LCGB Forums

Setting my carb back up after a rebuild and I can’t get the engine to tickover on the screw alone, I have to adjust the cable to get it ticking over. Any ideas what could be wrong. It’s an avanti tt3 and I’ve done over 4000 miles on it before rebuilding. Done a leak down test so no leaks but I can’t see why the tickover screws doesn’t work.

choke sticking, air filter needs cleaning, muck in jets, timing too retarded, stuck ring, etc, etc.......

Usually after a rebuild you get a slower tickover due to the fact that everything is less worn and the sealing is better. Don't really think anything is wrong, you have merely taken the slack out of the cable.

Rich'

I have had issues with PHBH carbs where the screw-in tick-over adjuster doesn't actually do anything. Either the "point" is too short, or the external spring is too long.

It is not wrong to adjust the cable to get a tick-over. The screw AND the tightened throttle cable are doing exactly the same thing, by lifting the slide to allow more air beneath.

Thanks guys it seems to be a bit different with a different slide. Still a 40 but the screw moves it up a bit more. Choke is fully closed as I set it so full lever movement opens it half way. Carb cleaned and blown out, timing still at 17 btdc and new rings fitted. I’m happier now the screw does a bit so I’ll run it again as usual.

I've had a slide worn away on higher mileage carb, the tickover screw had worn a little groove in the slide making it ineffective.

That's interesting to know you have had problems with the idle screw wearing a grove in the slide, mine is exactly the same. I have done nothing with it using the theory that if it was replaced the same thing would happen.

Actually, I have just replaced the 40 slide with a 45 and upped my pilot and I'm now thinking the 40 was too rich and may have been the reason I was struggling to get a tickover. Who knows with these pesky scooters?!