Popping in silencer

[RoyC]

Started my bike up for the first time in two months, went second kick.
I have a popping sound in the left silencer, had it for quite a while.
Could this be due to tight rocker clearances ?

New carb and plugs, none resistor type leads.

[morris]

Exhaust popping or banging usually caused by unburned fuel detonating in the exhaust. Maybe your left pot runs a bit richer?
Does it pop when opening or closing the throttle?

[RoyC]

Does it pop when opening or closing the throttle?

No, most noticeable on fast tick over,

[morris]

Leaking exhaust valve?

[Triton Thrasher]

Can be weak mixture.  Maladjusted pilot screw, blocked pilot jet or slide wear.

Air leaks into the exhaust pipe, at the cylinder head, usually cause banging on the over-run.

All this assumes that your engine gets serviced according to the schedule.  I don’t have much sympathy for people who ride around until the valve and points gaps close up and then moan on the Internet.

[RoyC]

Leaking exhaust valve?

This could be too tight a setting on exhaust valve. I will have to look at it.
I don't ride the bike, just start it up occasionally.
Brand new carb, so no wear on slide. All set up for me as per BSA factory specs. 

  https://surreycycles.com/carburettors/amal-monobloc-376-389/

[Triton Thrasher]

If the problem arose after fitting a new carburettor, suspect a too-big slide cutaway.

Also check for inlet manifold air leaks by spraying WD40 or something on the carb to manifold joint while the engine is idling.  If rpm changes, there’s a leak.

[RoyC]

If the problem arose after fitting a new carburettor, suspect a too-big slide cutaway.

Also check for inlet manifold air leaks by spraying WD40 or something on the carb to manifold joint while the engine is idling.  If rpm changes, there’s a leak.

It was there before the new carb (one reason that I replaced the carb).
Already checked the for leaks.

I am still going with valve not closing properly.

[chaterlea25]

Hi Roy,

All set up for me as per BSA factory specs.

Those settings were for the fuel available at the time, this is only a very distant relation to the crap sold now 
Any new carb that I have had to look at after being fitted to old bikes has run lean on the factory settings 

Starting up a bike without riding it and getting everything up to working temp's will cause all sorts of issues


John

[Triton Thrasher]

A valve not sealing will show up on a compression test.