AJS & Matchless Owners Club

Does anybody know what the valve to guide clearance should be for new guide and valve ( i/l and exh ) for 650 twin.

I'd say minima of 2 thou in and 3.5/4 thou ex and that a thou more is probably ideal for the throttle-happy. Manuals don't specify as far as I can see, some modern info on t'interweb suggests rather more as an upper limit, but anything less is I think v risky.
I say that having had an ex valve seize on another marque (iron head though) after I'd made a guide that was a fraction tight. It worked fine until I gave the thing some serious beans for half an hour . . . then, calamity! Managed to salvage it and clean it up for a 4/5 thou clearance and all was well.
I've found that significant wear on the inlets = smoke and increased oil consumption on our motors: on one of mine, replacement inlets 'cured' what new rings etc didn't . . . should have gone there first!
Others may have more precise better info . . .

Thanks Bill, as I thought really. I was asking on behalf of somebody else for a second opinion.

Page 12 in the link below gives clearances for a 350 single much in line with Groily's figures. I guess the stem diameters of your 650 are much the same as the for the 350 since after all, a 650 is only two x 325 cc cylinders.

http://archives.jampot.dk/book/Workshop ... ndards.pdf

valve to guide clearance varies on the year , but typically .002 to 0.0025 was the new clearance
Exhaust guides on the upper limit as they run hotter