Trying to time my 1983 R65LS. Timing marks are different from any reference works I possess. I have a line, then OT (pretty sure that is what it says) then the S, then a line. Is the S directly at the reference mark or the bottom line?
Thanks in advance,
Tim
Sorry you're having issues, Tim.
Put the bike on the center stand in high gear. This will allow you to bump the rear wheel and move the flywheel very slowly. Removing the spark plugs may help some.
"OT" is TDC, and the "S" is the slow speed (idle) timing mark. Those two marks should be very close to each other, maybe within 3/8 inch.
When you find either mark, bump the rear wheel backwards (in reverse direction). About 1 to 1-1/2 inches back on the flywheel you should see another mark, this one marked "F". It could be covered in clutch debris. You may need to use some spray carb cleaner on the flywheel through the sight window. If it's really hard you might want to enhance the mark with silver Sharpie marker, a dot of red fingernail polish, or something similar.
When you time the engine you'll want to run the revs up to a point where the mark next to the "F" is no longer going up and down, but stationary in the timing window, even if the revs increase. That's "full advance" ignition. That will be at road speed RPM, like 3500 and higher.
Hope this helps.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
I understand all that and have cleaned up the marks so they a visible. What I am not sure of is if I want the "S" or the mark under it lined up with the reference line on the engine case at idle.
Thanks
Tim
Sorry, I don't think you do understand. As explained, you want NEITHER the S or the OT mark. You want to time the engine at Full Advance using the F mark.
Let's look at the question in another way and maybe it will become very clear... Why do we even bother with the ignition timing ? We do it 1) to insure the best performance with available fuels, and 2) to prevent engine damage. At what engine speed do those 2 issues come into play ? Both take place at road speeds, aka "high RPM". Therefore, where the engine fires at idle is totally inconsequential. All the benefits that can be gained from ignition timing come at full advance. And so while it's slightly more difficult, that's the engine speed AND the mark you should use.
Significant degradation in US fuels since your bike was manufactured, plus 40 years of mechanical wear inside your engine are the 2 "elephants in the room" that no manual ever talks about. When we factor those into the equation then we fully understand why the original procedure is no longer the best method.
Hope this helps.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Point taken, thanks
Tim
Advertisement
