Was he reaming the guides? How do you get up from a low 4 thou, up to a 8thou clearance with a reamer ??..unless it piles up with chips..
He claimed that on the first 4 guides he ruined (bronzes one from CycleX I brought him) that he overdid the chip load, ended up at .010". Wouldn't you think you'd notice chunks that size coming from the reamer!?
Then he replaced those 4 (using my 4 spare ones from the set of 8 I had) and did it again, coming up with the numbers I showed above, a week later. At that same time, he misread one of the exhaust valve stems with his mic (so he said) and still somehow bored another .002" over THAT figure (+.002 nominal), making it at least .262" for a .258" stem.
On top of that, I discovered the guides are tapered a LOT, wider at the head end, which indicates old, dull reamers, and too much pressure being applied: this makes them tighter through the head itself and looser toward the chamber where the reamer enters.
Normal practice on these guides (in my experience) in a Honda shop was to ream in .001" steps to the target. Sometimes this meant 4 or 5 trips through a guide, but that is the process. Today we have excellent tiny hones so we can ream to the stem size, then hone to the final: he doesn't seem to have this equipment (why? I do...) in his machine shop.
the strange part of all this: he's been doing heads for me for almost 5 years now. I check every one (my OCD is showing?) and when I got 2 heads in May that suddenly went well over .004", we discovered that some of the cast iron valve guides will fracture if you install the bronze liners in them, during the broaching pass. Well, OK, I can live with that: I just had new guides installed to those 2 heads instead and chalked the loss up to schooling. (Turns out, non-Stellite guides are the culprit, here, so post-1972 heads don't qualify). What I discovered in all of this: they don't even check it, now. They say they are "too busy". WHAT!? Too busy for what? To check that you didn't do it right? That's what really got to me.
These bikes run best with tight guides, and lose power quickly with loose ones. The intakes are spec'd at .0005" to .0012" clearance nominal, the exhausts at .0016"-.0024". I've had him building them at .0010" intakes and .0020" exhaust and he's held to it, until now.
So, I'm shopping around for a reamer motor and hone chuck. I just can't accept this, not in my engine, nor anyone else's that I rebuild.
