1991 Yamaha XJ 900f Timing Marks

Hi Guys

I am sure this is correct but just wanted your opinions of the cam timing for my engine. The T mark is lining up with the top pick up coil with the grey and black wires when the holes in the end of the camshafts line up through the cam caps. It is just that according to Haynes there is a different timing set up on some engines. My engine number starts with 58L0. The 31 A on the timing plate made me think it was an earlier engine but the timing marks indicate it is not. Is the 31 A the part number?

 

I am also interested how timing marks should be aligned with holes. Should they be precisely in the middle of hole or is it fine if those both marks are just inside the holes?

 

I doubt the size of the tooth on the cam sprockets would allow the timing marks to be offset just inside the holes. The picture you see above was with a worn cam chain on my engine which is now replaced.

 

Thats what I have thought also because I have pretty similar situation with xj900 that marks are visible through holes but not dead center of holes.

 

Is the plunger on your cam chain adjuster fully extended? If the marks are visible through the holes and the engine is set to TDC position as above in my picture there is no possibility of the pistons and valves coming into contact. Turn the crankshaft over anticlockwise using a 19mm spanner on the flats on the crankshaft timing plate two full revolutions with the spark plugs out so that your camshafts turn one full revolution there will be no valves hitting pistons. What year is your machine?

 

I think maybe, I had a bit odd situation when I assembeld these. Front end chain guide was broken so it did not provided any resistance to chain and tensioner was fully extended, but I replaced front chain guide and I think it also impacted to chain tension a bit, but I did not checked that was chain tensioner still fully extracted after I assembled it again.

 

To me it looked that one tooth change would throw timing away so that both marks would not be visible through holes.

 

Yes that is correct.

 

There is a small pocket at the bottom of the crankcase at the exhaust side. The chain guide must fit into that pocket. Do you have a Haynes manual and did you see that picture for reassembly. I can post a picture of it.

 

I have Haynes manual but I did not saw picture of the bottom end anywhere in that manual. If you can post picture of it, it would be nice. But I believe I have installed it correctly as I was aware of that but just not managed to find any pictures of it.

 

Here it is. Page 2.11