Forum

[Durham Tim]

350 Bullet with Amal Mk1 Concentric carb.
I'm trying to replace the throttle cable on the above, but I just can't seem to get the adjustment right.

On tick-over it sounds as though it's almost running with an open throttle. I am sure there should be a bit of free-play on the twist-grip, but there doesn't seem to be any. So far, I've checked all the following:

1 - Correct cable was ordered from our hosts. Part no 49576B.
2 - The adjustment on the cable between the nacelle and the twist grip is adjusted to it's full extent, it the cable is as long as adjustment will allow.
3 - The cable nipple is seated ok in the twist grip.
4 - The nipple is seated in the top of the carb ok.
5 - There doesn't seem to be any sign of the cable being snagged anywhere between tank and frame etc.
5 - Needle on carb is ok. Set at leanest notch.
6 - Carb idle and tick over balance seem fine, as the bike ticks over ok, when the cable is removed from the twist grip, and pulled manually.

It's almost as if the cable is too short??

Any ideas please??

[Exile]

Try comparing the length of the old (inner) cable with the new.. That might tell you if your cable is too short..

[John L]

Tim - "2 - The adjustment on the cable between the nacelle and the twist grip is adjusted to it's full extent, it the cable is as long as adjustment will allow." Lengthening the outer has the same effect as shortening the inner. If you mean that the midway adjuster is fully wound out, you need to wind the adjustment in to create some free play on the outer. Or have I misinterpreted your posting ? "5 - Needle on carb is ok. Set at leanest notch." Jet needle position has no bearing on tickover function - this is controlled by the carb's idle circuit. HTH.

[Chris Tindal]

As John L says, 'full extent' means long outer and short inner hence tight inner and high tick over. If we have read your post right, you've set it for an old stretched cable, a brand new one should have the adjuster turned a fair way in.

[Alan R]

Hi guys----------Hello Tim}-- EXILE's suggestion is your best starting point ( It's a good tip for any item being changed.)..First question}--Was the cable you removed the proper one anyway??( ie Has anything been modified by you or a PO in the past? )........ as JOHN L pointed out the needle has no effect on idling as this is an entirely separate circuit.....( I'm guessing from that needle position that you have an "open" type silencer ? as No.5 is the richest position ie}-- it's at the bottom of the 5 grooves thus RAISING the needle and allowing more fuel to flow through).. Second question}---On the new cable have you screwed all the adjusters INWARDS ( including the one on top of the carb ?? )..This will SHORTEN the outer cable length...... That last sentence of yours is the real clue where the engine runs normal with the new cable disconnected.....Have you lubricated the new cable ??

[John L]

Alan R - I think Tim's "5" in reference to jet needle is ITEM #5, not clip position.......leanest setting would be the top groove, of course.

[Alan R]

-------oh yes, I see what you mean now ( have been to sleep since posting that last one !!)----

[Durham Tim]

Dear All,

Thanks for your replies. Regarding the length of the old cable, I think Exiles suggestion to compare the old with the new, is a good starting point. Regards,
Tim

[1950s Bulleteer]

Hi Tim. Just a thought, Have you got the throttle and choke cables confused? I suggest this because I had very similar problems a few years back when I fitted a new Concentric, the two cables look so similar that it is easy to use the wrong one. It took ages to find the problem after trying just about everything else.

[Ashu]

Dear All,
I think i have also got a similar issue.
The bike is Electra 350cc CI 5 speed.
Just got the block, piston and AMAL MK1 carb from Hitchcocks.

Trying to fix the Amal Carb with the stock throttle cable
The stock throttle cable has got a nacelle and bend curve at the end. The Part number is #145713/B.
the midway adjuster is fully wound in.

The bike doesn't start. The throttle is really tight.
Opened the air valve a bit and pressed the tickler, but the carb got flooded with petrol.


So kindly confirm is the stock cable short which is resulting the float to slide up and hence the excess fuel flow or should I replace the throttle cable part number 49576B to the one which was supplied along with the carb.