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intake valve depth off

Discussion in 'The Garage' started by chunts, Apr 9, 2012.

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  1. chunts

    chunts XS650 Enthusiast

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    so here's the backstory. 81 xs650 that I purchased not running and missing a few pieces. I've been putting it back together for a couple of months and recently got in running. it runs like garbage. low compression on the left cylinder around 100 psi. right is 125-130. left cylinder seems to be running rough, stumbles and pops. right cylinder is better but backfires into the air filter occasionally. mixture is obviously rich. plugs are black, exhaust smells like fuel. carbs have been rebuilt and I put pod filters on, so bumped up the pilot and main jet one size as a place to start.

    had some exhaust leaks because of a bad muffler install, fixed that. runs a little smoother now, but right cylinder seemed to have not been firing at first, but it caught on later. dosen't idle well and often dies.

    adjusted the cam chain tension yesterday and got that right, it was way loose. i can hear what seems like a leak from the intake valve when i turn the crankshaft with a wrench, but i'm not sure.

    today I cracked it open to adjust the valves and right off the bat, the intake valve on the bad cylinder is jammed down so it's not flush with the top of the spring. basically I can't even get a feeler gauge in there to check the clearance. also looking through the spark plug hole the intake valve appears to push much further down than the exhaust valve does.

    here's the valve from the top:
    [​IMG]


    here's the intake valve open inside the chamber:
    [​IMG]

    so what do I do to fix that valve? Do I have to pull the engine and tear the top end apart? my guess is it's not seating right which explains the bad compression.
     
  2. Probably have a bent valve stem. Motor out, head off. If you've never done this before, don't worry, it's not as hard as you may think.
     
  3. angus67

    angus67 Welder's penetrate deeper!!

    new guide, valve, lap, done.

    sounds easy, huh? thats once the motor is out, wich includes droping the chain, taking out the motor mounts, breaking your back getting the motor out of the fram.
    And once you have the head off, fresh ring/hone? new chain guide? new this, better that? moto engines are a can of worms.
    but if it runs now, you could keep it minamal repair to get back on the road, and do those other things later
     
  4. bloodhound

    bloodhound XS650 Addict

    It is so much easier that you think.
     
  5. chunts

    chunts XS650 Enthusiast

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    so i took the engine out and got the cylinder head cover off and this is what I found:

    [​IMG]

    looking at the valve spring itself, it looks like the retaining clip for the bad valve is missing completely, which explains why the valve end is not flush with the spring. and from the look of the damage here it probably came off and got bounced around in there chewing up the aluminum.

    it doesn't look to have damaged anything important though besides the breather hole. can I just dremel out the rough edges and still use this cover? the rocker arms appear to be fine, though i don't know where all those aluminum chunks and the clip itself ended up.
     
  6. 5twins

    5twins XS650 Guru Top Contributor

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    Yes, you can probably clean up the rough edges and use the cover. From your 1st photo, the valve keepers appear to be there, just inset too far into the spring retaining washer. That retaining washer may not be a 650 part. The hole through the center may be too big, allowing the keepers and valve stem to sit in too far. I've also never seen one with the step in it like yours. They're flat across the top .....

    [​IMG]

    I guess it's possible the springs and top washer are from another bike. I would compare the springs to the others.
     
  7. chunts

    chunts XS650 Enthusiast

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    thanks, I didn't notice that. I'll compare it to the others and see what's up.

    wouldn't be surprised if that's an odd part. whoever owned this bike before sure liked to use whatever they had around. I had no less than four different types of nuts holding the valve tappet covers on, and half were missing a nut anyway.
     
  8. That looks like an aluminum retainer. Jack gave a heads up on about not running them in a street motor. I Questioned him about it and later retracted my statement. If you have them in your motor best to check them often. They are for racing. Best to buy titanium for a street motor or use the stock steel ones, if you have a need for high performance valve springs for a race cam and you run it on the street. Most racers adjust valves often and check retainers when they do. :thumbsup:
     
  9. chunts

    chunts XS650 Enthusiast

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    thanks. I just ordered a stock one to replace it. I have no interest in high maintenance parts :)
     
  10. Looks like you caught it just in time. Check the end of the valve for damage where the keepers go.
     
  11. chunts

    chunts XS650 Enthusiast

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    the saga continues. got my valve spring compressor today. the other three valves came out really easy, but the odd one with the wrong retainer absolutely will not budge. the valve itself moves, but it looks like the keepers are completely wedged in there and don't want to come out so the spring won't compress in the tool.
     
  12. 5twins

    5twins XS650 Guru Top Contributor

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    Block the valve head from underneath in the combustion chamber so it can't bounce open and then use a suitably sized socket and short extension to pound down on the retaining washer from above. Hopefully that will break it free on the stem.
     
  13. chunts

    chunts XS650 Enthusiast

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    couldn't get it to budge. guess i'll try a hydraulic press next.
     

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