Modern Vespa

Gents:

I could use some help troubleshooting a problem with my '64 Cruiseaire. She starts well, usually on the first or second kick. When accelerating from a stop, especially on a slight incline, I need to increase the RPM's to 3000 to 4000 and slip the clutch in order to get the motorcycle rolling, otherwise it stalls. Otherwise, performance is as it should be.

I have ultrasonically cleaned the carburetor and all the jets are stock sizes and OEM. Idle is set to ~1000 rpm. Confirmed good fuel flow from petcock. Fuel filter is clean. I have set the ignition timing at 24 BTDC (static) and the points gap at 0.5 mm. Spark plug is an NGK B7HS gapped to 0.6 mm but are black in color. Pilot air screw is at 1 ¼ turns out. The cylinder has been honed and new rings have been installed. The muffler has been BBQed. Fresh Motul 10W30 Transoil in the crankcase. The air filter is stock and clean. HT wire and spark plug cap is new.

Any insights would be greatly appreciated. Cheers.

Idle seems high, kinda tough to set up correctly when it's this high. I'd use a Bosch copper plug for this bike. Nice write up tho.
W8AC

Your idle is same as most of mine and a normal NGK plug should be OK, but you might try retarding your timing. It seems to be out at the end of the recommended range on the chart I found at BeedSpeed to confirm, and there's also this: https://beedspeed.com/en-us/pages/vespa-standard-ignition-timing

That's a low idle from where I'm from.

Is this a new behavior, indicating something changed, or you just want to "fix" the issue?
Your stock bike simply doesn't generate enough power at less than 3-4K RPM's to get you moving on a hill, which means the only way to "fix" it would be to put a more powerful top end on it, which it sounds like is not the direction you want to go.

Retarding the timing will probably make the issue a little worse, if anything.

This is a new issue that I am working to resolve. I currently need to be at 1/2 throttle and slip the clutch to get rolling at all. Even on level ground. I almost think the clutch is binding?

Random-ish thought, but make sure your jets are all tight in the carb.

If the main stack has worked its way loose, it might have richened things up to where you're losing the lower end power.

Thanks, I'll give it a look.

Have you checked the GEARBOX OIL?
was it NOT USED for a long time?
- if not used, could br that CLUTCH PLATES are sticking together

I checked the jets. All nice and secure. Any yes, I too think it might be clutch related at this point. Will dig into it this week. Thanks.