Timing marks

Wed Aug 25, 2004 9:49 am

Last night I adjusted the valve lash on my Cub and I wanted to check to see that I did it correctly. I used the method described here and adjusted 1,2,3 & 5 (if I recall that corectly) at No. 1 TDC and the remainder when No. 4 was TDC.

Here's the part I think I may have screwed up. My manual states that to get TDC, turn the crank until the piston is pushing air against your thumb when sealing the spark plug hole. Then continue to crank until the timing mark on the crankshaft pulley is alined with the pointer. Perhaps I missed it in my reading, but my pulley (1957 standard Cub) has two timing marks (pretty close together). I set the gap using the first mark. Was this correct?

My Cub is smooth running at moderate and high speed, but has an irregular miss (a poping sound) at low idle. It was quite pronounced, but after rebuilding/adjusting the carb and adjusting the valve lash it seems to be considerably better. Is there any other adjustment or cure I should use to eliminate or reduce the problem further?

I would like to thank everyone for all the help they have been. Without your patient advice, my Cub would probably be a pice of garage art (it was a lawn ornament for the PO). So thanks again guys and gals.

Wed Aug 25, 2004 8:35 pm

Slappy,

The first mark you came to was 16 degrees BTDC (before top dead center). You would want to rotate the crank to the second mark which is TDC (top dead center).

Thu Aug 26, 2004 5:34 am

Thanks Donny. Looks like I've got some re-adjusting to do.