Joined: Aug 2017 Posts: 807 Threads: 71
Reputation:
9
Thank you all for your thoughts but this one is still baffling me. I cleaned the jet in situ with a can of brake cleaner and once again it all seemed ok for a day or so but today required adjusting again. Oddly the required adjustment has been all one way recently - having to increase it every time, so the lever on the carb is getting higher and higher.
Bob, the carb has been off recently and the flange is flat. The carb and exhaust manifold gasket are new so I don't think it is that. It runs well and picks up cleanly from idle.
I might just have to try a different carb but I'm reluctant to remove it too often as I always struggle to get a seal on the banjo. I know one day it is going to strip the thread!
Joined: Aug 2017 Posts: 856 Threads: 16
Reputation:
10
Location: North Yorkshire
I had a problem with the idling speed on the Pytchley, this has an SU carb but the problem could have been with any type of carb.
I set the idling speed in the usual way looking into the engine compartment with the nearside bonnet half open.
Having set it, I then got in the car and took it for a short drive. I found that the engine was idling much too fast.
Got back to my garage, opened the bonnet and it was idling okay.
I realised that when I sat in the car the engine speed was increasing. The carb is perfectly okay.
I adjusted the throttle linkage slightly and the problem was cured.
Joined: Aug 2017 Posts: 807 Threads: 71
Reputation:
9
Thank you Malcolm, I shall check that out. My impression is that the lever on the throttle spindle is snapping down onto the adjustment screw quite happily but it's worth another look.
Joined: May 2018 Posts: 1,909 Threads: 102
Reputation:
20
Location: Llandrindod Wells
Car type: 29 Special, 30 RK, 28 C Cab
Hi Peter
I had a similar problem on the FZ carb on the RK. I found that was down to the adjusting screw closing up in its thread. A lock nut solved the problem.
Cheers
Howard
Joined: Aug 2017 Posts: 772 Threads: 26
Reputation:
8
Location: On a hill in Wiltshire
An extra spring, temporarily fixed between the ball connector on the carb butterfly, and the chassis, might help in being sure the linkage is closing.
I use a 4" stretchy spring, attached at the top by a thin bit of wire, and to the chassis by the traditional offcut from a wire coathanger - which are not so common as they once were.
Joined: Aug 2017 Posts: 807 Threads: 71
Reputation:
9
27-05-2022, 10:40 PM
(This post was last modified: 27-05-2022, 10:41 PM by Peter Naulls.)
I traced the problem to the operating levers themselves. The butterfly spindle is mangled where the levers locate and despite the nut being reasonably tight there was movement between the two of them - it was possible to force the operating lever relative to the spindle on full throttle.
It will need a new spindle but for now I've tightened it as much as I dare. A rebuild job for next winter I think.
