6th Gen Cam Chain Questions

Discussion in 'Mechanics Garage' started by Aced It, Oct 15, 2019.

  1. Aced It

    Aced It New Member

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    My 6th gen VFR has manual cam chain tensioners. The rear one has been slighting seeping oil since I got her a couple months ago. I chose to back the bolt out and replace the o-ring using some leak sealant to hopefully prevent this further. After turning it back inward which I thought was the correct amount of turns, I started the bike to listen and set the final turns. The engine sounded like it was missing a bit and there seemed to be a lot of cam chain noise. I shut it down, removed the crankshaft access cover and proceeded to turn the crank by hand, not noticing anything but figured this would help a bit in fine-tuning the manual tensioner a bit before cranking again. I have a young friend who was present and when he started turning the crank (still by hand) it got to a point where it seemed locked. He forced it, not extreme but enough now where the crank feels locked in both directions. I have not checked to see if it's locked at TDC in both directions yet, but will tonight hopefully. I did pull the lower engine cover off to get a visual on the cam chains. When I rotate it backwards a bit, the rear cam chain slacks a bit (toward the front), but rotate forward and it tightens up ... I don't know if that's normal. Could the cam chain have jumped a tooth or two by this procedure? I don't notice anything broken. Maybe I didn't have the tensioner far enough in and there was too much slack before I started the engine? Would there be enough slack to have caused the chain to jump teeth? Not starting the bike until I get it sorted. May pull the valve covers tonight for further investigation. Anyone else experience this? Opinions matter; experience preferred. :)
     
  2. Terry Smith

    Terry Smith Member

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    With a tensioner backed right off I'm sure there can be enough slack to jump a tooth but I'm surprised that would happen unless the crank was moved.

    The only way to check your cam timing is to pull the cam cover off (and the back one is the easy one) and check the timing of the crank vs the marks on the cam spockets. From the manual, with the 3T mark aligned on the crank, the index lines on the sprockets should point out and align with the camcover surface.

    I fitted manual CCTs to my VTR1000F and when I did that, the instruction was to set the camchain slack between the sprockets to 5-7mm; with you cam cover off you can do this on your VFR. cams.png
     
  3. Aced It

    Aced It New Member

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    Thanks Terry. Started the minor tear-down this evening but didn't get far. Just enough time to siphon my full tank of gas out and make-shift a support for the tank instead of flipping it on it's side and/or removing the fuel lines. The weight of the fuel was making the tank unstable in the upright position after removing the rear bolts. So I doubled up some zip-ties and used a jack handle to hold up the tank. I have a manual, which states, "Place the fuel tank upside down and remove the fuel tank from the frame without disconnecting the fuel tank. hoses. Be careful not to damage the fuel tank." ... Weird, and no. Thought about just disconnecting the fuel lines, but figured my make-shift will work for now. Then I ordered a new cover gasket. ... Funny how a seemingly simple project turns ugly real fast, no doubt due to my lack of sleep as of late. LOL

    20191015_173646.jpg 20191015_173628.jpg
     
  4. Aced It

    Aced It New Member

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    Got the rear cylinder head cover off last night. I only get about 30 minutes to an hour each evening until the weekend comes; steady as she goes. The cam chain had jumped. I saw no evidence of anything broken, but I'll put my bore-scope down the spark plug hole and examine the top of the pistons just to see if any contact was made. If I have to, I'll remove the throttle bodies and exhaust to further look for bent valves. This 800 being an interference engine, I'm hopeful nothing bent as I said there were no tapping/knocking noises other than the chain when it was started with the tensioner partially adjusted, and afterward the crank was only turned by hand with the chain loose which could have been binding (hopeful).

    Any advice is appreciated with further diagnosis and reassembly/timing.
     
  5. Aced It

    Aced It New Member

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    Well, damn HF bore-scope was too large to get into the spark-plug hole.

    A few things to ask:

    It is my understanding per the manual that you have to remove the front cylinder head cover in order to line up the indicators to assist with aligning the rear. Is that correct? Is there any other known method before I tear into the front?

    On an unrelated matter, well somewhat, I also noticed that the front cylinder still has the (what appears to be) original cam chain tensioner. At nearly 70K miles, what's the opinion on whether I should replace that? Should I replace it with a manual unit to match the rear? Or should I replace both with new OEM tensioners?

    20191017_164648.jpg
     
  6. Terry Smith

    Terry Smith Member

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    As long as you don't mess with the crank, you don't need to take off the front cover as the two banks are nearly in correct phase right now, so you just need to correct the rear timing and you're done.

    You can infer the valve condition by checking the valve clearances; if the valve stem has been slightly bent the clearance will jump up a lot. If the clearances are are all normal odds are you haven't caused any damage. You could also check the compression once the timing is reset.
     
  7. Aced It

    Aced It New Member

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    Well crap. I messed with the crank.

    Sent from my LGMP260 using Tapatalk
     
  8. Terry Smith

    Terry Smith Member

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    Still not impossible to do with the camcover on as long as you can figure out when the front cylinders are at TDC on compression. If you leave one plug in the front head you can work that out from the compression you feel as you turn the engine over.
     
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  9. Aced It

    Aced It New Member

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    Thanks Terry. I really do appreciate your advice. Weekend is coming up and I'll have more time to dig in.
     
