Carb Problem

david · Post by **david** » Sun Jul 21, 2013 8:06 pm

My Jetex carb in the Silver Surfer seems to be leaking fuel near or at the float bowl. The scoot seems starved for fuel when at steady 1/3 to 2/3 throttle.
Put in a new float bowl gasket and it seemed to run ok for a day or two, and then same problem.
Put in a new fuel filter and cover gasket, still leaks a small amount of fuel, and runs rough.
Any thoughts before I pull the carb for a fourth time?

nick · Post by **nick** » Sun Jul 21, 2013 9:09 pm

I'm no expert. But if you do end up pulling it apart possibly check the float needle. I'm not sure of how the lammy carbs are, but possibly the float height is out of spec? Just guesses on my part.

big 3 · Post by **big 3** » Sun Jul 21, 2013 9:46 pm

first thing is first, give the carb a good cleaning, then inspect the float needle for signs of wear (usually indicated by a distinct line around the needle) and replace BOTH the needle and seat, once everything is installed, before putting the carb back on, allow the float bowl to fill to make sure the needle is sealing. Usually there is a screw on the bottom of the float bowl, attach a tube to the drain hole, make sure the end of the tube is higher than the bowl and loosen the screw, the tube will fill up with gas and you will be able to see how high the bowl is filled, adjust the needle accordingly if the bowl is not filling enough

jbcollier · Post by **jbcollier** » Mon Jul 22, 2013 6:34 am

No screw at the bottom and no replaceable fuel inlet seat.

However, there have been problems with different length needles. The "short" ones either barely work for a short period, or not at all. Do you have a spare needle?

jbcollier · Post by **jbcollier** » Mon Jul 22, 2013 6:42 am

And too long ones can cause fuel starvation at high speed:

http://www.forums.ilambretta.com/viewto ... 1&p=281626

Angelo · Post by **Angelo** » Mon Jul 22, 2013 11:14 am

If you don't David I might have one. I just need to look in my tickle trunk...

david · Post by **david** » Mon Jul 22, 2013 6:40 pm

Thank you all for your help.

I don't have a spare float needle but will order one. Scooter Restorations only offers one choice for float needles. (hope it's the right length!)

Thanks Angelo, if you have one, that could get me on the road much sooner.

Angelo · Post by **Angelo** » Mon Jul 22, 2013 10:11 pm

david wrote:Thank you all for your help.

I don't have a spare float needle but will order one. Scooter Restorations only offers one choice for float needles. (hope it's the right length!)

Thanks Angelo, if you have one, that could get me on the road much sooner.

I have a brand new Black tip Casa Needle. Let me know how we can get this to you...

david · Post by **david** » Tue Jul 23, 2013 6:55 pm

Thank you Angelo, it looks like I need a red tipped needle but, will pull the carb and see what's in there and let you know.
From what I understand, the black tipped needles can be or, are longer(???) and more sensitive to unleaded petrol.

Angelo · Post by **Angelo** » Tue Jul 23, 2013 7:05 pm

david wrote:Thank you Angelo, it looks like I need a red tipped needle but, will pull the carb and see what's in there and let you know.
From what I understand, the black tipped needles can be or, are longer(???) and more sensitive to unleaded petrol.

No problem. If you change your mind let me know...

david · Post by **david** » Wed Jul 24, 2013 10:12 pm

So, my Jetex SOI 100 carb has a Red tip float needle, ordered one on Monday. No riding this weekend but, maybe next....

Thanks for the offer Angelo, much appreciated.

jbcollier · Post by **jbcollier** » Thu Jul 25, 2013 6:07 am

It was working before, it should work again. Are you in this evening? I might be able to swing by.

Angelo · Post by **Angelo** » Thu Jul 25, 2013 7:25 am

I can check one of my spare Dell"orto carbs and see if there is a Red tip in one of those. I'll let you know...

david · Post by **david** » Thu Jul 25, 2013 6:11 pm

Would it be better if I stopped by your place John?
I am home for most of this evening though