How To Do 'camshaft Timing' Service Item On A Water-cooled Twin?

Discussion in 'Technical Help' started by brown mouse, Feb 14, 2022.

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  1. brown mouse

    brown mouse First Class Member

    Sep 15, 2018
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    My 1200 twin engine is coming up to 40k miles so am planning on doing it's second engine service. The service schedule in my owners manual has an item that just says 'camshaft timing' but I see not mention of this in the routine servicing chapter of the Haynes manual, so am wondering how to do this?

    From what I can see, the only timing adjustment is in rotating the sprocket on the camshaft and aligning this correctly in mentioned in the chapter about taking engine apart. This involves putting a locking pin into the bottom end gubbins and the hole for that is hidden behind the alternator cover. I'm guessing this is what I'll need to do, but am reluctant to remove the alternator cover as I had a leak from there not long after I got the bike, and it seems very fiddly to get off and on, with the cables and grommet, and there's no gasket for sealing from what I can determine.

    There are a few videos of youtube of people doing valve clearance checks on these engines, and they comment that you don't need to take alternator cover off like Triumph say. What I'm guessing is that they aren't bothering to check camshaft timing on their services, just the clearances.
     
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  2. XCaTel

    XCaTel Senior Member

    Feb 22, 2018
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    The camshaft timing is just taking care of the fact that the cam chain has stretched over time. It is a once every 20k miles on my Tiger 1200 too. Over time my Tiger has got a little more vibey and I am hoping this camshaft adjustment might smooth it out a little. I do think it is worth addressing.
     
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  3. brown mouse

    brown mouse First Class Member

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    Reading the Haynes manual more carefully and looking at parts diagrams, the alternator cover does have a gasket, and there's a couple of o-rings needed too. (More parts to buy.) Interesting that the engine service kit for the bike has cam cover gaskets but not alternator cover ones.

    The outlined process for setting the timing also involves 200 quid of specialist tools to temporarily replace the chain tensioner with something precise. Though I've found someone who seems to know what he's doing that didn't do anything specific with the chain tensioning. This is a good video about replacing a camshaft on a water-cooled twin...

     
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  4. joe mc donald

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    Brown Mouse
    Yes i think i would have been the same and leave it to someone who knows the job.
    Joe
     
  5. brown mouse

    brown mouse First Class Member

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    Thing is, to check the timing requires most of the dismantling required to do shims, and probably wants the oil draining too. So, that would mean it would make sense just to get someone else to do the whole engine service. And there's the perennial problem of finding someone you trust. I'm not sure I trust the dealers, and I'm loathed to pay 600 quid or so for a job I'm not sure has been done correct.

    I'm inclined to do it myself, or at least take the alternator cover off and check what the timing is by eye, just making sure the chain is taught by hand. (I really can't see a professional motorcycle mechanic doing any different. They're not all going to have, or bother with, triumphs chain tensioner gadget.)

    Would be happiest if I could see what Triumphs official instructions are for the service. There was a paid for website to get access I seem to remember, but that looked daunting in itself last time I looked.
     
  6. Linx

    Linx Well-Known Member

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  7. brown mouse

    brown mouse First Class Member

    Sep 15, 2018
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    Thanks, I actually did that before seeing your post :)

    The official instructions don't shed any more light on the matter that the Haynes manual. There are no instructions for the service item 'Camshaft timing check', just instructions for setting timing when fitting the camshaft. Interestingly the valve clearance check says to use the rear wheel to turn engine, nothing about removing alternator cover.

    And the official instructions to remove alternator cover is to dismantle half the bike. (That'll be to free the cables hidden behind everything else). Which obviously isn't something to do just to get access to the hole for the crank case locking pin.

    Guess I'll will just be doing what 'feels right'.

    First thing I've got to do though is burn off that full tank of petrol so it's easier to manage when I take it off the bike. ;)
     
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  8. brown mouse

    brown mouse First Class Member

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    #8 brown mouse, Feb 18, 2022
    Last edited: Feb 18, 2022
    So. The procedure for fitting the cam-chain tensioner says near the end (paraphrasing a little)...

    Rotate engine through 4 full revolutions, and reset cylinder number 1 to TDC. Ensure the timing tool pin aligns with hole in the crank case.​

    Next

    Check the camshaft timing marks are correctly aligned​

    So, the timing marks on the camshaft are for TDC and I can get that by sticking a wooden dowel or something through the spark plug :) Or perhaps a proper dial gauge as turning the engine by back wheel it difficult and I can't be up at the engine end at same time.
     
  9. Pegscraper

    Pegscraper Elite Member

    Jun 12, 2020
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    Having read through this thread I will also be checking the timing myself, assuming I keep the bike long enough for it to be necessary. I find it strange that it is deemed necesary at 20k miles due to possible wear and makes me wonder what the life expectancy is for these engines. It's not as if they're a complex, highly tuned, high revving unit (the Classic twins that is). Even with the valve timing check/adjustment procedure, they're still much easier to work on then many big IL4's I've come across.
     
  10. brown mouse

    brown mouse First Class Member

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    #10 brown mouse, Feb 18, 2022
    Last edited: Feb 18, 2022
    I'm doing my bikes 2nd 20k service (at 36k so I'm not doing it when the weather's good) though timing is specified at every 20k.

