Valve Clearances

I have a 1982 XJ650 Maxim.

Two questions.

Are the clearances for all valves supposed to be between .006 and .008" ?

When fitting new shims do you shoot for the maximum clearance of .008" or for the midpoint of .007"?

 

Hi, I've looked in my service manual and you're right all the valves clearances should be between 0.006 and 0.008in for all the 650 models.

I'm not sure about the second question, personally I would see what clearance the shims you're taking out are and look at the chart in the manual, it can be anything between the two according to this. I think it would be best to go for the smallest clearance, as theoretically the clearance would stay within the limits for longer and not require another adjustment as soon. Maybe someone else on here could confirm or counter this?

 

The clearances become tighter with wear. All of my out-of-spec clearances are tighter than spec.

The question is do you go for .008 that would allow maximum miles before the shims need replaced again or do you go for the midrange .007?

 

I'll counter it.
As the valve train components wear, the tolerance gets tighter, so to get the most out of your efforts, go with the larger end.
Too much clearance creates noise
Too little clearance and you risk burning and warping exhaust valves.

 

Thanks TIMEtoRIDE. I will go for the shims on each valve that get me closest to .008 but still under. Yes?

 

Yes. You want to be as close as possible to the max without being over. You will find that unless your clearances were HORRIBLY tight, in most cases you will only be going down one shim size, maybe two. But I have a question: Are you 100% SURE that both the intake and exhaust valves require the SAME clearance? Usually there are two sets of min/max, one for intake and one for exhaust. Not saying they couldn't all be the same, not being a 650 guy, but every bike I've ever had they were different between intake and exhaust. Might wanta double-check.

 

This has been debated before here, and I think they should be different specs, like the 750. It's all engineered the same, so why not?

This could be a factory goof-typo IMHO.

 

Here is what I measured a few days ago:

Exhaust #1 - #4
.006 , .007 , .006 , .005

Intake #1 - #4
.003 , .004 , .004 , .005

The bike has 17k miles. No idea at all about previous owners care and feeding of the valve clearances.

These measurements would lead me to believe that originally the intakes were .004-.006 and the exhausts were .006-.008.

If so, then intake #1 and exhaust #4 are the only clearances out of spec.

Opinions?

 

From the Factory manual for the 650:

Intake valve clearance (cold):
0.11 ~ 0.15 mm (0.004 ~ ~ 0.006 in)
Exhaust valve clearance (cold):
0.16 ~ 0.20 mm (0.006 ~ 0.008 in)

Since shims come in 0.05mm increments you won't find two shims that will fit the specs. Use the one that fits the specified range.

 

You are correct sir! Intake #1 is too tight as is exhaust #4. Now NEXT time you will probably be looking at adjusting intakes 2 and 3 and exhaust 1 and 3. This illustrates the value of taking good notes during the process and keeping a log book. Your clearances are almost exactly IDENTICAL to what I found when I did my '81 550 with 18K miles on it, and I know for a fact it had only been done ONCE in it's life. Yours was probably done once, too.

 

Thanks guys. That confirms what I thought.

Chacal is out of the shim bucket tool right now.

Has anyone used the Motion Pro shim tool for the XJ650J engine?

 

I use the Motion Pro tool on my 550's. I believe I got mine from Bike Bandit for around $15 before I found this site... The tool CAN be a pain in the butt until you discover the secret: The cam has to be at EXACTLY 90 degrees to the surface of the shim then the tool will bolt in exactly right.

 

If the cam is a hair past 90 degrees can you rotate backwards to line it up or do you have to rotate it all the way around again?

 

Would a motor of 10k miles need a valve check? can you tell WITHOUT opening the cover whether this service has been done (gasket wear?)

 

Half; You can rotate backwards, you HAVE TO to remove the tool on one side or another I can't remember which but it's obvious when you're doing it. When rotating backwards, go slowly, on the 550's it engages the starter and drags it along for the ride, don't know for sure on the 650's.

Moon; No way to tell, remember it's a 27-year old gasket and by now it's BAKED. Are you talking about a 750? I'm not sure what the recommended interval for the 750 is, for the 550 its every 5K miles. That being said, back when these bikes were new a valve adjustment at the dealership ran around $200, or more. As a result, it was simply IGNORED by a lot of owners. (The bike runs fine, why bother with something I see no need for and don't understand to begin with?) Chances are better than not, with only 10K on it, that it may have never been done. I'm willing to bet that only about 1 in 10 of these old XJs ever had the proper valve clearance maintenance, if that.

 

how much do gaskets go for? can you make your own out of gasket paper?

The reason i ask is that that gasket on this bike looks relatively fresh... thick dark black rubber, no wear marks on it.... wish i had a camera so i could take a picture

sorry for jacking your thread

 

they run about $60 from chacal and around $80 or something outrageous like that from Yamaha. There are also rubber donuts around the bolts that are critical to providing the proper pressure on the cover to seal it, and should be replaced with the gasket. The bolts themselves have shoulders that limit how tight they can go. The gasket is a complex ribbed molded rubber affair you cannot reproduce yourself. Yours is baked and will crumble in spots when removed, trust me. The "UP" side is that once replaced, the gasket and donuts can be reused many times over, for many more valve adjustments in the years to come.

 

thanks for all the info bigfitz....should one use gasket sealant on these?

 

I use high-tack spray gasket sprayed into a paper cup or can lid or whatever and applied with a small brush to the valve cover. Once "dry" (sticky as HELL) I glue the gasket to the cover, and let the whole shebang set up. Before installing the cover, I smear the other side with gear oil or sil-glyde to help it conform and seal but also allow it to come apart next time.

 

IIRC, the book calls for initial valve lash check at 5,000 miles. 8,000 miles or annually after that.

It's a safe bet you're 27 checks behind............