Cam chain timing

Hi there,
I'm reassembing a 1980 650 Seca & can't get the timing dots to line up - I'm pretty sure if the cam sprocket is rotated another cog it will make things worse. One of the dots is misaligned by 1/8" and the other is just over 1/8" .
The way I see it, there's 3 possibilities:

• The sprocket and cams are not assembled correctly
• The misalignment is within acceptable limits
• The cam chain is stretched and needs to be replaced

Photos attached - any suggestions would be greatly appreciated

 

It looks like one of the two cams is one tooth off..?
How many miles did the girl do?

 

Is your cam chain tensioner near the end of it's travel? Which mark are you using on the crankshaft the T mark or U mark (if it has the same mark as the 900f on the timing rotor. The T mark is top dead centre and the U mark is the advance mark I am sure. Looking at the pictures though it is most likely one tooth out.

 

I don't know as it had a non-standard instrument console when I first got it, but probably not particularly high mileage, it's in fairly good condition.
Tried moving the sprocket but might be doing something wrong as it either makes it worse or the sprocket bolts don't line up.

 

I haven't installed the cam chain tensioner yet, will that make any difference?
Its set on the T mark on the crankshaft

 

T mark is correct. Try installing the tensioner to see what happens to the cam timing mark alignment when your T mark is aligned at the crankshaft. Might still be one tooth out though.

 

I suspect you're right about being one tooth out, but will install the tensioner in the morning - thanks.

 

You can use a spanner on the flats next to the cam timing marks the dot and arrow. If an assistant does this you can line up the cam sprocket easier. If one of the valves is slightly bearing on a shim it can throw off the dot and arrow alignment slightly when the chain is not tensioned.

 

You can also use a clean piece of wood through the tensioner opening to see how pressing on the tensioner guide moves the cam alignment. This saves fitting the tensioner and is a quick method l use to ascertain how it affects timing mark alignment. Say wood approximately 10mm square and 200 mm long.

Chain has to be tight from the crankshaft to the exhaust camshaft and all the slack on the tensioner side.

 

SUCCESS! The cam chain tensioner didn't make any difference so reluctantly came to the conclusion the sprockets need realigning. Your suggestion to use a spanner on the camshaft was a great help, thanks very much