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Cam Tensioner Issue

Discussion in 'The Garage' started by wally_nd, Apr 26, 2015.

  1. wally_nd

    wally_nd XS650 Member

    Here is a bit of history before I get into the actual question. I purchased a 1980 XS that had been stored in a shed since aprox 1990. The story goes that the original engine blew up and the guy bought an engine that had less than 1k miles on it and put it in but never could get any spark. I found that the engine was a points engine and of course the 1980 XS electronic ignition. That would explain why he wasn’t getting spark HAHA. :D He had tied the leads coming from the points into the wires the pick had been tied to. :wtf:



    My engine # is 2F0-108118. In the tech forum i found a chart that say XS-F 78-79 2F0-020101 to (100000). My number is 8118 above that but i don't see another reference to the "2F0" prefix until about 200000. So i will assume my engine is a 79?

    Also with reference from the tech section believe the chain tensioner i have is style "d"
    [​IMG]

    Some additional history that my be relevant, i removed the heads and jugs, inspected the rings, checked the bores, checked the valve guides, and lapped the valves. I replaced the front cam chain guide and assembled the engine. While still on the bench i adjusted the cam chain tensioner so pin was flush, and set the valves.

    This morning i fired the engine up and got it warm, put a timing light on it and got that pretty close. While doing that i noticed some top end noise but to be honest i don't have much xp with these engines so i don't know whats normal. I decided to go through the cam tensioner adjustment again and check the valve lash and this leads me to my question as i am aware if the cam chain isn't adjusted properly you wont be able to set the valves correctly.

    I adjusted the tensioner bold as shown below.
    [​IMG]

    when i turn the engine over there is one point during the rotation the pin pops out as shown below
    [​IMG]

    Also you will notice there is not many threads still showing to put the acorn nut on.

    First question that i didnt really understand from the how to video in the tech forum. Is the pin supposed to move in but adjust the bolt so the pin doesn't pop out past flush? I i tried to loosen but it didn't seem to help. i took the bolt all the way out and noticed there wasn't a washer between the spring and the adjuster bolt. see below.
    [​IMG]
    I know know some of the tensioner styles had a washer here but i cant find a exact reference to the style "D" tensioner.

    bottom line, if anyone can give me some feedback as to any of the assumptions above if they are correct and some clarification to the adjustment and part I may be missing. I would appreciate it very much :)

    I did find one reference to a damper part number 341-12232-01-00 but it seems it wasn't available and it wasn't clear if i was looking at the correct parts list.

    [​IMG]
     
  2. 650mark

    650mark XS650 Enthusiast

    you should have about 5-6 threads showing onto which you screw the acorn cover. get that done first, then the "pin" should go into and out of the tensioner housing an equal amount. best checked when the engine is running. just look at it while the engine idles when warm. you'll see what I mean as soon as you run the engine. ps you'll only drip a tiny bit of oil while checking.
     
  3. wally_nd

    wally_nd XS650 Member

    650mark, any comment on the possible missing washer?
     
  4. angus67

    angus67 Welder's penetrate deeper!!

    yup. missing washer. just go to a hardware store and find a copper or brass washer that fits. any thickness is fine. I found a suitable washer in a harbor freight assorted pack and quieted the tensioner right down. My pin on my 1980 motor pops out like that too when I roll it over by hand, but running, it is fine. You should have more threads than that for the acorn.
     
  5. gggGary

    gggGary Stop that! XS650.com Supporter Top Contributor

    It pops out because the rocker arms going up and down the cam ramps shift tension back and forth between the front and rear side of the chain. I like to adjust with engine idling, tighten just until the plunger stops moving back off 1/3 turn, done. I think WER first described that way of doing it.
     
  6. 5twins

    5twins XS650 Guru Top Contributor

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    I think you should have replaced the cam chain as well. The way that adjuster is so far in is a good indication that chain is toast. And it's a good idea to upgrade the type D tensioner to a type E. That D style tensioner is probably partly responsible for the cam chain being so far gone.
     

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