Hello all, first time around re-fitting a cam chain (I needed to re-shim the valves). The bike is a CBR600 F3.

I've got the service manual and I've read a few guides, but given the potential for disaster I was hoping some kind souls might clarify a few queries please?

First up, the manual states: Make sure that the T mark (notch mark) aligns with the index mark. But the arrow on the diagram appears to point to the I not the T.



Questions:

(1) Should I be aligning the blue line (I) or the magenta line (T) with the yellow line (index mark)?

(2) With the cam shafts removed, is it OK to turn the crankshaft to line it up? If I understand correctly, the valves should all be closed and out the way with the cams out

The second thing is regarding lining up the cam sprockets. The service manual has them removed then refits them, but the videos I've seen do it with them still on.
The manual gives a vague picture which is going to get you into the ballpark before tightening down the camshaft holders:



There is going to need to be some fine tuning at this stage to get the IN and EX timing marks lined up with the cylinder head upper surface.

Questions:

(3) Is it OK to turn the camshaft a little bit (like 5-10°) to line things up? I appreciate I don't want to be making big movements of the camshaft in this position.

(4) If so, is there a good way to rotate the camshafts?

Apologies for all the questions, but thanks in advance for anyone willing to give me a few pointers!

 

This is the position your TDC and Camshafts should be in for Timing, remember 2 turns of the Crankshaft to get back to TDC, and only turn clockwise so you don't trap the timing chain, sometimes its easier to take off the camshaft sprockets if your struggling, but the "IN" and "EX" have to be at this position for TDC.The Notch Mark is on the timing cover for the"T" to line up to

 

Many thanks for the prompt reply, and for clarifying it is the "I" of the TI rather than the "T".

I found it a little ambiguous because in the section of the service manual explaining valve clearances it is using the "T":



Again, thanks! I knew to only turn it clockwise but I didn't know the reason why

 

It can get wrapped round the timing chain sprocket, in an anticlockwise direction

 

TBH I found it very difficult to time it when I did my valve clearances last year. The marks are on the sprocket but the notch is on the cover which given our 3D vision makes it difficult to gauge proper alignment. Looks different from different angles, somewhat easier doing with one eye close

 

That is called parallax error. I learned that back forever ago when learning to use the most awesome multimeter ever made, the Simpson 260. You have to look at it 100% straight on.

 

Very true, I deal with parallax regularly at work with a badly-designed but very important gauge! So I was very careful with lining this up carefully.

I do have a final question on this particular saga.
I've had the cams out and back in twice now (mixing'n'matching the existing valve shims).
On both occasions, as I turn the crank the chain slack alternates between taunt and loose between the cam sprockets. When it is loose, it looks like it is going to jump a tooth but never actually does.
This is without the cover on and with the CCT retracted.
Is this just the valves pushing the cam at certain points around the cycle, or did I mess something up?
Annoyingly, I didn't turn the crank with the cover off before I started so I don't have any frame of reference to compare it with.
​​​​​​​Thanks!

 

Once you have the camshafts in and camshafts in the correct position, and Marks at TDC and once the cam chain cover is on and CCT engaged, rotate the crankshaft with a socket 2 full turns and check the marks again if they are not exact you could be a link out on the chain, with the right placement it should be good first time, remember 2 FULL TURNS

 

Don't worry about this. This is normal. I noticed this as well. The chain bulges at certain points over the crank rotation, but that's ok.

 

Always line up TDC marks the best you can. Before removal, make a set of marks of your own so you know exactly where it was, as the factory marks never seem to line up perfectly. A little dot of nail polish works well. Then work off your marks....

Just a tip.