Poor running and throttle cable query A10 SR

[MickFarmer64]

Hi all,

I've recently purchased a 1959 A10 SR. As she'd been off the road for around a year, I've gone over the normal things. New oils, oil tank flushed and cleaned before taking her for a run It's always started relatively easily but had always appeared to be running very rich (Black smoke from exhaust/sooty plugs) I'd always thought she may just need a good run. Anyway, yesterday I took her out for the first time. All appeared to be fine for the first 1/2 mile then it just bogged down if using more than 1/4 throttle. It's now a little harder to start and wont tick over as well has it had been doing.

I'm thinking the most likely fault is with the carb?

I think it's a Amal 376 carb (I've attached a picture hopefully that'll aid identification) are there any basic settings I could look at i.e I think the pilot should be set at 1 1/2 turns out?

Whilst looking at the carb, it appears that it would probably benefit from new throttle and choke cables. Looking online they all seem to shown a 59 SR having a throttle cable with a mid adjuster. Looking at mine there is no adjuster. Is this correct or could it be fitted with an incorrect cable. The other thing relating to the cable is they all mention having a 366 type throttle. I think mine's got the original twist grip so I'm assuming its correct? if anyone could confirm its a type 366 that would be great.

Apologies if these are dim questions - I'm just trying to get my head around things.

[chaterlea25]

Hi Mick,
Do you have the choke in the "off" position?  the cable must be pulled tight for the choke to be in the of position
Apologies if this is too basic a question

John

[MickFarmer64]

Hi Mick,
Do you have the choke in the "off" position?  the cable must be pulled tight for the choke to be in the of position
Apologies if this is too basic a question

John

Hi John, no too basic a question at all. I've been pulling the cable towards me so assuming that's choke on and pushing away choke off? What you're saying sounds like I've been running with the choke on?

[Triton Thrasher]

Hi John, no too basic a question at all. I've been pulling the cable towards me so assuming that's choke on and pushing away choke off? What you're saying sounds like I've been running with the choke on?

Towards you or away doesn’t mean anything. The lever on the handlebar can be either way round.

It pulls the cable to pull the air slide up out of the way of the air.

[MickFarmer64]

Hi John, no too basic a question at all. I've been pulling the cable towards me so assuming that's choke on and pushing away choke off? What you're saying sounds like I've been running with the choke on?

Towards you or away doesn’t mean anything. The lever on the handlebar can be either way round.

It pulls the cable to pull the air slide up out of the way of the air.

Pulling on the lever definitely feels like its pulling something, you can feel a little resistance like its pulling the slide up. Given this I'm assuming with what you're saying sounds like I'm pulling the choke on by pulling towards me? 

[Triton Thrasher]

Look at the cable going into the handlebar lever. Is the cable being pulled, when you move the lever in one direction?

Is the cable being allowed to go slack when you move the lever the other way?

I really shouldn’t say anything else.

[berger]

put your finger in the hole and play with the dingaling lever you will find the choke slide goes uppy or downey . I took my slide out of the brand new amal IT gets in the way, IT  being something else to think about

[muskrat]

G'day Fellas.
Confusion reigns supreme.
Loose cable = choke on, cable tight = choke off.
Cheers

[mikeb]

Mick - the first time i rode my a10 i was very confused. when it warmed up and i went to set the choke 'off' it ran impossibly rich. how could that be? because of what musky says above - the opposite of what i assumed was normal. its worth doing berger's 'digital examination' just the get your head around this. somehow it makes sense. tho there's not much use for a choke on most of these anyway.

[MickFarmer64]

Look at the cable going into the handlebar lever. Is the cable being pulled, when you move the lever in one direction?

Is the cable being allowed to go slack when you move the lever the other way?

I really shouldn’t say anything else.

Yes it’s doing exactly that. I’m sure it’s not running with the choke on.

To my original query are there any other basic settings on the carb I can check. Is the carb an Amal 376 & the twist grip a 366 type & should the throttle cable have a mid adjuster as mine doesn’t? .

Any other suggestions of things to check for the rough rich running?

Cheers fellas

[JulianS]

If not a choke problem then another possible cause, if fitted with original monobloc with thick section O ring, is if the float needle seat has been incorrectly fitted with a fibre washer between it and the carb body, which raises fuel level. Only the "new" monoblocs have a fibre washer in that position. The body of the "new" has a recess machined for the washer, the original does not and the joint is metal to metal.

To be absolutely certain about the choke position the first photo is choke on for cold starting and the second photo is choke off for normal riding.

Make sure the choke cable is adjusted so that it fully lifts the choke slide when off.

[RDfella]

Surely adding a needle washer would lower fuel level, or has this heat affected my brain?

[JulianS]

The washer goes between the float needle seat and carb body so raises the level, the float goes up higher in the float chamber.

[Swarfcut]

   Try  removing the big nut under the main jet to check for muck carried over and blocking fuel flow as you draw more fuel. The main jet can be unscrewed for inspection.

 For now it does not matter whether you have the "correct " cables or twistgrip. As long as the throttle slide can close fully without sticking, and the twistgrip can open the slide fully to reveal just the needle, then you can start the basic tuning procedure. Service sheet 708 gives an overview and specific fault finding information.

 If you are sure it is too rich, lowering the needle in the slide will weaken the mixture, as will screwing out the pilot air screw. Smaller main jet and a  throttle valve with a larger cutaway come next, so worth checking your carb set up against published data as a first step.

 Swarfy.

[MickFarmer64]

If not a choke problem then another possible cause, if fitted with original monobloc with thick section O ring, is if the float needle seat has been incorrectly fitted with a fibre washer between it and the carb body, which raises fuel level. Only the "new" monoblocs have a fibre washer in that position. The body of the "new" has a recess machined for the washer, the original does not and the joint is metal to metal.

To be absolutely certain about the choke position the first photo is choke on for cold starting and the second photo is choke off for normal riding.

Make sure the choke cable is adjusted so that it fully lifts the choke slide when off.

Thank you Julian