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Valve clearance - lining up the marks

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geewhizz
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Valve clearance - lining up the marks

Post by geewhizz on Mon 10 Dec 2018, 11:34 pm

hello all, I am looking for guidance or hopefully reassurance regarding my observation while attempting to line up the marks in the viewing port and the markings on the sprockets of the cams. I had to wind the engine on a bit from absolute alignment in the sight glass to get the marking on the sprocket to line up. Would this be due to the cam chain stretching over time (50k miles) or could the timing be out slightly? Bear in mind the engine has been untouched for at least 25k miles and runs well.

When taking the measurements I went with the marking on the sprockets over the marking in the sight port (there was about 5mm or so difference, so the sight glass marking was almost out of sight)


And so long as above doesn’t give me problems, I’m looking for some shims - anyone got a supply for swaps? 

Cheers, G
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skyerae
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Re: Valve clearance - lining up the marks

Post by skyerae on Tue 11 Dec 2018, 6:41 am

Have a look at the Shim Exchange in the Workshop section of this fine forum - just remember to return the leftover shims to the chap who runs it though. Can't help you with the timing marks though, sorry.
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geewhizz
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Re: Valve clearance - lining up the marks

Post by geewhizz on Tue 11 Dec 2018, 9:11 pm

Thanks skyerae, Ive posted on the shim thread, hopefully a member of shim club will sort me out. 

Best G
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geewhizz
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Re: Valve clearance - lining up the marks

Post by geewhizz on Tue 11 Dec 2018, 10:01 pm

Wait... did I just break the first rule of shim club ?
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Jameshambleton
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Re: Valve clearance - lining up the marks

Post by Jameshambleton on Wed 12 Dec 2018, 2:09 pm

Take the cam chain off the cams.

Set the bottom marker into position, then with my cams I had to face them both slightly down on the timing marks.
So they looked like this.


Make sure the chain is already fitted on the crank.

Fit the cam chain on the exhaust cam first and then >>attempt<< to get the inlet cam in position.

Make sure you fit the chain along the teeth of the inlet cam and take into account the rotation you'll need for getting it in.

After you've fitted the cams in the correct positions, hold your hand to keep the tension on the chain so it doesn't jump a tooth.

Then fit the cam chain tensioner whilst retracted and SLOWLY unravel the spring so that it doesn't once again make the chain jump a tooth.

Turn the engine over BY HAND (with the sparkplugs removed) to ensure the valves clear the pistons. You will know if they hit but don't ffs use the starter motor or you will bugger the valves.

If they hit, go back to the start of this post and try again. If you want help over the phone and I'm not answering pm's AndyC and wornsprockets have my number
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geewhizz
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Re: Valve clearance - lining up the marks

Post by geewhizz on Thu 13 Dec 2018, 5:29 pm

Cheers James, thanks for taking the time to write down your thoughts and the diagrams really helpful too. Top man
 
I’m still in in two minds about re-aligning the flywheel and cam sprockets or just leaving it as is because the engine seems to run really well.
 
I’ve got a few more questions, hopefully with greater clarity, keen to hear ideas from anyone in the know….
 
 
·     Is it essential that the marking on the flywheel line up EXACTLY along with the marking on the cam sprocket? I’ve read on some car forums about the markings not lining up.
·     Are the alignment markings on the flywheel of more importance than the marking on the cam sprockets?
·     On my machine, the marking on the flywheel need to be wound round maybe 5-10 mm counter-clockwise to get the marking on the sprocket to line up with the engine block. Is this normal? Is it likely that the timing chain has skipped a tooth? 
·     Would the engine be noticeably out of sink if it had skipped a tooth?
 

