Twin 'Popping" ?

[racer7]

I have a CB350 twin. It has the standard carbs, but they've been bored out to 31.8mm.
Starts good, revs good. At all throttle openings however, it pops and bangs through the 2 into 1 exhaust. From holding a hand over the bell mouths, I have the idea that it's the right hand side doing it (missing?).
Carbs are clean, diaphragms good.
So could it be ignition (points) lean Pilot.....help please!
It should run Avgas, but I don't have any, so using Caltex PULP 95 Vortex. Just in the driveway
racer7

[Andrew]

Sell it and buy a two stroke.

or you could have leaking inlet manifolds?, how are the valve clearances? Sound like you could have a dead spark plug?

Try changing the plugs to new ones or swaping the plugs side to side, same with the coils if you have two.
Fresh fuel
If its lean on the pilots, turn the choke on does it stop poping? or block half the air intake up.

[racer7]

Thanks for that. I did try blocking the inlets, which is how I concluded it is the right hand side. From the pressure coming back out of the bell mouth, coinciding with the pops and bangs. I hadn't considered an electrical problem (ignition). I have a total loss system with points. But I've had a Boyer Brandsen/ Newtronic Electronic unit sitting in a sealed box for about 5 years!
Since the left hand side is good, I think you've put me on track.
This is a 'P4 CB350' I'm putting together. With lots of help!
Inspired by the Guys at the "Barry Sheene" 2010.
Much appreciated.
racer7

[stanno]

I've had the same problem with a 4 cyl in the past. I found the carby inlet manifolds leaking at the head. I resealed them with a bit of Permatex. They had gone a bit hard over time and I eventually got new ones, but the Permatex worked fine. A good high temp 3 bond is the best sealant for that application I would say, after having used it for a while

[racer7]

Hi Guys
I replaced the carb inlet rubbers, put in some fresh Avgas...sweet as!
Thanks for the heads up
racer7