Blown engine, melted piston and broken valve... By ragtopdodge (Read 744 times)

[ragtopdodge]

What would cause all this?

Running lean?  Shoot, the engine was running perfectly; didn't think I was running THAT lean.

Always ran it using Premium fuel.  Plenty of oil.

[ragtopdodge]

Yes, that's the valve head stuck in the top of the piston.

Nasty, huh?

[skyrider]

My guess is that the valve stem broke off and all of the other damage is the result.

[ragtopdodge]

Hmm...ya, but would it cause all that heat for the piston to melt like that?

[alleyoop]

It was running hotter than a skunk, really Lean. I know folks want speed and running lean creates more power but you pay the piper sooner or later. Always give up a little power on the top end and run a little on the rich side. You run motors Lean on the top end at high rpms and things like this happen. Some even the rod breaks and punchs a hole in the case.
Alleyoop

[ragtopdodge]

What's the best way to adjust the mixture? Enrichen (screw turn counter clockwise) as it starts to idle rough?

[alleyoop]

Follow this step by step procedure:
Alleyoop

thescooterprofessor.proboards.com/thread/3001/4-stroke-carb-tuning