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So it begins.....

Discussion in 'The Garage' started by sweatybetty89, Aug 13, 2021.

  1. sweatybetty89

    sweatybetty89 XS650 Addict

    Could not get my timing set Cam was not in the relation that it should have been to my crank. At top dead center it's about at 10 o'clock. Leaving my timing way to advance.Try taking Meet out of the back plate Of my points . Called Gary told me that the guide could have slipped on my Cam Chain Tensioner. dropped my oil and found aluminum flakes in it. If anybody's got any suggestions before I go taking this motor part I'm all ears.
     

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    gggGary likes this.
  2. Jan_P

    Jan_P XS650 Guru Top Contributor

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    Thinking out loud
    How much Aluminum flakes
    10 o clock difference ???
    How do you check TDC and ignition timing with what ignition if points there is an advance mechanism unit that can be a factor.
     
    gggGary and Raymond like this.
  3. Raymond

    Raymond XS650 rider & fettler XS650.com Supporter Top Contributor

    Like Jan, I would ask how you are checking TDC and the camshaft position.

    My bike came to me with an overlength camchain, so the tensioner could not take up the slack. With the engine set at TDC, using the alternator markings, the wee hole in the camshaft on the right was in this position:

    PICT1844.JPG

    That's about 24° retarded at the cam, which is about 48° retarded at the crankshaft. PO managed to get the engine to turn without valves hitting pistons by setting the valve gaps really loose. Engine had to come out to get it all sorted - I didn't know it was the camchain being too long when I took this picture.

    More questions. How long have you had the bike, have you had it running, have you worked on it, anything else that sheds light on what's wrong.
     
    gggGary likes this.
  4. sweatybetty89

    sweatybetty89 XS650 Addict

    I had the bike running and i did have the timing set statically to my F mark at one point and time. I have had the bike now going on 8 months and have had issues with the timing since i got it. at first the the number one cylinder was getting real hot when i would have it started. then it moved to the number 2 cylinder. then i got the timing and valves and cam chain dialed in and it stopped smoking and over heating. She sat for a bit as life happened in the way it does and I came back to start it one day and it was kicking back like a mule. checked timing at that point and saw that it was advanced got it set again by setting cam chain and points gaps. It set for a lil bit and again was out of time. Now will not get close . my cam looks much the same as the pic you posted. but it is a lil less degrees maybe 20 or so and it is advanced.
     
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  5. sweatybetty89

    sweatybetty89 XS650 Addict

    not a ton of aluminum enough to notice and yeah the 10 o clock is where the pin is pointing on the cam shaft. i checked tdc by mark and also feeling the piston. the mark is correct.
     
    gggGary likes this.
  6. nj1639

    nj1639 Paleo-simplistic Top Contributor

    Oi.....
    I picked up a junker some years back for the price of a title.
    Timing was off so I reset it. Tried kicking it over and the engine would seize. Timing would be off again.
    Seems the lower gear on the crank that links with the cam by the camchain was missing a few teeth.
    Looking at the bottom of the engine through the removed sump opening should allow you to check for that.
     
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  7. sweatybetty89

    sweatybetty89 XS650 Addict

    yea i was think that removing the sump would be a good first option
     
    gggGary likes this.
  8. 5twins

    5twins XS650 Guru Top Contributor

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    Wow, missing teeth on the crank cam sprocket, that's a new one for me, lol. These poor old bikes, lol. For what it's worth, I don't think that's a very common occurrence. First I've heard of it as I said. More likely just a badly stretched cam chain, maybe to the point it has jumped a tooth or two on the sprocket. That would throw the cam timing off like you're seeing.

    Your '77 model has the notorious type D cam chain tensioner assembly with no lock nut. The acorn cover nut acts to lock it down. Unfortunately, tightening the acorn nut can also tighten your adjustment along with it, resulting in a chain that's too tight. This will lead to premature chain stretch and wear.
     
