Tomos at full throttle stops abruptly, but quickly restarts.

I’ve had this bike since new and had the dealer modify it then by changing the exhaust and jetting. Top end is around 35mph. It was serviced last fall. Took it out today for the first time this year with a buddy. After about 5 miles, mostly at WOT, the engine came to a sudden stop. I was at full throttle at the time. In fact, it felt that the rear tire tire had locked up for a split second. Quickly checked a couple of things and started making plans for a tow. I tried to restart and a normal push on the petals resulted in a start. We decided that we might be lower on old fuel then we thought, and decided to return to home base. About a mile later at 25 mph - same thing. Again a complete engine stop and it definitely skidded the rear wheel for a fraction of a second. An immediate restart! I put the petcock on Reserve. Ran slower at about 20 mph and it again, it abruptly stopped. While coasting to a stop, I back pedaled and it started as if nothing happened! Ran okay at 15 mph for about 2 miles until we got home. I turned it off and removed the gas cap - I suspected a plugged vent - nothing noted. The tank was fairly full. The only think I can think of, is it possible a pre ignition could of occurred or inadequate full flow. None of my motorcycles have ever had a fuel pump, but I’m ignorant on my moped. The fuel is last years, but is alcohol free and had stabilizer added. The ratio is 50-1. Any thoughts? Thanks for the help. GS

Re: Tomos at full throttle stops abruptly, but quickly restarts.

Sounds like soft-seizing.

Re: Tomos at full throttle stops abruptly, but quickly restarts.

Really sounds like soft seizing but weird that it was happening at such slow speeds. I would start by replacing that old gas. But take the head\cyl off and inspect the piston\rings\cyl walls

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