Scooterotica

Hey all,

I have a Li150 S3 with a Jetex SH2/22. It's occasionally hard to start, and when I pull the plug it's bone dry. When it occurs, if I bump start, like down a hill, it fires no problem. Once running it's great.

I think I'm encountering the "sticky float needle" problem I've read about on these Jetex carbs, where sometimes the float needle sticks and doesn't allow fuel into the bowl.

Can someone name, or point me to the correct float needle replacement for this issue?

Thanks!

If its the needle you can get a Jetex one from Scooter Restorations, its a red one for unleaded, also check the float itself, the ethanol in the fuel can make it swell and bind on the pin or foul on the float bowl edges

As essexgp said, float needles are available. Not all Viton tipped are red. I bought a couple from Scootopia for VHB's (the same) which are black & they are Viton.

Bump starting will 'unstick' the float/float needle enabling starting, so you have kind of proved your theory. Same as once running, the vibration will stop the sticking too.

They all do it at some time or other,what you need to do is remove the float and the pin that it is riding on.With the pin removed sometime the float swells up,so you need to put the pin in and see if it moves.sometimes the float will not move on the edges so you need to file/or sand paper the edges so that the float moves freely.

Sometimes the float bowl gasket catches on the float and stops it moving freely happened to mine on my old Indian GP

So I ordered the "red tip" float valve, but it was the wrong size it wasn't tall enough and consequently wouldn't seal properly at all.

However, I noticed the float valve that was in there already had the red tip, and looked somewhat new ish anyhow. Perhaps the previous owner had already replaced it?

Either way, the main thing I discovered is the pivot pin that goes through the float and holds it in place wasn't quite smooth, it had some divots from being removed and replaced. Consequently, it would sort of hang up and stick the float in the up (sealed) position. I think THIS is what was causing my starting problems.

I sanded the pivot pin down quite a bit so that the float moved totally freely inside the bowl. No starting problems now, and it's been quite a few days of riding!

Hey all,

I thought I had my problem solved, but this morning I had the same issue again. What's weird is it ran great for like 6 days, but just started having problems again this morning. Same as always, would not start, but I was able to bump start it down a hill. Super frustrating.

To recap: I have a Jetex SH2/22. I have a red-tipped float needle, which like previous posters said, doesn't mean it's impervious to unleaded fuel.

I ordered this item - https://www.casalambretta.us/Dellorto-f ... %09J200859 but the float needle was not tall enough and would not seal at all, so it's not the right size. I'm gonna check with Casa to see if they sent the wrong item by mistake. Did I purchase the wrong item by any chance?

While I was in there trying to get the float needle to work, I noticed my float kinda sticking in the up position due to the pivot pin being kinda divoted. I filed that down to smooth it out and it seemed to move freely, so I thought perhaps that had solved my problem, but maybe not. Perhaps I'll dig into that again.

One potential workaround or test would be to always turn my fuel valve off before I stop the engine, so the fuel in the bowl is exhausted and the float cannot get stuck in the up position. I guess I can try that for a while and see how it goes.

You ordered a Dellorto float needle which is different from a Jetex one, check out the link below

http://www.scooterrestorations.com/lamb ... dle-jetex/

I would replace the needle, float, float pin and gasket as one and see how it goes then

The issue appears to be 'hot' starting & that is not unique to Lambrettas fitted with certain Dell'Orto carburettors or the replicas.

Lambrettas with their fully enclosed bodywork have nowhere for the residual engine heat to go, so the carburettor is one area that soaks it up. The carburettor is fairly cold when running due to the process of evaporation, so the fuel remaining in the bowl expands a lot.

Unfortunately the SH has no bowl mounted overflow, just like the very popular PH. There are not even pre-cast mouldings in the bowls to retrofit overflows, unlike the VHB, for example. If anything, the air filter hose may excaperate the issue, being coldish upon stopping, then warming up, then cooling again. That is likely to draw fuel into areas where starting will become an issue. Think of it as a kind of capillary action.

If I were you, every time that you ride your scooter, whenever you decide to stop & park up, run the carburettor dry. That is, turn fuel off & let the engine idle until it conks out.

Let's see how you go. Not rocket science, but @ least it should verify the issue.

jettex has a float bowl gasket that dellorto does not have; some of the Jettex float bowl gaskets are slightly too big and can catch on the float ive seen it on a couple