TOPIC:

Got back to this thing today. Tried to get the valve clearances sorted and the points set up. Got the points done and half of the valves but ran out of time (was on a tight schedule). After putting the cam chain tensioner in I noticed that the intake cam was "jumping" to the left a bit before the #4 intake valve starts to open. About 90° later it jumps back. As far as I am aware the cam is held in place by the left hand cam cap - I'll take that off and check it for damage tomorrow. Any idea what could be causing this and if it's a problem (or will it sort itself out when the engine is up to speed)? Here's a video where you can see the cam shifting:




I also noticed some corrosion on the lobe of the intake cam (just #4, the rest are fine). Is this anything to worry about or should I just check it again at the next oil change?

 

That seems like a lot of "end float" ????

That's what I was thinking. Probably not a good sign that it moves back and forward in the same spot with each rotation (unless I turn the crank really slowly...). I think it might be a good idea to pull the cam and check everything, or at least pull the left cap off and check for damage.

Is the sprocket running true? If not the chain will pull sideways (still seems excessive though)
PS: does it happen on all four cylinders as the inlet cam "loads up" on the valve spring or only one?

I'll check. But I would assume that would just cause the cam to be pulled to one side and stay there, not shift across with each rotation of the sprocket. I did think the chain was maybe catching on the rubber dampers on the sprocket as it seems to shift when the chain leaves one section of damper and hits a part of the sprocket with no dampers. It's hard to check by myself though, so I might need to drag the boy over to the garage tomorrow.

If that cam is moving laterally I would guess the entire camshaft is moving and then moving back.  You might want to check all of the intake cams and both bearing caps to see if there is an obstruction of some sort.

Took the #1 and #3 cam caps off today. The cams have chewed away at the sides increasing the end float. Interestingly the intake cam has stopped sliding across at a certain spot since I took the caps off and put them back on. I also finished adjusting the valve clearance but I don't think that would have made any difference. 
I may have done something a bit stupid: I loosened both the caps on the intake cam to check them but didn't bother taking the chain tensioner out. This basically left the cam chain holding the cam in place. Not ideal but I'm assuming that chain can take a lot more of a beating than that... Still, will try not to be so lazy next time around.

After doing the valve clearances I started on the rear brakes. What a nightmare it is getting the spring on the brake pedal mounted! I gave up with the new spring and put the old one back on. The only way I can see the new spring going on is if the exhaust, the clutch cover and the footrest studs come off. Needless to say, the powdercoating where the spring hooks over is now less than mint - good thing you have to get under the bike to see it.

Will keep going on the brakes and post some pics tomorrow.

Here are the cam caps. Do I need to do anything about them? I know a guy that could probably repair them with laser welding.
Intake:
 

 

Exhaust:
 

 

It does look like the caps weren't located correctly on the cams when they were pulled down, as far as I can see the end float is controlled by this section of the cam (see below) I think that if you clean up the caps so there is a nice "square" recess for the cam to locate in you should be fine
Is there any damage on the cams ?
With the brake spring have you tried bending it and packing it with washers then bend it back the other way and pack the other side ?

 

No visible damage to the cams. IMO the damage is too clean to be from the caps being tightened down when the cam wasn't aligned. Pretty sure that would have made more of a mess and the threads in the head would be toast. It looks more like the groove has been "machined" out by the spinning cams (the cams fit in the groove perfectly when the caps are installed).

The washers might work on the brake spring, but I still think the footrest studs would have to come out.

Maybe some of the guys who are much more intimate with these motors can throw some light on it 

A bad cam chain guide guide/Idler on the intake side can effect a lateral misalignment of the cam chain.

I don't think that's much of a problem. 
Steve