LCGB Forums

Sh2/22 carb on my gp keeps getting petrol coming out of the overflow holes. Changed float and float needle for new ones yet it still keeps coming out. Any one have any ideas what else could be wrong?

The float could still be sticking inside.

Take the bowl off, hold the float up lightly with your finger and turn the petrol on. If it still flows the problem is the needle. If that stops it then the float is sticking in the bowl. Check it moves freely and remove any 'flash' from the moulding.

There's more than one length of needle - is it the right one?

Is the SH2-22 a Dell'Orto or Jetex?

Float sticking problems seem common with Jetex. This Forum (Search) or the Internet has loads of owners saying about the problems so might be worth a look....

Black tipped needles are not ethanol proof so deteriorate and cause flooding. Change to red tip. Make sure needle valve seat is 100% free of debris.
Paul

I had a continual problem with my SH2/22 for the last year. I went through several different floats, pivot pins, needle valves and lots of general dicking about. I managed to sort it in the short term but the problem always came back. I suspect that the original Dellorto floats swell a little in modern fuel containing ethanol. My salvation was getting one of the remade Scootopia floats. They are about half a millimeter smaller and hence do not foul on the float bowl. Since switching to one of these, I've had no recurrence of fuel pouring out of the overflow or the mystery poor starting that was probably caused by flooding. The best £4 I've spent on a Lambretta part.