    Experimenting around, TDC doesn't seem to occur at camshaft timing marks, though chain tension could have something to do that, as there is definitely sloppiness between what I feel from a pencil touching the piston crown and what I'm seeing with the camshaft . Think I'm going to have to bite the bullet and do it by the book, and also splash out on Triumph's chain tensioner tool. Though it did occur to me that with a rocker or two removed they'll be no backlash from the valve springs and you could keep the chain taught by hand. Presumably as the TEC Bike Parts guy is doing when he's fitting the new camshaft (though he doesn't say that)
     
  11. Pegscraper

    Pegscraper Elite Member

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    Irrespective of any markinigs on the crank or cams etc, to find true TDC as you describe, with a pencil or other probe, you really need a degree wheel. The crank will move through several degrees at TDC (and BDC) without any vertical movement of the piston which my be the 'slop" you mention, if I've read your post correctly. I made a probe out of an old spark plug for an engine I worked on years ago for precise setting of TDC. If the rockers are out then, as you say, there will be no tension on the cam from the valve springs so all you have to do really is keep some pressure on the tensioner blade with a short piece of dowell etc, plus, there's no chance of valvetrain damage with the rockers out if you get the timing wrong.
    I feel sure the job is doable without the special tools.
     
  12. brown mouse

    brown mouse First Class Member

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    Thanks for the encouragement. And yes, cam-chain tensioning tool seems redundant if rockers are off and cam can move freely.
     
  13. Tom Swift

    Tom Swift Member

    Sep 24, 2021
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    There's usually some advanced valve timing built into OEM cams to move the TQ curve down the RPM scale. As the drive parts wear, the camshaft looses some of that advance. If no advance is designed into the camshaft, timing would immediately go retarded as parts wear. Retarding the timing produces more HP but there's also more risk of the piston hitting the exhaust valves if they float.

    My guess is the valve timing is around 5 crank degrees advanced and parts would never wear enough to have interference problems by getting too retarded from wear. OTOH, without actually measuring to know for sure if there's some built in advance, checking it according to the manual is the best way to go.
     
  14. brown mouse

    brown mouse First Class Member

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    #14 brown mouse, Feb 19, 2022
    Last edited: Feb 19, 2022
    I'm unsure from which point of view your advance and retard terms refer too, e.g. retard = valves after crank or crank after valve?

    The service manual quotes, for 1mm valve lift, the inlet valve opens 5 degrees after TDC, and exhaust closes 4 degrees before TDC.

    So, if the camchain wears, these valves will be getting to these position later. I.e. exhauste closing closer to TDC, and inlet further after TDC.
     
  15. Pegscraper

    Pegscraper Elite Member

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    #15 Pegscraper, Feb 19, 2022
    Last edited: Feb 19, 2022
    Valve timing figures always refer to the position of the cam in relation to the crank. Advance means open early and retard means open later.
    So, with the figures you've given, the inlet opening 3 deg ATDC would be 2 deg advanced and opening 7deg ATDC would be 2 deg retarded. With a SOHC, obviously you can't alter inlet timing separately to exhaust.
    The point Tom Swift was making was the cam design will have some "extra" advance to compensate for the gradual wear of valve train components. It'll not be anything like 5 deg though IMO.
     
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  16. brown mouse

    brown mouse First Class Member

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    Thanks. That's what I was thinking, but wanted to make sure. Wish me luck, am about to take alternator cover off...
     
  17. brown mouse

    brown mouse First Class Member

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    #17 brown mouse, Feb 19, 2022
    Last edited: Feb 19, 2022
    So, using a ruler on my screen, and the small angle sine approximation, my timing is out by 1.3 degrees. I have the official triumph timing pin locking the bottom end and there is a tiny amount of slack there, I don't have the tool to lock that slot in the camshaft, needed if I were to adjust things, but no doubt there's a tiny amount of slack there too. So I reckon, if I were to try and fix the timing I'd be hard pushed to get it completely accurate without constant trial-and-error. Basically, I'm thinking of calling this good enough for now, and I now have a baseline for the next service.

    BTW, I didn't do anything special for the cam-chain tension, I found there is almost no discernable slack in it, about the same as in the lock pin. I also arrived at the timing reference from the correct direction, so the chain was pulling in the direction it does when running, so chain should have been taught. I was doing this without the rockers on, so didn't have valve springs pushing back either.

    0.jpg


    timing-2.jpg
     
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  18. Pegscraper

    Pegscraper Elite Member

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    1.3 deg is bugger all and will make no difference on these engines IMO. Besides, to get 100% accuracy you really need to find true TDC which means using a degree wheel and not just rely on timing marks due to production tolerances.
     
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  19. brown mouse

    brown mouse First Class Member

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    Well, I bet with modern production techniques and CNC machines those timing holes and other parts will be damn accurate. But I'm not sweating about it. Taking a break to rehydrate ;) after scraping old gasket off, from some pretty inaccessible spots. That alternator has damn sharp edges too, must remember to clean up the blood...o_O
     
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  20. Pegscraper

    Pegscraper Elite Member

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    Old gasket removal, the bain of any servicing job. Is the light playing tricks or is that a crack in the crankcase there behind the alternator? .........:eek:
     

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