I just bought a YFZ450 from a buddy, there is a problem with it already. The bike sat for almost a year in a garage, when I bought it my boyfriend changed the oil, and other fluids. I took it out for a ride and it ran great for about 5 minutes, then it shut off. Brought it to a shop and they told me radiator wasn't working (fan wasn't turning on, hose ice cold, etc...), turns out it had a blown head gasket??? Coolant was leaking out of exhaust. Well we got it back from the shop, guy said it should run good now so we decided to take it out for a ride, ran good for 5 minutes then as soon as I pulled in the clutch, everything shuts off inluding lights, it's like someone unhooked the battery. It starts back up, but then it just putts out, it runs if you give it gas, but as soon as you let off the gas it just shuts off... does anyone know what could be wrong with my new bike??

 

Double check all the wiring connections.
Clean the carb.
Do a compression test.
What does the plug look like?
Radiator fan plugged in?
Might be the temp sensor on the radiator.
What color is the exhaust?

More than likely it was failure of the temp sensor, fan, or water pump that caused the blown head gasket.

Not to dis your man but any chance he messed something up when changing with radiator fluid?

 

I broke down and took it back to the shop, it turns out it was the stator. Just more money out of my pocket. Thanks for your help though!

 

no problem, thats what were here for [img]i/expressions/face-icon-small-smile.gif[/img]

 

Electrical Issues on the 450 2004-2006
According to article in Quad magazine (March 2007), the charging system doesn't properly charge the battery when the headlights were not used. Yamaha fix in the form of a resistor kit that "puts a slight drain on ignition system, forcing charging system to operate at all times".
Still complaints, no real fix yet.