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valve clearances way too tight

Discussion in 'XJ Technical Chat' started by arniepyeinthesky, Nov 18, 2017.

  1. arniepyeinthesky

    arniepyeinthesky New Member

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    Hi guys.

    thanks in advance for any help.

    My carbs are out on a xj750, waiting for some replacements parts. So I thought while I'm waiting I mind as well check the valve clearances.

    Every valve is extremely tight, can't even squeeze the smallest feeler gauge through.

    Could this be because the bike has not run for a few years? Or it doesn't matter, and they should they all be changed now?
     
  2. XJ550H

    XJ550H Well-Known Member Premium Member

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    yes the shims need to be corrected, you may be able to swap some around
     
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  3. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    1. No, it's not because it was sitting for a few years. Valves recede into the head from RUNNING, not from not-running

    2.I question how you did your measuring....... It's highly unlikely that every single one is out. What gauges did you use? What procedure did you use? How many miles on the bike?
     
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  4. rocs82650

    rocs82650 Well-Known Member

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    +1 what they ^ said.

    Gary H.
     
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  5. JetmechMarty

    JetmechMarty Active Member

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    I did an XS1100 yesterday. It has 16K miles and it wouldn't surprise me if they've never been done before. The intakes are all still in spec, though on the tight side. All four exhaust valves were out. One shim size brought them all back in. I only had to use two shims that weren't in the head.

    Do a compression test before you adjust the valves. If they're as tight as you say, the compression will be low. It's going to be tough to know what shim you need without a measurement.

    See post #3.
     
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  6. arniepyeinthesky

    arniepyeinthesky New Member

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    I took the measurement with the cam lobes pointing directly away from the shims (i.e. pointy part of the cam lobe opposite to shim)
    I used a .005 in feeler gauge, i think only one exhaust it fit under.

    But I haven't had the bike run yet. I inherited it from my late father, I know he had the bike running, but hasn't in atleast 8-9 years.

    The clearances being too tight means the valve is not even fully closing during power stroke right?
     
  7. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Not necessarily.

    Too tight simply means too close to the cam to be in-spec. It means the valve opens too soon, and closes too late, causing lowered compression and lowered power. If the shim gets to where it rides on the cam all the time and there is literally zero clearance, then yes, the valve is not fully closing. But we need to know what your clearances are so that we can get the right shims in to get you back in spec.

    Is that .005" or .005mm? Big difference.......measure in mm, please.
     
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  8. arniepyeinthesky

    arniepyeinthesky New Member

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    .005 inches / .127mm. My feeler gauge is imperial. That's the smallest one on the tool. I should probably buy a thinner gauge (if they sell them thinner?)

    Bike has about 35,000 miles.

    I understand why the gaps would get bigger, from the valve head slowly wearing out and receding into the cylinder head . How the heck would it get smaller?

    thanks guys
     
  9. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    The gaps won't get bigger. They get smaller. As the valve recedes into the head it is moving farther away from the piston, which mean's it it getting CLOSER to the cam.

    Your feelers are too thick to begin with.
    Your intake clearance in-spec range is: 11-.15mm
    Your exhaust clearance in-spec range is: .16-.20mm

    So your exhaust ones may be all tight, but you aren't thin enough to tell whether. Your intake ones are out of spec or not......

    Now, that all said, if you're talking about a 750X, then that's a whole different ballgame.....
     
  10. cgutz

    cgutz Well-Known Member

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    Be sure to buy true metric feeler gauges. You will be glad. I tried to use "English" feeler guages that were marked for "metric", and too frustrating. Bought a set of true metric feeler gauges, much easier and more precise.

    IMHO the good old USA should just switch to metric and be done with it....
     
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  11. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    OP is in Toronto
     
  12. kosel

    kosel Active Member Premium Member

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    I also recommend buying an extra, thin shim. I keep one in my valve shim kit. That way, if anything is that tight, you can just swap it out and take the measurement. I can get them for about USD $10 at a local dealer. Cheap investment to avoid long waits in the future.
     
  13. arniepyeinthesky

    arniepyeinthesky New Member

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    OP is from Toronto, but we are just as imperial as you guys. I went to this auto/hardware store called Canadian Tire, and literally all they have are imperial measurements tools..

    First i'll buy a proper feeler gauge and take it from there.

    Do you guys know what the diameter is for the shims? So i can buy them after i measure before i take the out!
     
  14. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    29mm.... but before you buy, check the shim pool.

    Funny-- I can buy metric feelers as easily as SAE feelers in the middle of NY
     
  15. arniepyeinthesky

    arniepyeinthesky New Member

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    Whats the shim pool? I hope there is a shim hot tub as well :)
     
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  16. XJ550H

    XJ550H Well-Known Member Premium Member

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    GearWrench - Metric Feeler Gauge Part # 2274

    KD tools part #2274 any auto parts store can order it for you using the KD tools part number
     
  17. XJ550H

    XJ550H Well-Known Member Premium Member

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    yup you just jump right into a tub full of shims...

    there is a shim pool where you swap out your unneeded shims for shims you need.

    post your clearances and shim size you have
     
  18. XJ550H

    XJ550H Well-Known Member Premium Member

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    [​IMG]
     
  19. cgutz

    cgutz Well-Known Member

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    Uxcell Metric feeler guage for $5.75 ...if you have Prime shipping it will be there in 2-3 days.
     
  20. MattiThundrrr

    MattiThundrrr Not a guru

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    No. We. Are. Not. What's the speed limit on the highway. 100 miles? Nope. What does gas cost, $1.16 a gallon? I am surprised that your Crappy Tire didn't have metric, every tool set I have ever bought had both metric and imperial.
    Sorry, I seriously dislike imperial. With all my 5'10", 200 lb body. Dammit.:mad:
     
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