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[Daiwiskers]

When it was fitted to asbo30 I just ran the screw fully home now I have a bakelite(spelling) spacer
All it's for is high altitude

[stinkwheel]

But Paul has a 2007 UK model 350 bullet, not an Indian home market electra.

These came fitted with a PAV and points ignition. The PAV is why there is an enormous stack of spacers, one of which is drilled for a PAV take-off pipe which has presumably been blanked off. Although I have seen at least one where they just crimped the end of the pipe over with a pair of pliers.

[Daiwiskers]

Ah that's the thing that causes those back fires on the overrun

Let's think PAV
Pointless air valve
Problematic air valve

Just a thought you could blank it at the manifold connect a syringe full of brake fluid to the open end, then every time you see a electric or hybrid vehicle, or even a green sticker you could smoke them out.
Presuming you don't have a cat in the exhaust of course

[Wheaters]

SW, Yes. I know this discussion has arisen before and I've been told that I was wrong; I think due to another poster misunderstanding what was actually fitted to my own bike.

Hopefully we have established that not all later bikes had the PAV system, even though they DID have the ally adapter/ spacer between the carb and the head.

Maybe someone can clarify - it appears to me from what's been posted here that bikes with the PAV system had only an open stub connector on the ally adapter which obviously does need to be sealed if the troublesome PAV is removed.

Others, like mine, had a similar stub but it was fitted for a different reason. The inlet pipe connection could be closed off by the auxiliary air "Needle" valve, which the PAV bikes don't appear to have.

Is this correct?

Afterthought: Maybe the designer/s of the time who were involved in this was/were also driven to do the strange and probably unnecessary things to the breather systems on these bikes which we often discuss here and elewhere. Which is my task of the day - I've finally got around to removing the troublesome catch can and I've fitted a one -way valve to the breather on top of the oil reservoir, the pipe now goes to the lower chain run. The primary chain breather goes to a sintered brass filter situated under the tank.

[stinkwheel]

Maybe someone can clarify - it appears to me from what's been posted here that bikes with the PAV system had only an open stub connector on the ally adapter which obviously does need to be sealed if the troublesome PAV is removed.

They had a short length of microbore steel pipe (about 4mm OD) pushed into a hole drilled into the plate. I ran an M4 tap down mine and screwed a machine screw in with blue loctite.

I don't know that the PAVs were all that problematic. Just untidy-looking and an unecessary complication.

[stinkwheel]

For what it's worth, here's how I have mine attached currently. The brown thing is a tunfol spacer. I have permabond A135 on the flanges to ensure a good seal.

[Wheaters]

They had a short length of microbore steel pipe (about 4mm OD) pushed into a hole drilled into the plate. I ran an M4 tap down mine and screwed a machine screw in with blue loctite.
I don't know that the PAVs were all that problematic. Just untidy-looking and an unecessary complication.

So this was just another name for what most manufacturers would call an exhaust gas recirculation circuit. As I thought, it appears that the ally adapter on PAV bikes was basically the same device, but as it didn't have a needle valve screw, it served a totally different purpose.

I no longer have the airbox on the bike so I discarded the plastic pipe and just keep the needle valve screwed right in. A longer inlet tract is supposed to provide better torque at low rpm, which is what I prefer on what is a low revving engine anyway.

[stinkwheel]

I think someone smarter than me worked out the carb would need to be somewhere in the vicinity of the rear hub in order to make much of a difference to the performance characteristics.

[Wheaters]

Right - I'm gonna need three feet of fuel tubing and a much longer throttle cable for that.