50cc dies to 10mph when engine hot

[skyrider]

Thanks for responding! I took out the original plug and replaced it with the same NGK ER9EH($15). Torque driver meaning the pulley for the rear part of the belt under the clutch housing? So remove the fly wheel? All the youtube vids are in spanish. So would I need to just relube the inside of the pulley? The only other thing that I could have done was overtighten the driving pulley after putting in new rollers but I followed the manual "tighten the lock nut to 20NM then a final 90 degree locking" meaning I tightened it 90 degrees more. (But I've overtightened that nut on my Chinese scoot and never had a deceleration problem before.)

[sc00ter]

If its the torque driver, rebuilding it can be a PITA but sometimes they need a re-grease. And the reason I asked about the spark plug, bootleg plugs are a annoying problem. We got a batch of NGK bootleg plugs awhile back and they were causing a slight lean seize issue. Now realize these plugs were being used in temperamental 2-strokes that love to seize if given the option-but these plugs drove us crazy until we figured it out. Ugh, my eye twitches just thinking about it! I've never worked on a Piaggio 4 stroke 50cc, so Im not aware of any issues with them, things to avoid, things to look for, etc. Im to far away to take a look at it myself but $120 seems fair to trouble shoot it if you cant figure it out. If you do decide to try the no muffler test, keep it to the bare minimum of miles! Your neighbors are gotta wanna pop your tires and the exhaust pulls heat off the valves and out of the cylinder, so shortest possible runs only! It also might run slightly different without the exhaust because the back pressure will be obviously missing. Post your findings when you do figure it out!

[sc00ter]

I just thought of this. If the belt was slipping, did you replace it? If not, does it measure in spec? If the problem is transmission related, it could be a torque spring. The torque spring is the big one behind the torque driver. The 3 clutch springs might be involved also. The low miles on the scooter is whats throwing me off.

[skyrider]

so here is the hose:

air hose.jpg

[sc00ter]

It could be just a overflow hose. For fuel spills during fill-ups or for the carb if it falls over. I dont think it has any importance to the problem your having. Where does the hose end? Vacuum hose for fuel flow? I dont think it would even start. Is the fuel tank below the carb or above it? I have no idea what model you have, plus the only Piaggio I know is my Liberty 150 and it has EFI. Im wondering if you could be getting vapor lock. Next time the scooter dies out, quickly loosen the gas cap and see if it 1: Makes a hiss noise. and 2: Starts right back up after the cap has been opened. I had a old car that did vapor lock at random. Annoying and embarrassing. I just drilled a tiny hole in the top of the fuel cap. You could also do a plug chop when it dies and see if its lean. White colored end is a lean sign, it should be coffee colored. I dont think thats the issue though.

[sc00ter]

Looking better at the picture you posted I think its just a fuel spill hose. Makes sure the fuel goes to the ground and not onto something hot.