SOHC.co.uk Forums > CB750

CB750 K1 Valve Timing Question

<< < (4/10) > >>

Oddjob:
Could you not try another cam to see if the results change?

cbxman:
Hello Nigel,

Just had the motor out and the cam cover off.   I was expecting a horror show, but I was pleasantly surprised that it looked OK in there.

There is some slight scuffing on one journal and small bit on one of the caps.  A little bit of chipping on one cam lobe, but not number 4.

I measured the cam lobes.  According to the book, they are all undersized a bit, but actually all very similar.  Your point about re-facing the cams may be true.  They look very serviceable.  However, this does not explain the timing issue. If it was reground, then number four may have been ground off alignment.

I'm not sure where to go next....

Lobo,

Thanks for the idea.  It seems that 750 cams are in short supply, so unless someone has one to lend me, then I would be forced to buy one from eBay....

What I might do is re-assemble. it all and check the timing again with cam cover off.  It should be easier...

Here are some photos

cbxman:
Ho Hum.  It says five photos per post....only one seems to attach.  Last one too.

Ah...

Need to select "more attachments"

K2-K6:
I like your engine lift method Jerry.

Slightly puzzling, and doesn't look bad at all in there. The scuffing is very minor and something that is not unusual as the valve springs push the cam down, along with the cam chain running in tension that way too. Ultimately looks like oil film performance compromise at some point.

Any pictures of the rocker cam follower pads ? A change there in radius can cause a timing shift too as it picks up the lobe earlier or later.

Nigel.

cbxman:
Nigel,

The rocker cam faces look ok.. I'll post some pictures shortly.

Navigation

[0] Message Index

[#] Next page

[*] Previous page