Had a nice video call with the Guru yesterday, and learnt a few more useful things.
Like: when checking the backlash it's best to do this with the timing chest cover fitted and nipped up!
So - I did that, and:
I'd say that's as close to 1 degree as you're going to get!
The backlash between the timing pinion and camshaft is fine! We had a conversation about the various options for the timing pinion - they were made with allowances for the backlash (-6, standard, +6, +12, etc, he's seen a -20!) and mine is a -6. He initially recommended going up to a "standard" if I could find one, but after rechecking (properly!), it's all good, which is a bit of a relief because these things are just not made any more! If I was to find a 2nd hand one, I'd have no idea how worn it might be (which is the same issue with pretty much all the parts for these engines).
I'm also going to make sure that when I'm doing the valve-timing from now on I'm going to have the timing chest cover fitted and nipped up to ensure things don't have too much play: it makes more of a difference than I realised!
Obviously the guru does this so often, he actually has a cut-down cover with the timing pinion exposed so he can adjust it without removing the cover! Very handy, but massively overkill for me, once I've done this and got it as best I can, it won't be getting changed again. The ignition timing on the other hand....
The guru reminded me of something else: the "critical" valve timing to get right is the Inlet Opening position. Get that right and everything else will follow : the cams and cam-shaft and gear are all one solid piece, so if it's right in one place, it can't be "wrong" anywhere else, so I'll work off that principle.
We also discussed the bent push-rods, it's just something that happens - they're tubes, not solid. I need to find some replacements, and we discussed sources.
This is the worst one: Dial at 0
Dial showing the runout:
FYI: that's the crappy dial, I've discovered that the needle is a little loose and will wander over time. ffs. It's ok for one-off measurements though.
The other rod isn't as bad, but best to replace the pair while I'm here:
He told me that apparantly one of the main suppliers tried to sell ally push-rod tubes a while back, which wasn't a good idea as they all bent! The people who'd bought them were (understandably) pretty pissed off and complained bitterly, but he doesn't know if the company still sells them, or what they're made of: I shall investigate!
The current preferred material for race engines, running full power, is chro-moly tubing, but he reckons that I will be fine with regular steel tubing: I need to take the ends off my current rods (the ends are soldered on), and check the wall thickness, then go find some steel tubing of similar (or thicker) wall and see about making some up; well; presuming I can't find some ready made replacements somewhere else.
hey ho... do a job, make a job (as my ex used to say...)
Oh yeah - I also discovered last night that the classic bike track-day that I was sort of attempting to have the bike ready for has been moved to June or July, from May: so that "deadline" is no longer looming as heavily, phew. What with the discovery of the fork and gearbox leaks I was thinking it wasn't going to be ready, now I still have a vague chance if I still want to aim for it.
