hold it depressed while swapping out the shim, and one like a little bent screwdriver to pop the shim free from the cam follower. The last tool isn't vital, you could use a dental pick, or a magnetic pickup tool to get the shim out.


Has anyone used a more or less off the shelf general use over bucket or under bucket shim tools available from an automotive store? - Did it work? or did you go back to the BMW tools?

I bought a set of the factory tools off the IBMWR marketplace years ago for about $50 - all three tools. Then I lucked in at a flea market and our local club bought a complete BMW shim kit for $40 (quite a deal.. for that price.)

Nope. I believe someone posted that ones for the early water cooled VW engines are very similar in design and people have used them successfully. I haven't so I wouldn't recommend it.


any hints or tips you can recommend?
stuff you learned the hard (or expensive) way?

Sure. Buy the valve cover gasket set before you do the job, and replacements for the rubber donuts on the valve cover bolts.

The donuts are what actually hold the cover to the head - the bolts are special shoulder bolts that should NOT be tightened very tight... the rubber donut does the holding.

If you've never replaced these - it's time, and if you don't know if they've ever been replaced - it's good insurance.

Also get some RTV sealant or Yamabond for the 1/2 moons at the rear of the head and the corners of the gaskets.


thanks for the input

No problem.