AJS & Matchless Owners Club

Hi All, having trouble with a sticking throttle. I have a '54 18 S fitted with an Amal Concentric Mk 1 carb, which worked perfectly for a couple of years. Earlier this year it started 8 stroking, missing and generally running badly, diagnosed as blocked idle jet. This has been fixed and carb cleaned with carb cleaner, and I am now fitting it back on. I have been running it on its worn original 89N carb. Having fitted the Concentric back on, using the same twistgrip and throttle cable that worked on the Concentric previously and the 89N, the throttle sometimes sticks just open when I twist the throttle and let it go. If I jiggle the cable it shuts completely. I have lubricated the cable thoroughly, the inner slides easily in the outer, the carb slide moves freely in the carb barrel. All is assembled correctly in the carb. Any suggestions? Cheers, Andy

One of the usual causes is overtightening of the nuts holding the carb to the manifold. If you ease the nuts off slightly you may hear the slide drop.
Dave.

Hi

Have you altered the cable run at all / nipped it a bit when re-fitting the tank?

Regards Mick

dave16mct wrote:One of the usual causes is overtightening of the nuts holding the carb to the manifold. If you ease the nuts off slightly you may hear the slide drop.
Dave.

I had exactly this on my twin; slackening off the manifold nuts a bit fixed it. Also check the cable run. Lastly, check that all is well at the throttle end. A friends bike was doing this, and the cable outer was coming out of the throttle and catching on the throttle body if the throttle was closed quickly.

Malc

I had a problem like tis with a Concentric that had done a lot (and I mean a lot) of miles.

I bit the bullet and bought a "correct" Monobloc from the Spares Scheme - what an improvement on all fronts.

Johnny B

When I was eighteen, I upgraded to a AJS 500cc from my 1936 22 250cc. On the way home I blipped the throttle before changing down when approaching some traffic lights - throttle stuck wide open.
Exhaust valve lifters can come in handy sometimes BANG! BANG! BANG!
Never happened since.

Yep and I've fitted a kill button from handlebars to the SR1 magneto.

Unfortunately it doesn't seem to affect the other road users who are irritating me.

Johnny B