Amal MKII 2900 series needle/circlip!

[themoudie]

Out on the Ducati yesterday, when the engine stalled at traffic lights and then refused to start unless choke was applied. Because temperatures were around 23°C, I thought fuel vapourisation might be the problem. But, after 10 minutes, still wouldn't start unless the choke was applied and using the throttle just caused the engine to fluff and die! Called the naughty van company for pick-up.

Whilst waiting for pick-up peered down the inlet and operated the throttle. Lo and behold the slide lifted but the needle remained seated in the main jet!

Slackened off the carb, took the top off and extracted the needle, then took the circlip out of the slide. Tried to put the circlip back on the needle, but the wear on the 3 points of the circlip and deformation of the needle grooves meant that the circlip wouldn't grip the needle.

Tried to apply gentle pressure to the circlip, using a pair of fly tying pliers, borrowed from a fly fisherman on the adjacent River Tay and only succeded in snapping the circlip. Spring steel doesn't like being lateraly squeezed!

Arrived back home and the circlip and needle came out of a spare carb. Off for a canter and the engine didn't miss a beat.

I know that some users of these carbs change the needle/needle jet and circlip annualy, due to high wear rates. This wear only took 2,500 miles of running, so just be aware if you use Amal MKII 2900 series carbs!

Good health, Bill

[Duccout]

Hi Bill, good advice! The Mikuni uses the same type of circlip and I think that the needle or the circuit revolves and gradually wears.


Colin

[LaceyDucati]

Bill

Recovery truck shame! I think you were warned Three years on race bike is less than 2500 miles and they can start to play up then....

On the smoothbore I made a little nylon collar that sat on the top of the needle which helped hold the needle central and more rigid, seemed to help. Maybe a top hat collar held down by the spring may help the needle/clip wear issue on the standard mk2. All said and done I excuse the Amals foibles because they work well performance wise and they are cheap!

I feel your pain

Nigel

[themoudie]

Aye Colin and Nigel,

Thank you for your additional comments.

At £0-69 a pop, plus VAT and P&P I have ordered three of the little clip blighters! Along with a new 2A1 needle.

When reinstalling the needle/circlip, I used the old galvanised steel retaining disc rather than the fibre disc that is currently supplied and will see how this performs. At the same time, I do note the idea of nylon collars or top hats and may go down that route.

Keep wearing them out!

Bill