Forum

[dalgrae]

Just a thought I had a new concentric carb supplied some some ago ( not from our hosts) which had the revised fixed idle bush feature but also had an idle jet also fitted,which should have been removed.

Colin

[MichaelV]

Good ideas, there, guys.

I'll check the float level and possibly try a larger needle jet too.

Colin, I did take the float bowl off and check which type of pilot was fitted and there wasn't a two stroke one screwed in but it does have the thread for one.

Thanks all.

Michael.

[MichaelV]

One further thought that I'd appreciate anyone's input on.... I'm going to check the float level first but can't get a definitive answer on where to set it. AMAL themselves say a certain distance down in the bowl whereas our hosts technical section suggest it ought to be "level with and a bit above the float bowl lip, with gasket fitted".

Thoughts, anyone?

If I can't figure out which I suppose I'll end up trying both!

I have ordered an iridium IX plug - should be good for another few mph!!!!

Michael.

[Haggis]

From Amal website technical info.
The correct fuel level for all Mark 1 Concentric carburetters is 0.21" plus or minus 0.040" below the top edge of the float bowl. Thus when the needle valve is being held shut by the tangs of the float, the level of the fuel will be between 0.17" to 0.24" (4.33mm to 6.35mm) from the top of the bowl.
http://amalcarb.co.uk/technical/

[Cranky]

I was going to say float level too low. when you brake the fuel goes to the front of the carb starving out the idle jet. When I say idle jet I mean the jet and not the adjustment screw.

I am not familiar with Amals but if the idle jet is at the back it is low If the idle jet is at the front then its high and flooding the idle jet. However this would not make it start so easily as the OP says it does,

Its all it can be. My VM 32 has a flat plate a round the 'main' jet to help stabilize fuel splosh. The idle jet is up inside and will not suffer the same splosh conditions as the main, but it will flood.

If its a bolt on right to the head fuel splosh or splash can be a problem due to vibration.

[MichaelV]

Haggis - good man. I'll try that setting first, then. Thanks.

Cranky, it bolts to the head with an adaptor so, almost, a direct bolt on. I'm going to check float level, test it and then report back here.

Michael.

[dalgrae]

Hi so please for my benefit and understanding,how please does the float cause this problem,as I cannot understand that when coming to a halt even very gently this causes the engine to stop ,my logic says the float chamber is still full of fuel.

Colin

[MichaelV]

To be completely truthful, Colin, I have no idea but I do know that everything else is set up correctly.

It could be either that the fuel level is too low so when I close the throttle and pull in the clutch there isn't sufficient fuel in the bowl to keep it alive, but by the time I've kicked it up again, the bowl has filled sufficiently to feed the idle circuit again. Or, it could be that the bowl is too full so that when I pull in the clutch it dies because its too rich, fuel sloshes up and throttles it with what's called a rich cut, and then, as everything is set up ok, it kicks straight back to life and idles again.

Like I've said, I have no idea but it is driving me nuts so I'm willing to try anything. I'm clearly no carburation expert so these are just my thoughts not in any way a proven theory.

Michael.

[Nitrowing]

Just as a curveball...

Your clutch isn't dragging?

[MichaelV]

Hi Nitro,

I don't *think* so, but I'll double check.

When I rebuilt it with the 535 big bore kit, I fitted, all from our hosts, PART No. 90010 CLUTCH PAD/ROLLER, INDIAN MADE 4 SPEED & 5 SPEED, a PART No. 90041 CLUTCH SERVICE KIT (IMPROVED) and a PART No. 90221 GEARBOX OUTER COVER STIFFENER ASSEMBLY, 4 SPEED and spent quite a while setting the clutch up, but as I've said I'm after any and all ideas so I will certainly check again.

Thanks mate.