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Installing camshaft/chain timing UPDATE help, is it off ??

Discussion in 'FX Nytro General Talk' started by kimoajaj, Nov 28, 2012.

  1. kimoajaj

    kimoajaj Newbie

    Messages:
    292
    Location:
    Norway
    Hi guys!

    Today I installed the head on Dimebags engine and put the cams in and tried to set the timing correct.
    According to manual you first put the chain on the intake cam making sure that there is no slack on the chain and then put it over the exhaust cam. You then install the camshaft caps and eventually the chain tensioner goes in.

    This is what I am experiencing:

    Firstly its its difficult inticipate where the timing marks will be after you have tighten down the camshaft caps.
    Secondly, as I tighten the caps the chain skips on the crankshaft sprocket making the timing wrong on the intake camshaft.
    Tie wrapping the chain to the camshafts doesnt cure this problem.

    Are there any tricks for doing this?

    I remember back in the day when I had the cams out on a GSX-R 750, I think I had the other mechanic hold a steel rod against the chainguide (were the tensioner normally is) while I set the timing.
    Maybe this would be a good idea with the Nytro too? But I when you release the rod I figure the chain will jump.

    Do some guys partly install the chain tensioner while tightening down the camshfaft caps?

    I will make another attempt on Saturday, I only spent half an hour today fiddling with the timing so I figure I will make it when I have some more time, we`ll see.

    Like, there must be a reasonable normal way to do this, shouldnt have to be a magican.

    (oh well.. guess I`m just stupid)


    :)
  2. grizztracks

    grizztracks Tech Advisor Tech Advisor VIP Member

    Messages:
    1,542
    Location:
    Scio, NY
    Country:
    USA
    Snowmobile:
    FX Nytro RTX, RS Vector
    Why not tighten the caps without the chain on the gears and both cams and crank in the TDC position? With the cams in then install the chain and tensioner and use the valve cover to prevent the chain from jumping on the gears. I haven't done a Nytro yet but I've timed the Vector motor without to many issues.
  3. kimoajaj

    kimoajaj Newbie

    Messages:
    292
    Location:
    Norway
    Thanks for replying grizz!

    Yeah I thought of that but then I have to force both of the cams into position before putting the chain on. Well actually I guess that shouldnt really be a problem, it will probably be easier then putting the camshaft caps on/off 10times to get it right. Good idea!

    Maybe I can make a little tool at work that fits in the holes of the camshaft sprockets and then tie wrap the tool so that the the sprockets are in the correct position (or maybe have a friend help me hold them hehe).
    Then install the tensioner and the headcover and turn it over.

    After having turned the engine over a couple of times, shouldnt I be able to remove the headcover and turn the engine over when checking the valve clearances?
  4. grizztracks

    grizztracks Tech Advisor Tech Advisor VIP Member

    Messages:
    1,542
    Location:
    Scio, NY
    Country:
    USA
    Snowmobile:
    FX Nytro RTX, RS Vector
    I believe the Nytro cam chain tensioner is spring loaded and hydraulic so turning the engine without the cover in place may allow the chain to jump due to inadequate tensioner pressure. The small toothed gears and dual cam setup is ridicules. If you get any slop in the chain between the cams it'll jump the intake gear.
  5. kimoajaj

    kimoajaj Newbie

    Messages:
    292
    Location:
    Norway
    Hi guys!

    Today I went in the garage to time the Nytro engine.

    I found the best way was to do it as per manual.
    Today things went better, (for some reason?).

    But, no matter what I do I cannot get all the marks to line up 100% perfectly.

    When I line up the mark on the flywheel:
    [​IMG]

    The marks on the camshaft sprockets are like this:
    [​IMG]

    As you can see it seems like both of the sprockets could have been turned just a tad more.

    [​IMG]
    Here I have pushed the chain down with my finger.

    If I turn the crank so that the camshaft sprocket marks line up 100% correct, the crank mark will be off with about 5mm, actually just about the length of the line after the mark on the flywheel.

    I also tried to compensate for this by having the notch in the stator cover at the very beginning of the line before the mark itself. (about 5mm), but I still ended up with the exact same result.

    Like, I think it looks alittle wrong, but can it be a whole tooth wrong??? Any opinions?

    Will it ever be 100% correct ?


    As I have read in other posts, the chain did indeed skip tooths on the cam sprockets when turning it over if you didnt secure it with tie raps.
    Eventually I run out of tie raps so I need to get some more before I try again.

    However I did remove the tie raps and put the head cover on, I then turned the engine 10 turns and it didnt skip any teeths (as stated in other posts).

    Noone seems to really no wether the chain tensioner is hydraulic or if the oil is there only to prevent the springs from failing??

    When I turned the engine over the tensioner made this clicking sound (not from engaging more and more) but from being pushed in until the locking "ring" stopped it and then when the cams caused more slack in the chain the chain guides jumpes out together with the tensioner and makes a "click" sound. Firstly I thought this sound was the chain skipping on the crank but I was wrong.

    I also checked all the valve clearances and they were all OK! The only one being close to not OK was an exhaust valve that was just a little loose on 0,25mm but I had to use force to get 0,26mm in there so in my mind it checked out OK cause its better with too much clearance then too little, especially on the exhaust valves.


    Well, does anyone know if the timing marks should line up 100% perfectly correct ?

    Is my timing right or is it one tooth of on the crank??

