Petrol valve?

[Harri]

Looking at the petrol valve positions, On = on. obviously. Res = reserve. Pri - ?

Barcud

[Tango]

Prime.......opens the fuel flow without the engine running to prime the fuel line and carbs....

[Harri]

Right, so -Prime - before you start the engine. Then - on - when the engine is running?

Would it make a noticeable difference if you kept it on prime when you were riding the bike?

And so, no 'off' position?

Barcud

[Mr Fro]

Can't say I ever needed to use the prime position in normal operation - only if I'd left the bike for a couple of weeks outside in the summer and the fuel had evaporated.

[Tango]

Yeah.....as Mr Fro says, Prime is only used if there's no fuel in the lines or carbs (if you run out, for instance). Normally in the On position the fuel flow is controlled by a vacuum pipe from one of the inlet stubs......so the fuel only flows when this vacuum is present........but, if you run out, it could take a fair bit of cranking on the starter to prime the system up, so that's when you'd use the prime position.....

[Harri]

Thanks guys.

The last run out I had all seemed fine with the idle at junctions. This time out the idle ran too low and the engine cut! I thought maybe I had the prime position on the petrol and the mix was rich? If not I'll have to adjust the idle tomorrow. 2 carbs, could be interesting

Barcud

[eastanglianbiker]

if you had the fuel tap in the prime position then you would of flooded the engine while at the lights causing it to cut out

[Mr Fro]

if you had the fuel tap in the prime position then you would of flooded the engine while at the lights causing it to cut out

Erm... No. The fuel would still have to navigate it's way round the float valve.

Prime position just bypasses the vacuum operated part of the fuel tap.

[Tankbag]

I thought it was for ' Optimus Prime ' mode