Sticking choke mechanism

Post by **Dominic** » Fri Mar 10, 2006 5:46 pm

Hi folks

I have noticed that on my "nearly new" carb (standard fitment on 1098cc - I suddenly cannot remember the carb type!) the jet has a tendency not always to to return to the normal running position after using the choke. It has a new jet and needle. The centreing is fine, the piston drops with that satisfying "clunk" , so I don't think the problem is in this area. Has anyone any experience of this problem, or any ideas on how to cure it please?

Post by **minor_hickup** » Fri Mar 10, 2006 6:26 pm

Have you tried putting some slack in the cable? Try disconnecting the choke cable, pulling out the choke by about an 1/8th" and then reconnecting it.

Post by **Dominic** » Fri Mar 10, 2006 6:29 pm

Yes, plenty of slack, the first "notch" on the cable pull merely takes up slack, bringing the fast idle screw into position against the cam, 2nd notch then opens the throttle, and the 3rd notch onwards progressively drops the jet downwards.

Post by **bmcecosse** » Fri Mar 10, 2006 7:36 pm

Well it's either a frayed or rusty cable - or the return spring is not strong enough. Try dosing the cable with thin oil - if you put it on the outer coiled metal it will seep in to the middle, in time! And look closely at the end to see if it has started to fray.

Post by **Dominic** » Fri Mar 10, 2006 7:41 pm

Certainly the cable has seen better days, seems to run freely though. Maybe an investment in a new one will pay off! Probably will over a couple of tanks of petrol if it cures the problem! Cheers bm.

Post by **Cam** » Sat Mar 11, 2006 4:44 pm

Dominic,

Try disconnecting the cable and seeing if it returns then. I have had jets that are SLIGHTLY bent which drag when they slide up and down causing it to 'stick'. If with the cable disconnected it still does it (assuming a good working spring) then it might be the jet. You could try to straighten it but a replacement one is probably best. If it's fine and return back OK with the cable disconnected then it sounds like you might need a new cable.

Post by **Dominic** » Sat Mar 11, 2006 5:34 pm

Hi Cam,
It still sticks intermittently with no cable attached, and without the piston & needle. Nine times out of ten it is fine, but then it sticks for no obviously discernible reason. It is a new jet and needle by the way.
Dom

Post by **Cam** » Sat Mar 11, 2006 5:44 pm

Dom, sounds like it's a sticking jet then. The fact that it's new does not mean that it's always going to be dead straight unfortunately. I don't suppose you have another jet to try? Anyway, from what you say, I'd take it out and examine it carefully by placing a straight edge along side the jet and seeing if it IS bent at all (even slightly will cause dragging).

Post by **Dominic** » Sat Mar 11, 2006 5:51 pm

If it IS just a bent jet, I'll be quite pleased, as the supplier should replace it for me, it being only 6 weeks or so old. I'll have to try and make time tomorrow, in between building a violin and trying to locate a "funny noise" from the (I think) prop shaft area. That is car, not violin

Post by **Cam** » Sat Mar 11, 2006 6:34 pm

Ah right. Glad you cleared that up. It would have to be a hell of a big violin to have a propshaft in it!

Post by **bmcecosse** » Sun Mar 12, 2006 7:23 pm

Maybe the jet just needs centering - follow the haynes instructions - in case you dont have them - just slacken the mounting, move the jet up/down - then tighten the mountings. It may help. So would a stronger spring.

Post by **Dominic** » Sun Mar 12, 2006 10:48 pm

Hi bm, I took plenty of time centreing the jet, so that it would be spot on. Even with the damper, needle etc all out of the carb, and the top removed, it still stuck in the open position at times. Mostly it closes perfectly, just about 10% of the time it doesnt! Stronger spring sounds good, any ideas where they can be obtained?

Post by **bmcecosse** » Mon Mar 13, 2006 8:37 pm

Afraid not - it really should not need a stronger spring - but if all else fails ! Just ask at the local garage - they may have a junk box you can rummage through.