Timing mark placement

[Chuey]

Now that I've torqued down the flywheel bolts on the engine (1983 R100) I'm tidying up to put into a bike, I realized that I'd not paid attention to where the timing mark was when I took it off. How do I determine where it should be? I think odds are 5 to 1 that I got it wrong.

Chuey

[Major Softie]

Well, you should be able to spot TDC, or close. Obviously the timing marks need to appear in the window very near TDC, with the "S mark" coming the appropriate number of degrees beforehand. You ought to be able to figure it out from that.

[gspd]

Turn the crank so the pistons are at the top of their stroke.
Put the flywheel on so OT is in the window

BTW - the odds are 4 to 1

[Max Headroom]

I've found the odds to work a little different - if there's a 50/50 chance of success, I'll pick the wrong option 9 times out of 10 . . .

[Chuey]

Thanks for the help. As soon as I realized I had ignored the timing marks I just got kind of dumbfounded by that. That's what prompted me to ask that question. As Gretchen and I sat down to watch a movie, the obvious answer appeared in the timing window of my mind. Duh.

Chuey...........I'll let you know if it just happened to land in the right spot. I'll fix it in the morning.

[Major Softie]

Chuey...........I'll let you know if it just happened to land in the right spot. I'll fix it in the morning.

If it did, it's in spite of all of Max's experience with such possibilities.

and mine.


Of course, if you've done no other work, your 1 chance in 5 is not much worse than that. The odds against you having chosen the correct position begin to climb exponentially in direct proportion to the amount of work you have done afterward which would have to be undone and redone in order to reposition the wheel. If you had completely assembled the entire motorcycle, I believe the odds rise to . . . wait, let me check my calculator . . . yes, exactly 1 chance in 14,326,852.