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AIRHEAD VALVE ADJUSTMENT with Pics

Discussion in 'XJ DIY How-To Instructions' started by bigfitz52, Jan 6, 2009.

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  1. bigfitz52

    bigfitz52 Well-Known Member

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    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.

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    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.

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

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

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

    [​IMG]



    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

    [​IMG]


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

    [​IMG]


    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.

    [​IMG]


    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.

    [​IMG]

    [​IMG]



    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.

    [​IMG]



    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."

    [​IMG]


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

    [​IMG]


    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.

    [​IMG]



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

    [​IMG]

    *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.



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

    [​IMG]



    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.

    [​IMG]


    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"

    [​IMG]

    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.

    [​IMG]


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

    [​IMG]


    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.

    [​IMG]


    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
     

    Attached Files:

    Last edited by a moderator: Aug 20, 2017
  2. greggvickrey

    greggvickrey Member

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    Fitz,
    a masterful job, well done. this is probably next on my list to do. thanks again.
     
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  3. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    Fitz......exceptional. And a very nice watch, too.

    P.S. the engine will become much easier to turn over with the wrench if you remove the spark plugs.

    Also, the valve shim clearance are the same for all the XJ-series bikes except the XJ700-X (waterhead) models, and the XJ1100's:


    Valve Clearances:
    -always measured with engine at "room temperature":

    550:
    Intake: 0.11 - 0.15mm ( = 0.004 - 0.006")
    Exhaust: 0.16 - 0.20mm (= 0.006 - 0.008")

    650 all x. Turbo:
    Intake: 0.11 - 0.15mm ( = 0.004 - 0.006")
    Exhaust: 0.16 - 0.20mm (= 0.006 - 0.008")

    650 Turbo:
    Intake: 0.11 - 0.15mm ( = 0.004 - 0.006")
    Exhaust: 0.16 - 0.20mm (= 0.006 - 0.008")

    700 non-X:
    Intake: 0.11 - 0.15mm ( = 0.004 - 0.006")
    Exhaust: 0.16 - 0.20mm (= 0.006 - 0.008")

    700-X:
    Intake: 0.11 - 0.20mm (= 0.004" - 0.008")
    Exhaust: 0.21 - 0.30mm (= 0.008 - 0.012")
    NOTE: special tapered-point feeler gauges needed due to extremely cramped working environment on these bikes; also, the X-models use a unique valvetrain that uses "pads" rather than "shims" and basically takes all day to perform the check, and about as long if you have to replace any of the pads on the 20 total valves!

    750 M/MM:
    Intake: 0.11 - 0.15mm ( = 0.004 - 0.006")
    Exhaust: 0.16 - 0.20mm (= 0.006 - 0.008")

    750 Seca:
    Intake: 0.11 - 0.15mm ( = 0.004 - 0.006")
    Exhaust: 0.16 - 0.20mm (= 0.006 - 0.008")

    900RK:
    Intake: 0.11 - 0.15mm ( = 0.004 - 0.006")
    Exhaust: 0.16 - 0.20mm (= 0.006 - 0.008")

    1100:
    Intake: 0.11 - 0.15mm ( = 0.004 - 0.006")
    Exhaust: 0.21 - 0.25mm (= 0.008 - 0.010")
     
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  4. Galamb

    Galamb Member

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    Fitz, what a beautiful job. That's the way the manuals should have them. But then nobody would have to ask any questions. :D
     
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  5. Fishmaster

    Fishmaster Member

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    GREAT JOB Mr. FITZ!!!!!!! Thank you for share it.
     
  6. bigfitz52

    bigfitz52 Well-Known Member

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    True. However, a really smooth motor with the plugs out can actually "coast" a bit, forward or backward, in response to the pressure from the valves on the cams. Leaving the plugs in means the motor stays exactly where you put it and forces you to go slowly. On a 650 or 750 you probably need to pop out a plug or two.

    I probably should have mentioned that the camera I used is a Canon SX110 IS, and it takes pictures at 3456 X 2592 (by default.) I then resized them to 1024 X 768 using Adobe Photoshop.
     
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  7. Hack

    Hack Member

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    Great job, Fitz. Thanks!
     
  8. kontiki

    kontiki Member

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    Excellent. Much appreciated.

    Thanks for the handy clearance chart Len, I'm printed it and stuck it in a plastic sleeve in my 'XJ' notebook (book containing secret information gathered over time from here).
     
  9. bigfitz52

    bigfitz52 Well-Known Member

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    Since chacal cleared up the clearance issue (did I make a funny?) I will edit the post to include the shim replacement chart as soon as Photobucket starts behaving itself again.
     
  10. MikeT

    MikeT Member

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    Great Job. Very informative. Was also wonding if anybody has done the same with a maxim x. I have an 1985 750 maxim x and was thinking about doing a valve clearance check, but like chacal mentioned, the valve train looks prety cramped. Was just looking for some advice or pics to help. Thanks
     
  11. bigfitz52

    bigfitz52 Well-Known Member

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    Shim chart added
     
  12. TIMEtoRIDE

    TIMEtoRIDE Active Member

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  13. moonfriedpotatoes

    moonfriedpotatoes Member

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    nice!! definitely sticky-worthy. thanks fitz
     
  14. Planehue

    Planehue Member

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    Thank you for your tme on this project. I just this afternoon took the valve cover off and had a look. Naturally my feeler gauges are at work. Oh well , next week. With your information and the great pics the job will be done much faster. I will be looking for a new gasket and rubber mounts, any suggestions as to where to get or order from.
    Bike is a 1983 750k. Thanks :D
     
  15. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    Planehue, I carry all the parts you'll need, just follow the link below in my sig line.......
     
  16. xj650ss

    xj650ss Member

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    thanks fitz! I was just about to search this topic when i saw your post great timing thanks again
     
  17. dqnjuan

    dqnjuan Member

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    Great write up! Had mine all recorded in a lil over an hr with this forum. 5 out of 8 too tight yikes. And a piece of 12 gauge elec wire worked great as a valve tool.
     
  18. bigfitz52

    bigfitz52 Well-Known Member

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    UPDATE: Got all the shims in; even the one that was "in spec" was right at the tight side so I dropped down a size on it too.

    In case you're interested here's where we ended up:

    Cyl: #1 #2 #3 #4
    EX .18 .18 .17 .19 (spec is .16-.20mm)

    IN .13 .12 .14 .12 (spec is .11-.15mm)

    I recorded all the shims installed as well.
    I'll be paying close attention to EX #3 and IN #2 and #4 next time around, but I feel MUCH better about this motor now.
     
  19. Senadin

    Senadin New Member

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    Is there such a good write up for Maxim X?
     
  20. MN-Maxims

    MN-Maxims St. Paul Minnesota

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    Fitz, Can you explain the "feel" of the feeler gauge when you check your clearances.
    I've always just adjusted till I could feel a slight drag on the gauge when you pull it back.
    Thanks
     
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