Thanks for reading, G
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Jameshambleton
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Re: Valve clearance - lining up the marks

Post by Jameshambleton on Fri 14 Dec 2018, 3:51 pm

You want to have the makings as close as you can to stock settings. All the markings are as equal to eachother on the timing. As for normality you need to remember that you've got 3 sprockets and 1 chain so there will be some wear on all parties so so the timings won't be exactly spot on but you want them. As close as you can
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eternally_troubled
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Re: Valve clearance - lining up the marks

Post by eternally_troubled on Sat 15 Dec 2018, 5:29 pm

@geewhizz wrote:Cheers James, thanks for taking the time to write down your thoughts and the diagrams really helpful too. Top man
 
I’m still in in two minds about re-aligning the flywheel and cam sprockets or just leaving it as is because the engine seems to run really well.
 
I’ve got a few more questions, hopefully with greater clarity, keen to hear ideas from anyone in the know….
 
 
·     Is it essential that the marking on the flywheel line up EXACTLY along with the marking on the cam sprocket? I’ve read on some car forums about the markings not lining up.
·     Are the alignment markings on the flywheel of more importance than the marking on the cam sprockets?
·     On my machine, the marking on the flywheel need to be wound round maybe 5-10 mm counter-clockwise to get the marking on the sprocket to line up with the engine block. Is this normal? Is it likely that the timing chain has skipped a tooth? 
·     Would the engine be noticeably out of sink if it had skipped a tooth?
 

Thanks for reading, G

Well, I probably can't rightly answer those questions, but:

* Once you've lined it all up as best you can and re-applied the tensioner, if you can turn the engine by hand and the valves manage to avoid the pistons then it is at least safe to continue (do a good few revolutions to make sure).

* Assuming you are happy with the above, put everything back together and try it out.  If it runs well (well, at least as well as before!) then you got it right.


I suspect that, as James has said, there is some chain wear which makes things not quite line up the way they once did.

Did you note how far 'out' the marks were before you started?

Sorry not to be more use...
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geewhizz
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Re: Valve clearance - lining up the marks

Post by geewhizz on Mon 17 Dec 2018, 2:02 pm

Thank you both for responding. I'll endeavour to re-align markings and make a call if it looks better, otherwise I'll aim to put it back as I found as it wasn't out by very much.

Will post results when I get the job done over the xmas holidays.

Cheers, Geewhizz
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eternally_troubled
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Re: Valve clearance - lining up the marks

Post by eternally_troubled on Fri 21 Dec 2018, 8:29 pm

Best of luck.  I really hope it goes ok...
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geewhizz
the 900
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Re: Valve clearance - lining up the marks

Post by geewhizz on Sat 29 Dec 2018, 7:38 pm

Went with the original marking as by my guesstimating, it would be slightly more out of line if I moved the inlet cam round one tooth. So basically no change, other than the shims are all in tolerance which is pleasing, just waiting on the battery’s to charge and I’ll fire it up (have turned it over quite a few times by hand and by battery without sparks and nothing seems to foul. Touch wood.

On another note regarding checking valve clearances, in particular moving from checking cylinder 1 to 2, Haynes says turn the crank shaft anti clockwise 180deg to get the ‘EX’ exhaust timing marking up to 12 o’clock. But by my count it takes about 360+180deg to achieve this? Typo or my bad spannering? G

G
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geewhizz
the 900
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Re: Valve clearance - lining up the marks

Post by geewhizz on Sun 30 Dec 2018, 9:39 am

She lives. Got it fired up this morning and its got a nice gentle ticking sound from the front end. Not sure I’ll get the chance to ride it for a while but at least it seems very happy ticking over. 

Thanks for everyone’s help on the forum once again. Very Happy

G
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eternally_troubled
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Re: Valve clearance - lining up the marks

Post by eternally_troubled on Sun 30 Dec 2018, 6:44 pm

Glad to hear it all went OK.

I can remember the Haynes being in some way incorrect about how much turning was required, but I haven't done this job for a few years so the specifics escape me.  Missing out the odd 360 degrees isn't exactly difficult, so I wouldn't be surprised if it is slightly wrong...

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