Modern Vespa

A little history: got the old VBA running a week or two back. Engine was running smoothly. Couldn't ride because of clutch washer issue and broken fuel tap. fixed fuel tap. Installed new clutch washer.

Now it's hard to start and when it gets running, I have to keep it at wide open throttle to stay running. It runs but at WOT it revs up, dies down, revs up dies down, revs up dies down and then dies completely, then it acts like its flooded, and after waiting a while it will start again, but acts the same.

Seems like an air leak, but what changed. Could something related to the clutch change be causing this?

I know I really just need to split the case and do a rebuild, which I intend to do, but dammit I just want to take a little ride first.

Any ideas?

not an air leak!

An air leak would run really fast with the throttle closed.

How's your float needle, have you changed it?

must be too old buy an lml

I agree w/ Patrick on the float needle -- pull the float assembly out and see what's up. Any fuel leaking from the carb down the clutch-side of the engine?

But you changed the tap out, too, right? Maybe double-check the hose -- not just hose length and kinking, but for sediment that might've gotten dislodged when you were working. Heck, blow out your filler cap breather holes too, just to be sure.

Cool, I was hoping fuel flow. I guess I got my air leak symptoms confused.

I removed the fuel line at the banjo and it seemed to be flowing well, but I will check that again. Fuel line is 24" long. I ran it with the cap opened to rule out gliged holes and it still did it.

I'm pretty sure the needle was OK, when I cleaned up the carb. It looked like someone had previously done a rebuild on it. It was the red tipped kind. The rubber was soft. I'll recheck it though. I have an extra needle. I'll just swap it out while I'm in there.

I'll take a look for gas leaks. I wouldn't have noticed yesterday since I had gas all over the place. It should be dry by now.

Thanks all. I'll report back with findings.

Ok definitely fuel flow issue. I replace the needle, blasted the carb really well and it was running smoothly... For a while. Now it's pretty much where it was before. Obviously I need to give the tank and tap another good rinse.

But, while I was running this was happening: Engine dies when I pull in the clutch lever. VBA

If you didn't replace the needle, it needs it!

That may or may not be the cause but it needs doing anyhow.

I did replace the needle. I had a fresh one on hand.

One thing I didn't do was check the sediment bowl in the tap.

I'm joust going to give the whole fuel system, tank and all, a good cleaning... again.

I had a similar issue with my vbb. It ended up being a warped float bowl. I had to take it to an expert because I, for the life of me, couldn't figure it out. I would have to have it at WOT to start it. He told me to change it, I did, and never had the issue again.