Bigfitz's AIRHEAD VALVE ADJUSTMENT with Pics - parts I & II

I have been granted permission by to recreate Bigfitz's Valve Adjustment forum. These are his words and his pictures. If I add anything, it will be as "***editor's note".

I hope this helps

Dave

 

OK, it's gonna be a long one, pic heavy, but here we go:

Airhead XJ valve adjustment: We're going to be working on my '83 XJ550 Seca. Since all air cooled XJs use the same procedure for adjusting the valve clearances, here it is:

First off, DISCONNECT the BATTERY. The easiest thing to do is disconnect the ground wire, wrap a shop towel around it and tuck it out of the way.

MAKE IT A HABIT TO DO THIS BEFORE DOING ANY "DISASSEMBLY" WORK ON THE BIKE. It will prevent possible disaster.

Remove fuel tank Be sure to disconnect BOTH lines from the petcock.



Tie up the plug wires so they are out of our way for the duration, I used a piece of string because it was handy.




Remove obstacles On the 550, the flasher relay has to be slid off its mount and got out of the way.




Loosen the cover bolts completely, They won't want to come out, that's ok, just be sure they are fully unscrewed.




And the outers, once again, completely loose but don't worry about lifting them out they may not want to come out.

 

Crack the cover loose I used my patented RickCoMatic carb rack pry tool (wooden hammer handle) pry firmly around it at various spots and it will pop.




Lift cover up until you can see that it will clear the camchain



Slide the cover clear just be careful of the camchain tower



Remove the ignition cover Use an impact driver if the bolts are stuck



Rotate the crankshaft using a 19mm wrench. BE CAREFUL not to crash into the ignition pickup coils.
NOTES: Cams rotate the same direction as the crank. Rotate "forward" (Counterclockwise) whenever possible. There will be times when you HAVE to rotate the motor backwards. GO SLOWLY. On the 550s the starter engages and you drag it along for the ride.

 

Make yourself a chart, for #1, #2, #3, #4 cylinders, both intake and exhaust. I lay the chart out like the motor is laid out it just goes easier.

Rotate the crank (forward, CCW) so that each cam lobe in turn is pointed "skyward" away from its bucket at a 90 degree angle from the surface of the shim, and check the clearance between the heel of the cam lobe and the top of the shim.






Check the clearances on all the valves and record them on your chart.

Now it's time to read some shims.

For any that are OUT OF SPEC, first: Check the location of the NOTCH in the edge of the bucket. ROTATE the bucket (while the lobe is up) so that it is positioned toward the inside so that you can get your shim popping tool into it. Look closely at the exhaust valve (on the left) bucket in the pic below and you can see the notch.




Rotate the motor (still forward) so that the valve you want to check is FULLY OPEN (cam lobe CENTERED on its bucket.)

Place the "tool" in position, hold firmly against the cam lobe and bolt it down. It should sit "square."



Here's a fully open valve with the tool in place.

 

Now for the very important part: With the tool in place, rotate the motor (and cam) away from the tool until the lobe is sticking back up in the air again.
YOU MUST NOT ROTATE THE CAM TOWARD THE TOOL AT ALL. There is enough mechanical advantage here to CRACK THE HEAD. The cam must not push against the tool bad things will happen.
This is where you may have to turn the motor backwards.
Once the heel of the cam is over the bucket (and the tool successfully held the bucket down) you can stick a small NON MAGNETIC screwdriver in there and pop the shim up. IF the edge of the bucket/shim comes back UP beyond the edge of the head casting the tool "missed" and you'll have to do it again. It just takes practice and be sure the cam is EXACTLY centered on the bucket when you bolt in the tool and it will work every time.





Using a NON MAGNETIC TOOL* I prefer hemostats, pluck the shim out.




*Non magnetic tools are important as the shim and bucket are made of an easily magnetized alloy. If they become even weakly magnetized they will attract microscopic particles of metal and accelerate the wear on the cam and shims.

(**Editor's note--- the Factory Service Manuals, though, DO say to use a small magnetic tool to assist removing the shim. personally, I have had no issue doing as such, and the rapid pounding and lobe action will demagnetize anything anyway....and there is a magnet on the oilpan drain-bolt to pick up particles)

 

Read and record the number on the back of the shim, and put it back.



REPEAT ABOVE PROCESS FOR ALL OUT OF SPEC VALVES. If you're seriously anal like me, pull, read, and record them all so you have it for next time.

Keep in mind the valve train tightens not loosens as it wears on these bikes. It is rare to find a "loose" valve, they will either be good or tight, or VERY tight.

Using the valve shim replacement chart, determine what shims are needed based on the measured clearance and the currently installed shim.
Per chacal, all the XJs have the same valve clearance spec except the "X" models and the XJ1100.

