Vespa Grande flooding?

My bike runs good when it starts initially, but after a couple blocks at full throttle floods and doesn't want to start again for a while. I've jetted down a couple times and I'm back at the stock 66 jet. It runs great at half throttle like it would all the way on. It's a stock engine with a Dellorto 13.13 and a Proma circuit pipe. Would I just keep jetting down until it stops or could it be something else?

Re: Vespa Grande flooding?

Double Trouble Dan /

dirty or bad float needle

Re: Vespa Grande flooding?

kim jensen /

Are you sure its flooding? That would be caused by your float needle not sealing off the gas flow into the carb. Does gas pour out the carb when it is not running and the petcock is on? Otherwise if it quits after running at WOT for a few blocks and then won't start for a while it is most likely you gas cap not breathing in air and you are running out of fuel. Try with the cap loose and then clean the air breathing passages in it!

Also sounds like a big jet for a 13-13 on a stock cylinder. I run 66 on my 15 sha on a kitted Moby. Depends on your altitude as well though.

Re: Vespa Grande flooding?

kim jensen /

Stock jet on a 12-12 is a 52, on a 12-10, 49. So jumping to a 66 for a 13 carb seems too big.

On my bored and ported stock Grande with a bored out 12 carb I ran a 54 jet. If you need that much bigger to make it run you have airleaks. Check the gas cap and go down to a 56. If you have access to a leak down tester , do that.

Re: Vespa Grande flooding?

Dirty30 Dillon /

66 is wayyy hi.

Sounds like your bogging out and fouling the plug, not flooding.

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