I've always followed the .10 mm inlet and .20 exhaust for the valve end float. But for better starting I think I could open up the inlet to maybe .15 mm. I noticed right after a valve adjustment it starts better then after a few months without adjustment. (I was in there doing the pushrod seals so I noticed). I think, airheads tend to tighten up through many head cycles.
I had always gone after the carbs for starting issues, but I wonder. Sorry if this might start a religious debate.
thanks!
IMHO, Airhead valves tend to tighten due to valve seat wear. As the valves recede into the valve seat, the valve clearance closes up. This is not shoddy production or poor materials, but rather modern day riders not being able to buy the same fuel these bikes were designed to run on back in the 70's.
Opening from .10 to .15mm Inlet clearance is not going to cause any issues, and if you seem to get better performance from your bike then by all means do it. But I doubt it's a change everyone needs to make. Still it's an interesting point.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
I think it worked! Kept the intake a generous .01 mm and a little less for the .2mm exhaust. Don't think it's a full .05 on the intake (the .02 won't slide in), but nicely open on the intake and it starts up better than ever. I've been the keeper for the past 10 years.
Should say I had Rick Jones freshen up the starter, but nothing crazy. It simply spins as it should.
Thanks for the advice.
I have always adjusted Airhead valves on the loose side. With the current 95 R100RT I go with .006" (.015mm?) on intake, and .010" (.025" on exhaust. Back in the day, with a 79 RT, and later an 82 RT, since the exhausts were prone to early closure (even after upgrade by one of our BMW gurus), I'd set the exhausts at .012" (.03mm?) Still, could not get 3000 miles before they'd all but close up.
That's one thing I am loving about this mono shock Airhead, then FINALLY fixed the exhaust valve closure problem. When checked at 10,000 miles, the exhausts were at .009", and I am thrilled. The 78 R100/7 and 76 R90/6 I had would go 8000-1000 between adjustments, but they'd be all but closed up by then. Yes, I know the factory said to adjust them every 5000, but that's a PITA, at least to me.
Should say I had Rick Jones freshen up the starter, but nothing crazy. It simply spins as it should.
All he did was re-pack the ball bearings (or replace the bearings). We've discussed this situation before in these pages. The OEM grease simply gets super viscous and pasty after 40 years, and the motor simply can't rotate. Same thing happens in your head post bearings and wheel bearings.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
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