AIRHEAD VALVE ADJUSTMENT with Pics

Hold on. "Ground the shims?" NOT a good idea; they're not hardened all the way through.

One of the forum members is a metallurgist; he sliced a shim and analyzed it with some very sophisticated instruments and posted the results. The bottom line is that grinding shims is not a good idea.

Better to simply replace with a shim that puts you within the specified range.

 

thanks for this bigfitz, It was a huge help!

How did you get the metal lines on the cover so shiny? I tried to polish mine by hand but they still look dull/dirty

 

You're more than welcome; that was the whole idea. The pictures in both books leave a lot to be desired.

The polished aluminum on these bikes was lacquer-coated originally. Quite often the gray stains are UNDER the old clearcoat; it needs to come off first.

I did a complete "how-to" when I did that valve cover; it's in "FAQ Suggestions" as well: http://xjbikes.com/Forums/viewtopic/t=22125.html

The techniques applied here can be used effectively all over the bike.

 

Possible correction:

You say to point the lobes "skyward at a 90 degree angle" Do you mean 180 degree angle? Should the "point" of the lobe be pointing directly away from the shim, like this?

| O>

because the backs of the lobes are not always round, and I've found that it often gives a larger gap reading at 90 degrees, then tightens back up near 180 degrees.

 

Gotta love trig! This is what bigFitz meant by 90 degrees I think. If you think of the flat surface of the shim on the lifter as being the x-axis, then the lobe would be pointing 90 degrees away from the x-axis/shim surface and be the y-axis. If you think of the stem of the lifter then you are 180 degrees away from the direction the stem goes when the valve is opened.

This picture is from an Alfa Romeo but I think it conveys the idea

 

I SAID "at a 90-degree angle to the SURFACE OF THE SHIM"; which is 180 degrees from the direction of the valve stem, true.

The above diagram is a perfect representation of what I meant to indicate.

 

Finally sat down and opened the valve cover to check the valve clearances.

After 47,000 Miles & never ever been done before I had the following:

Exhaust: .007" .004" .006" .003"

Intake: .005" .004" .004" .005"

I am ordering new shims today to bring them back into spec.

Question: The manual says to check every 5K, Could changing the oil every 2500 miles and running 91 octane have allowed me to run so long (47K) without the clearances being any worse?

 

Amazing, Bud, at your worst case the shim is wearing at just 0.012 / 5000 miles. May I ask how you ride this machine? Wiz.

 

Shims don't wear appreciably; the valves burrow into the head. He must 'baby' it. PGDBUD, please start a new thread; you've posted this here and in somebody's Max-X adjustment thread, and it's worth discussing on its own merit.

 

Thanks, Fitz, of course it's not the shim wearing.

 

Excellent job Fitz, my wife and I just returned from Florida after 2 1/2 weeks there missing checking into XJ Bikes. Seemed like I was Disconnected being there with out my computer. I can see though that while I was gone you guys did nothing but get better here in the web site. It sure is a shame I didn't have all those nice pics years ago when I was much deeper into the motorcycles. Seems like just about everyone rides a motorcycle down in Florida. Doesn't seem to matter if there 20 or 80 years old either. One thing I found out when I was there is that last year as I am told the State of Florida increased their State Homestead exemption on property taxes to 50%. Boy with the prices of houses there a guy could sure buy a nice home for cheap and still have cheap property taxes. Something to think on for me. Once again Fitz--->GREAT JOB WELL DONE! grunt007, 81'XJ 750 Seca, Mi.

 

Excellent write-up, Fitz. I dont think i would have even attempted this without your guide. This is exactly what a service manual / technical write-up should look like. I just wanted to sincerely thank you for all your contributions to this site, including of course the rear brake delamination warning. You are both a saint and a scholar good sir.

 

Excellent write up here. I'm a newbie and this write up really helped to muster up the courage and do this. I do have one issue I would like cleared up. I have an 1982 XJ650J Maxim and according to the Haynes book it called out that spec is .16-20 for both the in and exh. But reading through this thread it appeared pretty unanimous that spec is .11-.15 for in and .16-.20 for exh. For my XJ650J is the Haynes manual correct or is this post correct? Because that would change alot of what I need to do.
Cyl 1 2 3 4
Ex .178 .127 .178 .127
In .102 .127 .152 .127
As you can see depending on who's advise I take I could either be at replacing 6 or 4. And for me it's not the work I'm concerned about...it's the operating that concerns me most.

 

The Haynes manual is INCORRECT on that particular detail.

The correct intake spec is indeed .11mm~.15mm.

I only see 3 that need attention, if those are metric numbers (from an American gauge) exhausts 2 and 4 are too tight, as is intake 1. Intake 3 is fine, drop that .002mm and call it .15.

Get yourself a metric feeler gauge; it makes this a lot easier. K-D Tools' #2274 is widely available.

 

Thank you for the confirmation regarding the Haynes manual. I ordered my shim tool and will swap those three out. I do have a metric feeler gauge but thanks for the reiteration on that. Thanks again and I always appreciate your technical knowledge.

February 18, 2012
-I Just replaced Exhaust 2 & 4 and Intake 2 today...finally found the time...Fitz thank you! Your write up made swapping these out NO PROBLEM! And now they are in spec and ready to move onto carb work.

 

Thanks for the nice right up and pictures Fitz! I hope somebody will post pictures and how to for Maxim X too.
Where in Michigan are you from? I am from Macomb County.. Maybe I can come to your place (with beers and chips of course) for a carb tutorial, or mechanical tutorial....

 

http://xjbikes.com/Forums/viewtopic/t=16298.html

Maxim X adjustment.

 

Thanks for the great info Fitz! Going to give it a go this weekend.

Where can I get my hands on some replacement 'donuts'? What are they officially called so I can search for them?

 

Ok so I guess they're "Valve Cover Bolt Seals" ...

This is the cheapest I could find them at $20 for 10.
http://www.jpcycles.com/product/ZZ26668
Everywhere else wanted $6 for 1. Am I doing something wrong? What's with the insane markup? I mean, the expensive ones are OEM, but still.

I'm just not sure these will work though as the K&L catalog lists them for XJ550/XJ750. It's not a different part for the 650, is it?

 

The "donuts" for the 550, YICS 650 and 750 are the same; HOWEVER:

Not all 12 of them are alike. The ones on the eight outer bolts are different than the ones on the four inner bolts.

Did you price them with XJ4Ever?