Only runs with choke on

[Rob861]

Since last post I have fitted a fast flow fuel tap stripped carburettor cleaned the jets changed the fuel and still doesn’t run without choke any help would be very much appreciated

[missing lynx]

Did you thoroughly clean the carb as well as the jets?

[Rob861]

Yes completely took apart cleaned checked slide unfortunately it’s a jetex carburettor never had any dealings with them

[missing lynx]

Right so has it ever run properly? If not it could be one of the many duff jetex carbs if it was running ok then I would try it without the filter see how that afects it. Whats the air screw set at?

[Rob861]

It was completely rebuilt ran it without any problem for 50 miles then started it one day and it wouldn’t run without the choke. The air screw is about 3/4 of a turn

[missing lynx]

Air screw on jetex carbs is usually somewhere between 1-2 turns out was the engine nice and warm when you set the air screw. But from what you say I would still suspect a blockage in the tickover circuit

[Fast n Furious]

Sounds like the pilot jet is blocked.
Hold the jet up to the light and check the hole is clear.

[CHRIS in MARGATE]

And then it might be an air leak.

[bsso78]

The pilot jet is blocked an air leak would cause it run lean and rev high, putting the choke on would richen it and lower the tickover. Pilot jets on standard carbs can be a pain to clean out but have another go at it, you’ll get there.

[Rob861]

It’s totally clean can clearly see through all the holes

[MickYork]

Try the next size pilot jet (bigger).

[CHRIS in MARGATE]

Your original post states that "after running for 50 miles, it now won't tick over without choke on".
When you say "now", are you implying that it did originally run fine? If so that is not too small a pilot jet but rather an obstructed pilot or it is an air leak causing a weak mixture. If it has always done this,then it is likely that you do need to increase pilot jet size.

If it is an air leak this often manifests itself in the form of hot running that has a smell about it and a reluctance to return to normal tickover when the throttle is blipped.
All tests should be done when engine is warm.

For potential air leaks, check cylinder head nuts after rebuild or exhaust manifold nuts.

[Hat]

Alternatively, could the timing have slipped?

[Rob861]

It ran perfectly fine for 50 miles and yes it does have a hot smell about it

[CHRIS in MARGATE]

Ok It's not the timing. For that to have slipped would mean all 3 stator bolts coming loose or the pickup having become dislodged.

If it smells hot that is because it is running weak.

It suddenly started so check manifold studs and head bolts.

[sunrisemac]

Ok It's not the timing. For that to have slipped would mean all 3 stator bolts coming loose or the pickup having become dislodged.

If it smells hot that is because it is running weak.

It suddenly started so check manifold studs and head bolts.

Might also be worth checking float needle is not sticking and float level is high enough

[CHRIS in MARGATE]

Yes good call.

[coaster]

Ok It's not the timing. For that to have slipped would mean all 3 stator bolts coming loose or the pickup having become dislodged.

If it smells hot that is because it is running weak.

It suddenly started so check manifold studs and head bolts.

Might also be worth checking float needle is not sticking and float level is high enough

If it was the float then I would expect problems when riding rather than tickover but still worth a check though

[Rob861]

I have given up it’s booked in the scooter centre will post the outcome

[Rob861]

Thanks for all the help it was dodgy jets in the jetex carburettor all changed running fine