Modern Vespa

I'm Back! I haven't been able to test-ride it yet...! I am dumbfounded by the
carb flooding. The carb has been taken apart and cleaned.

The timing was done by a static light and seems right. Firing at 24 degrees BTDC.

Everything ran 100% on the bench engine test stand and once in the frame it became very hard to start and when it did the idle was not smooth and bogged down at acceleration. Cleaned all the jets and the float moves properly. The pilot jet can be a 1/4 open or per spec 1.5 with no noticeable change. The throttle screw is down and isn't making any changes to the idle.

Maybe I need to go back and redo the timing.

Has a cable or fuel line been trapped during the install?

yep, could be a binding throttle cable, or the float needle and/or seat. Perhaps pressure from a full fuel tank is enough to push past the needle/seat, if its worn out.

There is really only one way an engine floods, fuel is leaking past the float valve. Have you pressure tested the needle and seat? Tested for a leaky float? Verified the float height?

I replaced the fuel hose with an OEM hose. The shut-off is also working properly. Now the next item down the line is the needle. It was replaced with a new needle and gaskets when it wouldn't start on the bench. It ran creating real excitement. Decided at that time to install the motor in the frame.

It ran very well until a "screeching" noise appeared. solved by a prior forum post just a week ago. It's become difficult to start ever since.

There is a restriction in the throttle cable, but it's like having the "cruise control" feeling stated by other members of this forum.

Regarding the float, I tested it by holding it down in a glass of water and it passed and wasn't replaced. It also is not capable of adjustment because of the design. It is solid plastic hinged to the pin. It doesn't have the typical metal arm for changing the height.

How do I test the needle?

Found plenty of info on YouTube regarding how to test a needle float valve.
Will be testing it in the frame and reply with the outcome.

I failed to mention that the throttle cable has full movement at the throttle control lever. Once the lever is released by to idle position, it slowly dies.
At the midpoint of the throttle, it idles. When I throttle up, it bogs and not capable of any advanced acceleration.

Taken the top bowl section off arrived to blow air into the inlet. It did not move the needle at all. I expected to see it move up and down due to blowing onto the inlet. Is there another test.

Alright, the test hole to apply air to check the movment of the needle is inside the filter chamber. The needle has free movment.

I don't see any way to adjust the float. I thought I read somewhere of a 17degree measurement. Don't quote me on that. Aren't needles unversal on this carb? I.e. 125 or 150 cc

I think the threaded hole is just for the screw. Fuel goes in the slot above it that's covered by the fuel banjo.

DAH... that's the most sense I heard all day. Haha

All passages were cleaned, open air/gas with a functioning needle.
Still no responses regarding the float, but as mentioned earlier, it can'e be adjusted.
I'll respond to all replies after I finish the carburetor install tomorrow.
The process is to move downline and hoplully will determine the problem of running too rich.

Check that the choke lever at the carb is fully closing.

Wow! Ray8, good call.
The chock lever was stuck open by an eight of an inch.
sprayed it with and cleaning oil and hopefully it will not be a problem again.
Thanks for the fix.

Motor cranked on the first try, there was a 50% improvement from before. It has sat for 3 days from having the needle and float inspected.
Now there seems to be another 40% process to improve it even more.

The rpms increased due to the lack of flooding for sure. I'm getting about half of the rpms it should be at. Its running smooth, no backfire or uneven firing.

I hope these short videos help.

I reset the timing to 24 degrees BTDC
Points are at .013

One is showing the throttle rod being opened to full throttle.
The second one shows and indicates the richness of the mixture, coming out of the exhaust.
1) https://www.youtube.com/shorts/fthJ3mBt9N0
2) https://youtube.com/shorts/YvxGQhSU334