AIRHEAD VALVE ADJUSTMENT with Pics

Wonderful post bigfitz, I guess it would look alike internally for XJ700 (non X).? any idea !!

 

I have a '80 XJ650. The only gasket available is paper.

Will the gluing technique work on a paper gasket?

If not, are there other techniques I can use to re-use the current gakset (if not "crunchy") or the new one I just got from chacal?

I want to be able to ride my bike while I wait for the new shims to arrive.

Thanks.
Jim

 

littlegiant It's my understanding all the "airhead" XJs are the same; the only difference being some of the bigger bikes might have less room to work in there

AND the pre-YICS motors have different hold-down bolts and gasket, which brings us to...

minturn yes it will work fine on your paper gasket. I used the same technique on my clutch cover and ignition cover gaskets and they are perfectly reusable as long as you grease or oil the "release" side.

 

Okay, I am getting seriously grumpy here.

I have followed these directions to the letter, as well as some adaptive measures given by MjCarl elsewhere.

First I tried centering the lobe on top of the bucket and seating the tool, pushing the tool firmly against the cam. When I then rolled the motor forward to have the retaining tool hold down the lifter, the tool was completely ignored and the bucket came all the way up and there was no slack on the shim.

I followed MJCarl's advice to not have the Cam lobe centered on the bucket and roll it forward a bit. Still no contact. I held the thing in place and cranked the motor around and there was never any contact of anything with the tool, until the cam lobe came near, of course.

I blew well over four hours on this today and am more than a little cranky. It seems the retaining tool never makes contact with the lifter

 

QUESTION:
The numbers have smeared and are illegible on some of the shims that I have taken out. Is there a way to know what number the shims are without looking at the numbers on the back?

 

Mike; I too was ready to tear my hair out the first time I used the tool. Carl's directions are correct, the cam lobe has to be away from the tool and pushing the bucket down. I have better luck if the cam has almost pushed it down all the way; and then push the tool against the heel of the cam and ensure the tip of the tool is centered on the edge of the bucket.
(This is impossible to do except by guess and by golly since you cannot see the tip of the tool.)

I can tell you this: Once you DO get the hang of it, it works 19 times out of 20.

Motorduck: Measure them. You can get a cheap digital caliper for under $15 these days, and quite decent ones at that. Or take 'em to your corner auto repair shop and have them mic' them for you. A 260 shim is 2.6mm thick; a 245 is 2.45mm, etc.

If that's not possible, swap in one you CAN read, and measure that new gap and reshim accordingly.

 

thanks bigfitz.

 

I finally did get the knack of it Fitz. It sure would be nice if that damned tab was a mm or so longer. It is a *real* major PITA to get the shims out of the center buckets. You have no room to manuever and can only come at them from one direction. Damned near impossible. Having that bucket down another mm or two would make a heck of a lot of difference by adding that much more clearance.

 

getting the notch in the bucket so it ends up in exactly the most advantageous spot for popping the shim loose is part of the art as well; I still curse at myself when I've got the tool in place and the bucket is down but the notch moved so a do-over is in order...

I'm glad you got it finally.

 

Hear hear! We poor X owners have it hard enough. There is a thread here but not much detail. I pulled the tank, decorative pieces, horns, coils, and then the eight bolts on the head cover. Pull the ignition cover same as in Fitz's guide here. Using a narrow feeler gauge set from Chacal it was easy enough to measure the clearance. Apparently we have to pull the cams off the top to get the pads out - that's my next step.

 

One question, How do the valves get tighter over time? I know they do,,, but how? I am no vulcan, but this doe not seam logical.

 

The relatively huge shim-and-bucket actuating mechanism doesn't wear appreciably; what DOES happen is the valves pound themselves into their seats, as both the valve seat and the valve itself wear.

As the valve pounds into the seat, the clearance at the top decreases.

 

I love this write up. It will really help alot when I do my first valve check. Now for the noob question. Am I correct in stating that the exhaust valves are the ones closest to the headers? I want to make sure so I really don't screw up my readings. Thanks

 

Yes. The exhaust is closest to the headers, and the inlet is on the airbox side. I used this same write-up when I did my adjustment. If it were not for this write-up I probably would not have been able to do mine by myself.

 

Fitz, your directions BEAT the clymer by 110% at worst. Will you be my friend? Haha.

 

Got a question for anyone listening.

I measured the clearances over the weekend. Pretty much everything's a little tight (.102mm), so lots of replacement shims coming up. But there were two valves (one intake, one exhaust) that I couldn't fit even the smallest gauge under (.0015"). I swapped that shim with another, rotated the engine a couple times, and tried again: still no room. What would you suggest I do here? Do I order a tiny shim and measure using that, or is there a way that doesn't require my placing two separate orders?

Oh, btw, great guide Fitz.

 

What sizes are in there now?

I would install a shim two or three sizes smaller and measure from that.

I have a small collection of used shims I have loaned out in the past to others who have had this problem; depending on what's in there (and what I still have) I could send you a couple to try.

 

The shim originally in there was 285 (I think, very hard to read). I tried replacing it with a 275, to no avail. I'll order some extra, smaller shims when I replace all the other out-of-spec shims. Thanks for the offer though, Fitz.

 

Even if the Numbers are impossible to read, ... Just Measure the thickness of the Shim with a Micrometer.

When you have No Clearance to calculate from, ... Borrow a Shim from another Valve and use the Borrowed Shim to give you a measurement or solution.

You could get lucky and borrow the right Shim and get the right Clearance.
You might not be lucky and have it out of specs.
Use the Value of the Borrowed Shim to give you a baseline to work from.

 

quick question:

does anyone recommend loctite or never-seize for the reinstall? i'm guessing i don't want either on the valve cover screws - don't want any of that stuff coming off the screws and finding it's way into places it shouldn't be - but what about the left side cover?

part of me thinks loctite - don't want those screws to work their way out, but i'm afraid i'll end up ruining the screw if and when i ever want to pull them out again - which leads me to think never-seize, but then i'll have to worry about those screws coming loose and falling out, which brings me back to loctite . . .

any thoughts?