Hi all,
Thought I'd possibly return a few favors and post a solution that worked for me...as opposed to asking yet another question. Thanks to posts by Rod Boardman, Jan Andersson, and others.
Bug: 75 SB, converted to carb, 34PICT/3.
Problem: Would start up fine in cold weather (36-50 degrees F), but would stall after auto choke disengaged. Located in Ottawa, Canada.
After reading a bunch of old RAMVA posts (clicked Search), the following worked for me:
- With engine cold, adjust valves (mine already were)
- Check points are at a 0.016" gap (mine already were)
- Adjust timing to 5 degrees ATDC (mine already was)
- Take air breather off and inspect carb., particularly the choke 'flap'. (with Muir book so I could figure out which component was which)
- Start bug and watch choke flap close/open and the time it starts to stall. Play with choke flap to see what it takes to prevent stall. (see how much play I'm dealing with)
- Put palm over top of carb when running. Attempt to create vacuum and suck dirt out of fuel and air channels. Also check for air leaks (stalled immediately so no air leaks assumed).
- Re-adjust auto-choke on right-side of carb. Loosen 3 small screws. Rotate the inner choke cylinder counter-clockwise, so that the part of it facing you moves down. This causes the choke to be stronger and stay on longer. Fasten screws. (come spring/summer, readjust auto-choke back).
- Start engine and test. Put air breather back on.
- Make sure idle cut-off valve is working...(did not have to do this step so I'll skip the steps--search for this topic if it relates to you).
- Set carb by first warming up engine so that choke is fully open. Turn engine off.
- Unscrew Fast Idle Adjustment Screw until it clear of the stepped cam. Screw it in so it JUST touches the bottom step of the cam. Screw in another 1/4 turn (this sets the throttle butterfly to the required .004 inch).
- Turn the Volume Control Screw (smaller screw on the left side of carb) until it bottoms. GENTLY. Unscrew it 2.5 turns.
- Attach dwell-tachometer (or use your ears and listen).
- Start engine and use the Bypass Screw (larger screw) to set idle speed to 850rpm (before this step I had to bottom out Bypass Screw and unscrew 3 turns as a starting point since I frigged around with it too much before).
- Turn the Volume Control Screw (smaller, lower screw) in or out slowly to give the highest idle speed. Turn it in SLOWLY in to drop the idle speed by about 30rpm. (This sets the mixture a fraction rich like it's supposed to be--screwing it in means less air-richer mix).
- Use the Bypass Screw (larger, higher screw) to reset the idle to
850rpm.Done. I did it!
Tom