MOPED ARMY

That's a good idea, I'll give that a shot. Fuel seems to be flowing just fine, no fuel filter. When I feel it cutting out I've just come to a stop and let the float fill back up and the. Turn around to the shop and it just does the same thing

It's been a long time since I had a Moby w/ PHBG, but I remember a couple of tips I heard to improve fuel flow. Moby 70cc+ engines tend to be very 'buzzy" with vibration so the spring loaded needle was recommended to me and I think it did help my build.

Also the "metal disk" mentioned in the Wiki is another potential factor. Try removing it if you are using it, or if you are not using it maybe try opening up the holes and running it to see if there is a difference.

"It sits between the main jet and diffuser tube. It was designed to break up air bubbles in the fuel when high vibrations cause foaming within the carburetor Bowl. This help prevent air bubbles getting trapped within the fuel metering system which would cause an extreme lean condition under high throttle power demands. Many have removed this disk because the new fuel which has been developed has different properties of tension thus it tends to trap the air bubbles underneath the apron causing extremely lean conditions under high vibration modes at full power or close to it. By enlarging the holes in the disc will allow the air bubbles to flow through this mod must be done especially if you're running fuel with any alcohol in it and most new fuels due to the difference in the chemical blending from when this device was originally designed to work with the fuels properties of tension.

I have found that running carburetors that suffered from heavy foaming that by reinstalling the disk with larger holes assisted greatly with breaking up the bubbles and causing them to move away from the main jet pocket under the desk."

Similar setups have known foaming issues as stated above, which cause breakup under load/throttle, then ride just fine.

What's up with the motor mounts? Is it a washer with a conventional rubber mount or did you do some kind of custom aluminum hard mount thing?

Motor mount issues can make the foaming really bad. Usually spigot mount carb it's not a problem so much, but who knows. Every kit, crank, variator, intake is going to have a different vibration.

Putting the big washer over it basically negates having a bushing still all. You’re gonna snap those rusty motor mounts off that frame for sure.

What helps the rubber not rip is setting the correct preload on the engine bolt. You know, just because you have built a bunch of bikes doesn’t mean you know what you’re doing. I have worked on thousands of mopeds and still learn new stuff every day.

Not saying I’m above sketchy fixes, but with mobys, especially tuned ones, you have to dampen all the vibrations. Like even using silent blocks to make a support for the spigot carb mount to mount to the case and rubber hose to mellow the spring rattle, don’t forget to lock wire every nut too! Otherwise you end up with a buzzy-rattle trap that’s main purposes is ejecting hardware and foaming fuel. (edited)

put a polini cp carb on so much easier to tune. and that is the strangest variator weight set up I've ever seen but hey if it works. I also set the le partie at 1.5 and higher rev bikes normally need a colder plug i run a ngkb9hs. now go tinker have fun hope it helps

Oh fuck 1.8 is a lot of timing, I usually start around 1.1mm. If you’re using the included parmakit head too the compression ratio is bananas, you’re gonna need to turn it out and get that compression down to about 140 or so.

I have solved the same issue on many bikes by:

1: I install a new plug

2: Remove and remount the exhaust. Nine out of ten times a slight leak at the header opens up at higher speed dropping back pressure and killing the revs. It feels as if you run out of gas but once bike is brought back to idle, you can start riding again until pressure builds then drops off.

3: Increase your variator weights