Carb Priming

OK, age old question I know, but I can’t find a reasonable answer, and before I spend hours coming up with my own solution I thought I’d ask the great and the good.

My poor old carburated 900 Monster doesn’t get used anywhere near as much as it should for lots of reasons, so sometimes it sits around for 2 or 3 weeks evaporating the fuel out of it’s float bowls.

I keep the battery topped up on an Optimate, have made up myself all new starter and earth cables using properly crimped marine grade tinned 16mm2 cable, and have cleaned and protected all the earth points. It’s also had the Vacuum fuel tap removed by a previous owner in favour of a simple ball type valve.

It now spins up really well on the starter, but still needs to turn over on the starter for quite some time before it fires up. If it’s been used in the last week it fires up instantly.

This is because of course the Vacuum operated fuel pump needs to prime the float bowls before the fuel can be delivered to the cylinders, but the engine needs to be spinning to operate the pump.

The same age Carburated SS I’m building does of course have an electric pump in the tank with a return loop from the system, so leaving the ignition on for a couple of seconds should prime the float bowls.

I was thinking of changing the Monster to an electric pump somehow, I understand an early R1 pump has been used in the past, but I would rather not add complication to the simple Monster system, especially if I ever need to bump start it for some reason.

So I’m wondering if anyone has found a way to prime the carbs manually using the vacuum pump?

I assume a T piece into the hose from the inlet manifold that you could have a removable bung in, would allow you to suck and blow down the pipe, but I’m not sure I want to do that.

Has anyone taken a pump apart and fitted a ‘Tickler’?
Something like a lever sticking out that could operate the pump manually.

Does anyone have an old Knackered pump they’d like to donate to the cause that I can strip down and experiment on?

Any thoughts?

Thanks

Nasher

 

I do tend to keep the tank topped up as much as possible to reduce the condensation build up.

Good idea regarding the outboard priming bulb, I even have several in the garage because I play around a lot with boats and outboards.
They are normally quite slow to reform back into their natural shape and pump quite a large volume of fuel in each cycle, so might not be suitable for the many small variations needed to operate the pump on a 'T' piece, but I suppose a small one might fit between the pump and carbs, and might drag fuel through the pump.

I need to see how a pump works really to know.

Food for thought, thanks.

Nasher

 

Dukedesmo hi.
As mentioned the vacuum fuel tap has been removed from my bike by a previous owner, so isn't a problem in this case.
I've actually tried leaving the simple ball valve turned on to keep the bowls topped up, but had a few drips from the overflows after only a few hours.

I'm sure the pump works off the pulses in the inlet tract moving a diaphragm backwards and forwards to pump the fuel, a constant suction would just move the diaphragm once.

As you say, the std carbs are really high up under the tank, so I'm not sure that the last of the fuel would fill the bowls.

I don't really want to do the electric pump conversion that I know is the answer, as I enjoy the simplicity of the old carb monster so much.

I've had a quick look at the Outboard primer bulbs I have in the garage, and am kicking myself I didn't think of them before.
If a smaller one is available than the ones I have then it might work, but only if the Vacuum pump 'rests' in a position where fuel can be drawn by the internal valves etc.

I need to learn more about the internal workings of the standard pump.

Nasher.

 

Arquebus
The Monster only has the external Vacuum operated pump and filter, no internal one.
Nasher.