    Dimebag is coming home soon so I better have it ready to be put back in the sled ! :)
  6. SRXSRULE2

    SRXSRULE2 Newbie

    Messages:
    267
    Location:
    Stouffville, Ontario
    I don't have a manual for this sled, but I have timed many overhead cam engines. If you could show me the procedure I could say yes or no. Obviously with the way the cover is designed, they don't want you to count teeth. Are there paint marks on the chain to line up with the cam gears? Or how do they want you to time it?
  7. kimoajaj

    kimoajaj Newbie

    Messages:
    292
    Location:
    Norway
    Hi there!


    There are no paint marks on chain/gears.
    Manual sais:

    -Put cams into head
    -Install chain firstly on the intake sprocket and make sure it is tight from the crank and up to the sprocket
    -Install chain on exhaust sprocket
    -Install camshaft caps and tighten down evenly
    -Install tensioner and turn the engine several turns and check that all the marks are ligned up.

    I have done this several times on motorcycles but never run into this problem. That said, on most bikes you have to loosen the camshaft caps and lift the cams up in the end in order to get the chain off the sprockets, so in other words the chains are shorter (!?).

    I know some people are running manual tensioners, I wish I had one that I could use when setting the timing so that I wount have to mess around with the ties. I have installed some manual tensioners in bikes but I have such great faith in Yamaha that I would never put one in my Nytro.
  8. SRXSRULE2

    SRXSRULE2 Newbie

    Messages:
    267
    Location:
    Stouffville, Ontario
    So do they give you reference marks for where the camshafts should be? Lets say a timing mark on the cam, and a mark on the cylinder head? If not, going by the manual you could just put the chain on anywhere with no slack and it would be totally wrong.

    On most engines, if they use the chain marks to set timing, they will never line up again. What I would do is set the timing where you think it should be. Put the tensioner in and install the valve cover so the chain doesn't jump. Turn the engine over by hand 2 times or 720 degrees. Remove the valve cover and see if the timing marks line up at the crank and the marks on the cylinder head for intake and exhaust cams. IF it looks good and you feel no resistance when turning the engine over, I'd say you're good to go.
  9. kimoajaj

    kimoajaj Newbie

    Messages:
    292
    Location:
    Norway
    Just look at the photos, you can see the marks, there is a line on both sides of the sprockets, these are suppost to be flush with the head (where the head cover rests). You can also see the mark on the flywheel that the notch in the stator cover is suppost to be pointing at. (in the photo above).

    I need to know wether the slack in the chain (that would be picked up by the hydraulic tensioner (if it is hydraulic) is enough to make it seem like it is just alittle off or if it is one tooth off on the crank.
  10. SRXSRULE2

    SRXSRULE2 Newbie

    Messages:
    267
    Location:
    Stouffville, Ontario
    I see what you mean now. To say that you are off one tooth at the crank doesn't really matter because the chain could be on anywhere as long as the timing marks are lined up. The tensioner is on the back side/ exhaust side correct? If so, this is where you would want the slack to be. You always want to be tight on the side that pulls. So looking at the engine, it rotates counter clockwise, meaning its going to pull the chain down from the intake cam. If you have no slack here, and no slack between the two cams you are good.

    So judging by your pictures what I would do is line up the crank and keep it there. Line up the intake cam and pull all of the slack from the chain and put the chain on the intake cam, then with pull the slack between the cams and place chain on exhaust cam, then install the tensioner and check it.
  11. SRXSRULE2

    SRXSRULE2 Newbie

    Messages:
    267
    Location:
    Stouffville, Ontario
    My apologies, I just looked at parts manual and I see the cams gears are on the right side of sled. So Its the same principal but backwards.
  12. grizztracks

    grizztracks Tech Advisor Tech Advisor VIP Member

    Messages:
    1,542
    Location:
    Scio, NY
    Country:
    USA
    Snowmobile:
    FX Nytro RTX, RS Vector
    Does the stator have a single "I" and also a "II" mark? On the vector the manual say align the "I" mark but you actual align the dual "II" to get it timed properly.
  13. Gauthier

    Gauthier Newbie

    Messages:
    15
    Location:
    Canada
    Do you put headshim on it ?
  14. 1975FA

    1975FA Veteran

    Messages:
    209
    Location:
    Lowville, NY
    Is your timing chain new or used? How stretched is it. When its off the engine how far will it bend sideways?
  15. kimoajaj

    kimoajaj Newbie

    Messages:
    292
    Location:
    Norway
    Hi !

    Grizztracks, it only has a singe I, it looks like this:

    I I--I

    I havent installed a headshim, he is running the 180kit on the sled.

    The engine had 12.000kms on the clocks before tear down. So basically it has some milage but when thinking of the fact that these chains last 60-100.000kms on bikes, I`m not worried about re-using it.

    Today I called the mechanic at the local Yamaha shop (I know he is a really good guy cause I have worked there for a year). He said that the notch in the stator cover should be on the last I on the flywheel and not between them like I thought. He also said that if the chain was stretched a little it would affect the timing and that the slack in the chain from the chain tensioner not having oil pressure also could affect it a little.

    However he said that if the marks on the cam sprockets were close to correct, like 1-2mm higher or lower it couldnt be wrong cause if it was a whole tooth wrong the difference would be much more.
    Also, the holes in the cams that are suppost to line up with the camshaft caps, were spot on.

    So he said that I was good to go and shouldnt worry. He also confirmed that the tensioner is indeed hydraulic, there seems to be some confusion about the tensioner being hydraulic or not but now we know! He said that he was nervous on the first startup but he had never experienced a skipping chain.

    Wellwell will keep you posted!

    Today I finished the build and the engine is now lying in my car waiting for dimebag to come home:)

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