Pw 50 dies when warm

I have a pw 50 that dies when warm?? It's a fresh rebuild with all new parts, piston, rings, jug, stator, coil, carb, fuel pet cock, cdi, rectifier. It starts and runs great when cold and after 15 minutes or so dies! The sound of the engine even changes. Sounds like it is starting to load up/seize. Oil injector is working great but for trouble shooting purposes I am running pre-mix. Any and all help is appreciated.

 

I have a pw 50 that dies when warm?? It's a fresh rebuild with all new parts, piston, rings, jug, stator, coil, carb, fuel pet cock, cdi, rectifier. It starts and runs great when cold and after 15 minutes or so dies! The sound of the engine even changes. Sounds like it is starting to load up/seize. Oil injector is working great but for trouble shooting purposes I am running pre-mix. Any and all help is appreciated.
 

Float height set to spec or slightly below?
5 minutes ago, HeavyRotation said:


Float height set to spec or slightly below?

Spec I think. Not sure how to change that?

Check that the exhaust pipe isn't clogged. 

Check that the exhaust pipe isn't clogged. 



Not clogged.

Crank seals

Crank seals



New, both sides

Put the old carb back on.

Put the old carb back on.



Unfortunately that's not an option.

Verify the float height before messing with anything else.

Verify the float height before messing with anything else.


How do you confirm float height? Also I was asked to check my squish gap. Is that a big deal on 50cc?

Give the carb a good cleaning.  Make sure the needle seat is clean and check the float height.  Make sure the choke plunger isn't sticking and clean the pilot jet.  Verify the main jet size and needle clip position.  I've never had one apart, but that's what the diagram shows.  Manuals are available free online if you search.  

https://www.partzilla.com/catalog/yamaha/motorcycle/2002/pw50-pw50p/carburetor

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