Setting Timing

[72598]

Can anyone give me the procedure to set/ check the timing on a R69S. (the timing marks on the flywheel are no longer visable, so I need to set motor at proper place so I can remark flywheel) There is a small cutout about a inch long on flywheel, but no actual timing marks like it shows in manual, or like my other Beemers. On snowmobiles you can do this using a degree wheel on the crank>

[20774]

What kind of flywheel could it be then? You say there's a small cutout...I've seen a lightened flywhee, a Bowman I believe, where a good portion of the outer edge of the flywheel is cutout. What's left along the outer edge is enough for a white strip to be secured which has degree markings from just after TDC to 40-ish degrees BTDC.

Sounds like you know about degreeing a flywheel...are you needing to know the various marks and how many degrees they are? TDC should be easy to find by rotating the engine back and forth at the point where the piston is fully extended. Find the point at which it starts back in going both ways, and split the difference.

Duane Ausherman has a /2 manual on-line at:

http://w6rec.com/duane/bmw/2man/index.htm

There's information on when valves open and close...I thought there was info on the firing points but can't find it...maybe it's buried in the text. I believe this is what it should be:

"firing point 9 degrees BTDC (R69S 12 degrees BTDC) with
governor weights in stationary position". This would be "S" mark.
"Maximum advance 39 +/- 2 degrees BTDC (R69S 42 +/- 2 degrees
BTDC)". This would be the "F" mark.

Probably should confirm that.

Also, I have at home some information at home on the diameter of the flywheel and how much a degree is around the circumference. I think it's like 1mm per degree or 2mm per degree...

[20774]

I got someone a while back to measure the diameter of a standard flywheel. It was 8.75 inches which ends up being 222.25mm. Circumference is 698.22mm. Therefore, 1 degree on the edge of the flywheel is 1.94mm.

I made the note of the static and full advance settings as follows (different than what I posted above):

R69S static timing mark @ 9 deg BTDC – 17.46mm or 0.69 inches BTDC
R69S full advance mark @ 39 deg BTDC – 75.66mm or 2.98 inches BTDC

These new degree numbers agree with my /2 owners manual.

[72598]

Thanks that is exactly what I was looking for. It is a stock flywheel but has enough surface rust as to make finding marks impossible. (poor lighting and failing eyesight are factors also)