STRANGE POPPING when ENGINE ENGINE IS CUT

[ANLAF]

Fellers,
Everything, as best as I can do, is properly set-up - can chain perfect, gaps to spec (checked and rechecked) the timing (Boyer) is spot on, floats set to 27mm (BS38s), jets 137.5 and 30, screw 2 full turns out, plugs light brown.

When running the engine is purring really well. I am currently on capacitor (waiting for a new battery).

Here's the thing: it is not starting first/second time as it did (even with capacitor) since I overhauled this week, and when I cut the engine, even from idle, it stops then a pop form each cylinder in turn in quick succession.

In my limited knowledge I suspect one (or a combination) of two things:

1. the timing is slightly retarded; or
2. the mixture is a touch lean.

Any ideas, fellers?

ANLAF

 

[TwoManyXS1Bs]

Try this experiment. Instead of turning off the master switch, pull the fuse to the Boyer, see if it still 'pops'...

 

[ANLAF]

TwoMany, will do, and get back to you.

ANLAF

 

[ANLAF]

Twomany, fuse out and yes, engine stops then two pops (one from each cylinder half a second apart).

 

[ANLAF]

TwoMany - solved it.

Friend brought back my strobe light and the timing was retarded. The popping was probably the compressed mixture being vented before the retarded spark got there.

Got the right tool - got the right answer: timing issue not carbs.

ANLAF

 

[TwoManyXS1Bs]

Wierd. Glad you got it sorted...