950 Cam chain tensioner jammed, bolts below 6mm

Discussion in 'Crazy-Awesome almost Dakar racers (950/990cc)' started by Jdeks, Jan 6, 2013.

  1. Jdeks

    Jdeks Accepting and supportive of everyones feelings.

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    Hi folks,

    Got an '04 950 Adv with 65000km on the clock, checking the cam chain tension as part of a service. Following the service manual and the HOW, except due to a lack of a 14mm allen key, I'm turning the engine over from the water pump wide with a socket on the balance shaft nut. However I'm turning it such that fron the generator side, the engine is turning counterclockwise as per the manual.

    I put the rear cylinder at TDC (all cam lobes pointing in, crosses against the gasket head), unscrewed and measured the tensioner bolt. It doesn't even touch the tensioner - Have to screw it in about a turn before it makes contact. Actual measurement from case to washer is about 5mm once screwed in to make contact with the tensioner. The tensioner itself is and long and springy as the new ones I have.

    Put the front cylinder at TDC (all lobes facing out, right?). Did the same thing, got the same results. Bolt needs to be screwed in to even contact the tensioner. Tensioner itself will not compress more than about a mm under finger pressure. Seems jammed.

    Have I screwed up/missed a procedure somewhere, or are both my cam chains really that clapped out? IN the few thousand k's before the service, I was noticing sporadically a much more pronounced start up rattle that wouldn't go away for a few minutes, unless I killed and restarted the engine.

    Thanks !
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  2. Peanuts

    Peanuts Long timer

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    You sound like you have the tensioner fully extended - which is correct

    You then screw in the tensioner cap (without the washer) until you feel it tighten against the tensioner.

    The distance from under the cap head to the cylinder has to be 6 to 11mm. If you have 5mm then the chain and tensioner rail ought to be replaced.

    That sticky tensioner will have caused your rattle, similar problem with the enduro bikes - that is cured by using a Dirt Tricks tensioner,
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  3. Jdeks

    Jdeks Accepting and supportive of everyones feelings.

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    Hey mate, thanks for the snappy reply :)

    The original plugs (short ones) are the ones in the bike - it's an 04 model. I have some shiny new long ones though, if need be. I put them in to test them, IIRC they give me about 7mm from base to washer....but I don;t know if just whacking them in is an adequate solution?

    Now, you say measure without the washer? But the service manual says "Measure the distance between the sealing washer and the cylinder head". If I screw in the plug far enough to just make contact with the tensioner, I'd say it's be *just* over 6mm from bolt head to cylinder.

    But I was under the impression that I shouldn't have to screw the bolt in AT ALL to get contact with the tensioner (if the chains are in spec).
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  4. Peanuts

    Peanuts Long timer

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    Yes, you are correct. Keep the washer on.

    I was sure the design of cap had changed, but cant find anything in the parts fische, so I guess they altered the fische for the early bikes so all models now fit the later caps.

    Therefore if you are in spec with the later cap I recon you are good to go....... lets see what others think!
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  5. Jdeks

    Jdeks Accepting and supportive of everyones feelings.

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    I'm not sure...I really don't like the idea of just 'replacing the ruler because it's not measuring what you'd like it to'. SOMEthing has worn, and while I'm this deep in engine bits, I think I'll go ahead and replace them anyway.

    Thanks for the help
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  6. Head2Wind

    Head2Wind MotorcycleMayhem

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    The later model caps were extended (longer) to increase the tension on the chains AND provide more effective stroke of the tensioners. EDIT: The fiche seems to not reflect this.... not sure if this is 100% accurate. I have a 06 ADV on the rack right now that I can measure the caps on to compare to your 04.

    If the new style caps get you within service limits again, then I would run them!

    It does not take much change in chain length or surface wear on the guides to make the early tensioning system go "out of spec". What I have seen comparing a new chain set to a old set is something to the tune of 1mm maybe 1.5mm difference in length is all.
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  7. Head2Wind

    Head2Wind MotorcycleMayhem

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    If you do decide to go with the full service replacement of timing drive systems, it means you should also replace both the front and rear guides for both cylinders, chains, tensioners.

    If its a early motor that has the early head nuts still I would also update them at the same time....

    Can be performed in the frame, however you will need a 14mm hex drive for turning the crankshaft to perform this work because the aux shaft will need to be removed to get the chains off/out.
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  8. Jdeks

    Jdeks Accepting and supportive of everyones feelings.

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    Hi H2W, thanks for chiming in.

    The later caps do indeed get me within spec - 7mm from washer to cylinder.

    Okay, I don't need to be told a third time not to spend money :evil. If you both think the longer caps are good enough, I'll just run them. I've read around a bit more and had a look at somediagrams and by the looks of things the early tensioner were just overly conservative in their tolerances.

    I'll let you know how loud the bang is when it grenades :p

    Thanks for the help.
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  9. multistraddler

    multistraddler Been here awhile

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    OK, first off sorry for resurrecting a 3 yr old thread, but enquiring minds and all that.

    How much longer were you able to go with this expensive, elongated bolts before having to replace the cam chains?

    I have the rear cylinder off my '04 w/ 35k miles, but before it came off I measured about 5.5mm between the washer and the cylinder. *Technically* I should replace the chain, but its not exactly a walk in the park to do that job. I'd be fine with procrastinating for a couple of years (procrastination is one of my core competencies.)

    If it weren't for the bother of having to remove so many bits and bobs to get at the chains (and the possibility of doing a shit job of reinstalling everything), I'd just do it. A set of chains is $120 and these damn bolts are 55 Euros for a pair + int'l shipping (uh...why the hell aren't these available in KTM largest market?)

    So, Jdeks, help me make up my feeble mind... :p
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  10. gearheadE30

    gearheadE30 Long timer

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    You've already got the rear cylinder off....it's probably not that much more work to just do the chains while you're in there. The longer caps will get your for awhile, but in the end, you still have chains that are stretched and will soon need replacement.

    I just replaced mine; they were right around 5mm on both cylinders at 75k miles on the engine. If you take your time, replacing the chains is a weekend job. It's really not that bad, and there's a great writeup on the HOW. There are some fiddly bits, but nothing too crazy.
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  11. multistraddler

    multistraddler Been here awhile

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    This is true. I've read through the HOW write ups. But, shouldn't I leave something to keep me busy next winter? ;)
    I figure I'll have the head covers off a year from now to do a valve clearance check and can do this job with the motor in the frame (mines out now) which may actually be easier.


    Sent from my iPad using Tapatalk
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  12. gearheadE30

    gearheadE30 Long timer

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    Yeah, I did mine in the frame and the only issue that caused was the upper timing chain guide retainer bolt on the front cylinder - had to remove the aluminum brace to get that out. It's not too bad in-engine.

    The longer tensioner caps would more than likely get you through until next winter if that's what you're after.
    #12