timing a R75/6

[Markst1]

I had my recently purchased 1974 R75/6 begin to stumble and run rough. When I checked the points, they were barely opening. I cleaned up the points with an emory board and regapped them (15/1000in), timed the bike with a static light and it ran great (much improved from before the problem began, especially between 4 and 5.5 kRPM.) The next day I put a strobe light on it and found the timing to be very advanced. I tried to retard the timing, but can't retard it enough to get in spec. The plate is moved to the max retarded position. I can not see the S mark. The F mark is below the hole at idle, at the hole at 2000 RPM and above the hole at 3500.
Any suggestions? Might a new set of points help? Is it bad for the engine to run advanced like this? The engine does seem to feel and sound fine like this.

[James.A]

It is very bad to run your bike with the timing too far advanced. Check out the thread on this forum entitled "Holy Piston". Getting the point gap exactly right is very difficult with the fly weights in the way. Chances are, the working point gap is too wide. I've done this very same thing myself. It is very aggravating, but you must get the timing in the ball park. Keep trying. New points are always a good idea.

[Markst1]

Thanks James,
You were right-on. The point gap was too wide, and thus the points were opening too soon. So the timing was way too advanced and couldn't be adjusted.
It is difficult to adjust the points given their location behind the advance mechanism. I think a saw a useful tool that could be used to gap the points without having the advance in the way ($7.95). Any experience with this?
Anyway, bike runs great now and is in spec.
Thanks again.
Theo Marks

[dlearl476]

I just went through the same thing with my /5 and I'll offer a couple of points. (sorry)

Points are cheap enough to replace, rather than "making do" with an old pair and "wondering".

Checking the dwell angle is infinitely more precise than setting the gap with a feeler gauge. I don't have the spec in front of me, but it should be in your book. (IIRC, 110 degrees which works out to 55 degrees on the "4 cylinder" scale on most instruments) After trying 4 or 5 times with the feeler gauges, I got the angle spot on the second time with a meter.

And lastly, when you replace the points, install new advance return springs. An excellent mechanic I know told me to do this before I did ANYTHING else with the timing. He was right.
There are two types, I believe your /6 might have the heavy duty version already, my /5 didn't so I changed them out.

FWIW, Irv Seaver has all this stuff in stock, if your dealer doesn't.

[James.A]

Mark, I found a link on Duane Ausherman's web page to order a gapping tool with the .016 feeler gauge attached. I ordered 1 for my /5 and 1 for the earlier vintage bikes as well. I can send you his e-mail if you like.