Looking for help 80's Yamaha 50cc

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Hey guys,

I am not a bike guy but cant say I am too bad at working on sleds and watercraft, so i am looking for some advice.

A friend of mine had an 80's model 50cc yamaha dirt bike for his kids. He said it ran good until a year or so ago. starts and runs great on the stand, but will not rev up under load. Will rev up perfectly with the tire off the ground but boggs and will bearly move with a rider on it.

any ideas?

Thanks!

 

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to the topidty for the morning

 

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nobody's got anything?

 

[grizzly se]

has the fuel been changed and the carb cleaned from sitting

 

[Bump]

has the fuel been changed and the carb cleaned from sitting

Well its not my bike and I havent actually laid eyes on it yet, but from what he tells me, it ran great up until a year or so ago and then this started happening. He said he's been through the fuel system and put in a new plug but thinks its in the clutching.

If I do end up helping out, I would go through it as I would with any "tune-up" / "elimination diagnosis" but was hoping someone would pipe up and say:

"oh yeah, that common with those. just do this and this and this and it should be good to go." :d

 

[chopper_dave]

I have one and it was a little slugish, so I pulled the pipe off and used a torch to burn off the carbon and oil. Worked fine for me hope this helps.