cam timing on XS1

[TC2000]

Hi All,
I just bought a XS1 1969.
Checking it all around, I notice the cam is retarded around 10 degrees (theoretical mid point 100 deg. ATDC, but I measure 113 deg. ATDC +/- 4 deg). Then the ignition plate for right cylinder is at the edge of the adjustment range and the advance is still low.

Questions to the gurus:
Is it possible to remove the head cover with the engine still in the frame?
Then is it possible to slide the camshaft bearings out and move the chain one tooth with the engine in the frame?

Or should I go the hard way and remove the engine from the frame first ?

Thanks for your help !

 

[TwoManyXS1Bs]

Welcome to the forum, TC2000.

Your cam chain is stretched and must be replaced.
Engine removal required for this.
Do not try to adjust by repositioning the camchain on the cam sprocket.
A one tooth change will be about 21° change in timing...

 

[TC2000]

Thank you, good advice

the Clymer manual says one tooth is about 10 degrees, but it must be wrong:
the camshaft sprocket has 34 teeth, then 10.6 degrees, but this is at the camshaft. At the crank, it will correspond to twice that value then around 21 degrees.

So like it is the camshaft is retarded about 10 deg, and one tooth change would make it 10deg too advanced, which is worse for the engine.

Do you think the chain replacement is urgent?

have a nice ride,

 

[gggGary]

Can't see the front guide to gauge how worn it is until the engine/head is removed.

 

[TwoManyXS1Bs]

...Do you think the chain replacement is urgent?

No, not yet. But highly advised.
My XS1B's camchain is also stretched about 10°, measured at the crankshaft.
More discussion here:

http://www.xs650.com/forum/showthread.php?p=438061#post438061

Our early cylinders have a bridge in the camchain tunnel, between the cylinders. If the chain becomes too stretched, there's a risk that the camchain will try to 'saw' against that bridge. A sign of this would be camchain 'clatter' sound, with fine aluminum flakes in the oil. Note the camchain scrape marks in this picture:

 

[TC2000]

Thanks a lot.
This is great help

At present, no rattling noise from the chain, I will check debris in oil...