  10. Aced It

    Aced It New Member

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    I found TDC on the compression side for cylinder #4 in front. How many turns of the crank to the compression stroke TDC for cylinder #3? Is it a 270 degree turn to the 3T mark?

    And maybe it's me (which it usually is). I'm thoroughly confused in following the service manual:

    First, I cannot make out any of the cam sprocket markings or "index lines" in the photos, so I cannot line up the rear cams properly. Need ... help ... please. Any pics or better definition of exactly what lines, triangles and/or letters would be most appreciated!

    Secondly, under the section REAR CAMSHAFT INSTALLATION (p. 8-42), subsection IF ONLY THE REAR CYLINDER CAMSHAFT WAS REMOVED (p. 8-46), shouldn't the last paragraph on page 8-46 state to install the "rear" cylinder camshafts with the index ....." (lower left in pic below). The same exact wording is used on the following page 8-47 for the instance of IF ONLY THE "FRONT" CYLINDER CAMSHAFT WAS REMOVED."

    So there it is. My daily confusion.

    20191019_155327.jpg
     
  11. Terry Smith

    Terry Smith Member

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    The firing order is shown at the start of the manual. If you start at TDC#4 there are 90 degrees to #1 then 180 degrees to #3 so 270 degrees in total.

    Remember that the cams run at half crank speed so they will only move 135 degrees when you are doing this.

    There is a comment that when #4 is at TDC the rear cam sprockets should line up with triangular marks aligning to the gasket surface at the outside.

    upload_2019-10-21_10-33-49.png
     

    Attached Files:

  12. Aced It

    Aced It New Member

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    Thanks again Terry, I just got your reply. I guess it's you and me having a conversation, lol! But I truly appreciate it.

    I've managed to get everything lined up and it appears that nothing is damaged, at least visually and rotationally. What really frustrates me is the lining up of the index lines. They never seem to get absolutely on the same plane as the head. Each time, I rotate the crank a few times bringing #3 back to TDC at compression. The lines are either just below or if I rotate the gears a tooth they are just above. Maybe it's my OCD, but see the pics.

    Cam lobes lined up:
    20191020_133034.jpg

    This pic shows the lines just below the cylinder head top plane...
    20191020_160944.jpg

    And of course, I somehow didn't capture the pic with the lines just above. Anyway, thoughts/insight most welcome. Thanks again.
     
  13. Terry Smith

    Terry Smith Member

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    My experience is not with the VFR but my VTR1000F. At 70,000km I installed manual CCTs and after installation I checked the timing and it was maybe 1/2 a tooth out between the crank mark and the cam marks (and of course I never checked it with the auto CCTs). Now that is not strictly possible so I put it down to either wear on the chain guides or stretch in the chain, either way it was what it was and I knew moving the cam relative to the crank wasn't going to improve it. You can see the F timing mark below when the cams were dead on.
    upload_2019-10-21_15-50-28.png
    And the image below is the front head with the crank timing dead on:
    upload_2019-10-21_15-52-37.png
    The VTR runs great so I just chalked that up to experience and age.
     
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  14. Aced It

    Aced It New Member

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    I greatly appreciate again your response. Looking to wrap this up sometime this week. I'll keep you posted.
     
  15. Aced It

    Aced It New Member

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    Here's better pics of the cam gear index lines not lining up with the crankshaft index line. I'm pretty much on target with the camera angle(s), but let's count for a little human error for the sake of argument. Let me know what you think:

    Cam gear index lines aligned to each other and cylinder head:
    20191022_181834.jpg 20191022_181850.jpg 20191022_181943_HDR.jpg
    Crankshaft index line aligned with cover notch:
    20191022_181547.jpg 20191022_181505.jpg 20191022_181049.jpg
     
  16. Terry Smith

    Terry Smith Member

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    I went high-tech and put my plastic protractor up against the screen. The crank looks like it is just less than 5 degrees off when the cams are dead-on. The cam sprockets look like they have 40 teeth so the crank will have 20 teeth, so there must be 18 degrees of crank rotation per tooth (360/20). Therefore you must have the crank and cams at their closest to correct phasing i.e. as good as you're going to get. Is this with the camchain tensioned properly? I wondered whether that would pull the parts into better phasing.
     
  17. Aced It

    Aced It New Member

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    Protractor on the screen? Lol, hopefully my camera shots were close to on center. And yes, I did tighten the tensioner (manual unit) but only by sight and feel. I also took the pics after a few rotations of the crank; I recall 4 times.

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  18. Terry Smith

    Terry Smith Member

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    If the engine is now turning over freely then I'd say you're done and should button the camcover back on and press the start button...
     
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  19. Aced It

    Aced It New Member

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    Since I have it opened up, I've gone ahead and ordered new timing chains. After trying to get it all lined up, I think they might be a bit worn. I'm in no hurry, and she's got 70,000 miles, so why not. Also got a manual tensioner for the forward cylinder too.

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  20. Darth Vader

    Darth Vader New Member

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    There was a magazine article i read about a bloke who was doing up a big single off roader and he had the same problem of the timing marks being out by just a bit. Long story short his cam chain had stretched. New one solved the problem.
     
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