Most motorcycle problems are caused by the nut that connects the handlebars to the saddle.

Timing marks

wrighty
wrighty
Four's a...something...
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Post by wrighty on Fri 22 Mar 2019, 12:25 pm

I'm sure this has raised its head before but when checking valve clearances if the "T" mark is exactly on its marks then the two camshaft marks are a bit off, and if I get the two camshaft marks correctly in line then the "T" mark is nowhere near. I don't believe its far enough off to indicate that the camchain is a tooth out, but when I measure clearances which is the most critical to have exactly on the mark? At the moment it looks like all clearances are too small so I guess some new shims are required. 
 Bearing in mind the bike has stood for 6-7 years and that the previous owner had even less nouse than me I'd be willing to bet clearances have never been checked before. (29k miles).
hh_12345
hh_12345
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Post by hh_12345 on Fri 22 Mar 2019, 1:42 pm

There are several topics on the forum about this containing some good info and pictures.

I recently went through the same while adjusting the valve clearances. The first time I adjusted the chain the marks seemed a bit off, so I did it again. They did not match perfectly again but I left them as they were, so I think it's about doing it several times until you are sure you can not do it better.

I think that for measuring you have to watch for the camshaft marks as indicated in the manual.
wrighty
wrighty
Four's a...something...
Four's a...something...

Posts : 154
Location : Market Deeping Lincs

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Post by wrighty on Fri 22 Mar 2019, 3:51 pm

Cheers hh, that was my thought.
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sullivj
the 900
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Post by sullivj on Fri 22 Mar 2019, 6:45 pm

Don't forget The Shim Exchange if you need any
wrighty
wrighty
Four's a...something...
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Posts : 154
Location : Market Deeping Lincs

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Post by wrighty on Fri 22 Mar 2019, 9:29 pm

Yes mate I'll be in touch when ive got required sizes.
ANDYC
ANDYC
the 900
the 900

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Post by ANDYC on Fri 22 Mar 2019, 10:36 pm

If I'm just checking the valve clearances I just point the sharp bits of the cams 180 degrees from the valve to make sure that I'm not getting a false (small) reading from the ramp part of the lobe.
wrighty
wrighty
Four's a...something...
Four's a...something...

Posts : 154
Location : Market Deeping Lincs

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Post by wrighty on Sat 23 Mar 2019, 8:52 am

Thats interesting Andy, so what is the relevance of the 'in' and 'ex' marks lining up with the top of the head? As it happens it makes no difference on mine, although I'm kind of estimating the actual gap as one feeler wont go in at all and the next one down is a very easy fit, so im taking the mid point as the actual gap. For example inlet should be between 0.14 and 0.18 (midpoint 0.16) but 0.15 wont go in at all and 0.1 is too easy so i'm estimating 0.125 ( a difference of 0.035 from the midpoint).
   If I reduce shim size accordingly it should bring it within spec. Or?
ANDYC
ANDYC
the 900
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Post by ANDYC on Sat 23 Mar 2019, 9:23 am

The timing marks are only really relevant when you have had the cams out to change the shims or other reason.  Actually checking the clearances I find them unnecessary.
Unless you have a honda feeler gauge it's difficult to find the exact size but as long as you are close it won't matter. Losing a couple of hundredths of a millimetre of valve lift is not going to make a great deal of difference in the bigger picture. Recheck the clearances with the lobes pointing away from the valve and you may find that the readings are within specs anyway.
wrighty
wrighty
Four's a...something...
Four's a...something...

Posts : 154
Location : Market Deeping Lincs

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Post by wrighty on Sat 23 Mar 2019, 9:37 am

Yeah thanks Andy ive done that and it makes no difference with my halfords feelers. I'm on family duties today but hopefully tomorrow I'll get camshafts off and work out what shims I need. Screw and locknut on my old air cooled sohc cb550 was such a quick and easy job in comparison. My next project will be aircooled twin of some kind and next time I'll get the engine running right first before I do the cosmetics. Enthusiasm got the better of me this time now its frustrating to have the bike looking good and ready for mot but running so bad. Valves first then carbs, should have it sorted. By the way my manual cct arrived the other day so that will go in when shims are done.
ANDYC
ANDYC
the 900
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Post by ANDYC on Sat 23 Mar 2019, 9:54 am

Screw and locknut are easier but you have to do them far more frequently.
Jameshambleton
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Post by Jameshambleton on Sat 23 Mar 2019, 10:28 am

Just swap a shim over from another valve, then check the difference.
So say you've got a 195 shim in place, swap it with a 197 persay, then recheck the clearance.
so say the clearance is now X. Then do X take away the difference between the shim numbers and the result is the shim you need.

Also I'd always put the shims into the loosest (highest clearance value) as then they'll stay in spec for much longer as the clearance only ever will tighten not loosen. This is the opposite to tappets which loosen.
Beresford
Beresford
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Post by Beresford on Sat 23 Mar 2019, 11:38 pm

@Jameshambleton wrote:Also I'd always put the shims into the loosest (highest clearance value) as then they'll stay in spec for much longer as the clearance only ever will tighten not loosen. This is the opposite to tappets which loosen.  


You're a fountain of good advice James

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