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  9. sweatybetty89

    sweatybetty89 XS650 Addict

    yeah i dont think that the crank cam sprocket is missing teeth but the chain is stretched and the guide has come loose so im going in to see whats what. Is there a after market cam chain guide that is not as prone to the so called notorious problem
     
    gggGary likes this.
  10. 5twins

    5twins XS650 Guru Top Contributor

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  11. sweatybetty89

    sweatybetty89 XS650 Addict

    this will not fix the back guide will it? what is the rubber piece that has slipped? it is on the slipper blade as the brits refer to it in the engine re-build found on mikes xs
     
    gggGary likes this.
  12. sweatybetty89

    sweatybetty89 XS650 Addict

    new chain is a must im just curious about the piece that has failed on the guide or is that part of the chain?
     
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  13. 5twins

    5twins XS650 Guru Top Contributor

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    The rear "guide" or "slipper" that the tensioner pushes into the chain to take up it's slack is usually OK. They rarely fail but can get badly worn if the chain is run too tight all the time. The front guide is the part that fails. It's an aluminum strip with a rubber layer bonded to it. The chain runs against it and it "guides" it so it runs straight. Now that they're so old, the rubber strip is coming unbonded and falling off. Then the chain runs against the guide's aluminum base, hence the aluminum bits you'll find in the oil.

    This is the front guide I replaced on my '78. The rubber hadn't fallen off yet but was pretty close to doing so. It was about 2/3 of the way unbonded .....

    [​IMG]
     
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  14. sweatybetty89

    sweatybetty89 XS650 Addict

    I am hopping that this could be the cause of the problems with my cam chain and where the shavings are coming from in my oil. It for sure looked to be aluminum i was seeing in that oil. I could where one of these waring out could cause some problems
     
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  15. X77S

    X77S Let's do this!

    So long as you're needing to change the cam chain, the tensioner is basically on the "build back up" process. It's not a really difficult job, just take your time.
     
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  16. Jan_P

    Jan_P XS650 Guru Top Contributor

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    Regarding Manual
    I have Clymer / Haynes /and on computer
    I think the books are Useful .. I have done a lot of work outdoors .. and is used to that since working construction
    Never use Rubber gloves .. So I have the book open somewhere close ..putting a wrench there to keep it open and during the work take a look at the pictures .And follow the text instructions
    Over the years the book looks a bit black ....
    The service manual have more INFO and having the computer near and oily hands is doable ..but not something I do.
    It happens that I wash the hands and look in the Service manual on the computer if uncertain. but rarely
     
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  17. gggGary

    gggGary On the road of life I'm a speed bump. XS650.com Supporter Top Contributor

    Gary Hoos, Hoos racing commissioned new cam guides built in Taiwan last year, so far all reports have been good.
     
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  18. sweatybetty89

    sweatybetty89 XS650 Addict

    I have looked in to the " build a better twin" writing online and was wondering if there is a place to get the parts needed for over hauling the engine in some kind of kit and if they are still making the parts listed in the b.a.b.t text? or if there are recommendations for some other parts that may be good to order just to start with. besides the obvious things like gaskets and new bolts so on and so fourth
     
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  19. 5twins

    5twins XS650 Guru Top Contributor

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    Yes, most of the stuff in that old article is N.L.A. There are no overhaul "kits" that I know of. The usual routine is, since it's quite a chore getting in there what with having to pull the engine out, replace everything that needs it. Normally that includes the gaskets, cam chain and front cam chain guide, and valve guide seals. Once apart you'll have to inspect the cylinders for wear and if still in spec, you can just replace the rings. If worn beyond the spec then an overbore will be needed. You usually hand lap all the valves back in and that cures any minor leaks. Also, those rubber/metal washers on the top 4 outside large acorn nuts need replacing. Most of us use copper washers there .....

    [​IMG]

    Those 4 outside studs drain oil from the topend back down to the bottom end so some sort of sealing washer is needed under their nut.
     
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  20. sweatybetty89

    sweatybetty89 XS650 Addict

    So got the bike in a space to work hoping to pull the motor today.
     

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