2007 Honda Metropolitan runs really bad

[otto-man]

Picked up a 2007 Honda Metropolitan with 6800 miles,(not a Metropolitan 2), that was stored for 6 years. Has new battery and obviously the carb had to be cleaned and new carb kit and float needle. Starts and idles like new. Everything works. Good throttle response but will not go over 25 mph.When warmed up, runs progressively worse. Valves are at proper clearance. Things I've tried: New fuel pump, new spark plug, new throttle position sensor(reset data per service manual), New bystarter, new anti freeze (bled air from system).Belt is good and brakes are working like they should. Reset data again. Gas cap is venting. It seems like something is telling the motor to slow down and then quit. Anything I missed?

[otto-man]

Tried known good stator, reset data.......no change.

[vintagegarage]

I agree, it doesn't make sense.. the only two things I could think of that would chance with the engine warming up are heat related. Overheating from lack of water circulating in the cooling system, or the bystarter stuck in the rich position (no voltage on the wires to the bystarter, or it is jammed somehow). I think nobody has responded because it sounds like you have covered everything. All I can do is ask questions. When the engine stops after slowing down and stopping, how much time has to pass before it will start and run at 25 mph. Lastly, when the engine stops, quickly turn off the ignition (and thus the fuel pump) and then open the drain screw on the carb float bowl and see how much gasoline runs out. Maybe the engine is stopping because the float bowl is empty.

[otto-man]

It doesn't seem like the cooling system is the problem. The radiator and hoses are warm after running for a few minutes and I get a few air bubbles when bleeding the system. Coolant light on speedometer doesn't come on (tested light and it works). After short ride at 25 mph, motor slows to idle and has barely enough power to move. Getting plenty of gas. If it was a 2 stroke, I would think it was a plugged muffler, but I've never seen a 4 stroke plug up that way. I'll remove and check to be sure. Ordered a new bystarter. The old one worked on the bench but maybe it's not working. I put it on "the back burner"for now until I can find a good metro to swap ECU. Just seems like something electrical is not allowing normal rpm's. Thanks for your help!

[FredB32]

Probably NOT the case as it's a newer scooter, but I finally tracked my issues to a bad ignition coil on the Elite 50 I just fixed up. Maybe something like that where it makes fine contact when cold but expands and loses contact once it's warmed up?

I don't know anything about the Metros though...

[otto-man]

I'll check it out. Thanks

[otto-man]

Tried 2 other ignition coils.....no change. Checked thermostat sensor....no change.