 

When installing new shims, make sure they are WELL OILED with clean motor oil. I keep a small plastic tub of oil nearby and dip them just prior to installing. Once again, non-magnetic tools ONLY!!!

INSTALL SHIMS NUMBER SIDE DOWN.

Once all your new shims are installed, rotate the motor FORWARD (CCW) three or four revolutions and RE CHECK all the clearances again. We all make simple mathematical errors on occasion.

Once everything is in spec (and you recorded the shims you installed and the new clearances) it's time to button it back up.

Check your valve cover gasket thoroughly and if it's crispy anywhere, replace it. Take a look at the rubber gaskets on the bolts. You may have to smack them from the back to dislodge them from the cover. Here's why we replace the "donuts"



Look at the thickness of the area where indicated. You can see how the old "donuts" have compressed compared to the new ones.

Note the shoulders on the bolts. The bolts only tighten up to the shoulder and then STOP. The "donuts" are what actually push the cover down against the gasket. I recommend replacing the gasket and the donuts the first time you do this and then you won't have to for a few YEARS and it won't leak.

You will have to get medieval on the old donuts to get them off (I just cut them off) use a dab of silicone grease to pop the new ones on.

Valve cover prep: Here my assistant is applying 'decanted' High-Tack spray gasket sealer to the gasket groove with an old artist's brush. Once it dries, about 10 minutes, it becomes the stickiest stuff on the planet.




Then grease it up The gasket is glued in place so now it gets a good smear of silicone grease prior to reinstallation.




Reinstall the valve cover; remember the stop collars on the bolts so don't overtighten them, torque them to the proper spec which is only 7.2 ft-lb. It's hard to get a torque wrench on the inner ones, so tighten them until they stop and then just be sure they're good and snug.




If you used new donuts and a new gasket it WILL NOT leak.


If you want additional pictures of anything or need anything clarified please just let me know right away while I still have the bike apart. I can always snap more photos, just ask.

I hope this helps, I wish I'd had something similar my first time I only had the Clymer book at that time and it sucks as far as being able to see what they are talking about.

Cheers---Fitz
(**editor's note---Fitz is not available.....if you have a question, ask ' hogfiddles ' )

I hope recreating this is a help.

Dave

 

Part II -- The Tool vs. Zip-tie or Wire Method

ALRIGHTY THEN. THERE SEEMS TO BE A LOT OF CONFUSION AND CONSTERNATION brought about by the use (or attempted use) of the Yamaha valve bucket holding tool for swapping shims.

So here we go with a quick supplement to the original "Airhead Valve Adjustment" http://xjbikes.com/Forums/viewtopic/t=14827.html wherein by using my spare cylinder head I can show you exactly what both methods of propping open a valve entail, and the pros and cons.

So, jumping out of that article:

When the tool is in place and working correctly, it holds down the edge of the bucket when you rotate the cam away: (Look closely just below the cam you can see the tip of the tool engaged with the edge of the bucket.)




What's going on under there is this:




Which is why, in order for the tool to do its job, it needs to be as centered as possible on the cam lobe:



You can see by the second pic if the tool isn't centered in relation to the bucket (and cam lobe) then it can't catch the edge of the bucket in the right spot. If you get the Tool centered on the cam lobe it will work every time.

 

WHICH BRINGS US TO:


THE "ZIP-TIE" METHOD: If you don't have access to the tool, you can use the "zip-tie" method, although I recommend using a piece of insulated solid wire (#12 or #14 will work fine.)

The wire, with a small "J" bent at the end, gets shoved down the plug 'ole and hooked under the head of the open valve, into the port:


("piston's eye" view from inside combustion chamber)

Then when the cam rotates away, the valve can't close all the way:




Which means the shim now has enough clearance to be removed; however, a problem arises: The bucket will invariably want to lift up with the shim, as they're often quite well stuck in there:



Which requires holding down the bucket while you pop the shim out:



NOW WHO'S GONNA PLUCK THE SHIM OUT? You're using two hands already...

This is another reason I recommend use of the tool, once three hands are involved the chance of a shim getting loose and ending up where it ought not increase exponentially.

Further, I don't like probing about in my combustion chamber and risking breaking loose chunks of carbon, or disturbing the nice even carbon "cushion" each valve sits on, which is why I use the tool.

If those things aren't something you feel you need to worry about, or don't have/can't get ahold of the proper tool, then at least you can see why I say to use a piece of wire rather than a Zip-Tie.

It makes it much easier to decide once you understand exactly how each method works.

Hope this helps, and as always, let me know if anything needs to be clarified or you'd like another picture of something I missed.

 

For the remainder of the forum, questions, and discussion--- that is all still on the original forum:

http://xjbikes.com/forums/threads/airhead-valve-adjustment-with-pics.14827/