Adjust valve clearance

I do my very best to tell the correct things, but of course I can give you no warranty!

Tools you will need:

Be sure, that engine is cold (35 deg C max)! Heat will affect valve clearance!

Dismount all facings (except front facing), seat and tank. Remove the air dome by detaching the clamps on both carburetors and the air cleaner housing. Loosen the right radiator (3 SW10 screws). Just loosen it, do not remove the tubes.
Now there are two ways to do this job:

  1. remove the complete valve housing cover by loosening the two sw10 screws or
  2. remove the small (aluminium) caps by loosening the two sw8 screws (to reach the inlet valves) and the sw24 screw (for the exhaust valve).
I prefer removing the small caps, even if it's a terrible fumbling job. But the other one is too, respectively.
Remove the 2 aluminium caps on the left engine cover (sw10 and sw6 Allen-head screws (Allen-head is what in German is called "Inbus"). Put the piston of the cylinder you want to check to upper dead center by cranking the engine CCW with a sw17 wrench (hey, ignition off!) and peeping through the upper hole, bringing the marks on the camshaft (FT for the front, RT for the rear cylinder) and on the engine housing to straight line.

Attention, all valves of the inspected cylinder must be moveable!. Otherwise crank the engine CCW for another 360 deg. Now check the valve clearance with a gauge. It's a good idea to bend the blade to an angle of approx. 45 deg. The proper value of the valve clearance is:
construction year '87-'88: 0.1 mm for both inlet and exhaust valves
construction year '89- : 0.15 mm for the inlet valves 0.20 mm for the exhaust valves

If not proper, loosen the sw10 nut, and with a pair of tongs or with a 4mm wrench (if available) adjust the clearance by turning the square nut (CW: less, CCW: more). The clearance is correct, if you can move the gauge "with a light suck" between the valve and the adjust screw. If you're not sure, try the next bigger gauge. If it slips, adjust again. If it doesn't, leave the gap as is. Always remember: If in doubt, rather leave the gap a little too big than a little too small. If it's too small, you risk severe valve damage.
Fasten the sw10 nut and check again. If not proper, do it again. Mount the caps and proceed with the other cylinder. When done, check the idle mixture (coming soon), and carburetor synchronisation. Mount tank, seat and facings, clean your fingers, have a test ride and have fun.
Lucky enough, you must do this job only every 12,000 km!

Pictures scanned from "Reparaturanleitung Honda XL600V" by Bucheli Verlag, Zug/CH

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