01-02 YZ250F crank, rod and rebuild

frankfilm

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#1
Hi,

I'm considering buying a 01-02 YZ250F for trails and super moto.

I live in CA, so a green sticker is important.

I plan to have the motor completely rebuild by Forward Motion. My concern is the crank and rod assembly. Can it be replaced with a 03 assembly?

I am new to dirt bikes. So, any info will be appreciated.

Thanks,
Frank
 

bclapham

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#2
why are you concerned the crank is worn in the first place????? how is the 03 superior to 01-02??

if you want to replace them call motosportoutlet they have a smoking deal on a complete wiseco crank/bearings and seals package!!!
 

frankfilm

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#3
Hi,

I read this thread and got concerned.
Thumper Central ยป Broken Cranks on YZ250F and WR250F Frame #'s

As far as the differences between the 01-02 and the 03, a member listed these specs.
2002 2003
Crank Web 105mm 106mm
Crank Pin 30mm 32mm
Bearing 38mm 40mm
Crank Taper 17mm 20mm
Crank Length 95.5mm 106mm

Thanks for the motosportoutlet info.
Frank
 

Rich Rohrich

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#4
Frank - The replacement rods & bearings from Yamaha have not been a problem in a properly rebuilt crankshaft. It's important to carefully check the machined journal that mates with the main bearings on the ends of the crank . Once these journals wear the crank can't be rebuilt. The only option is to purchase a complete crank assembly. If you are going to run a used 250F at sustained high speeds like you'll see in SuperMoto it would be wise to figure in the cost of a complete bottom end rebuild as well as servicing the cylinder head. The titanium valves are only good for a couple of seasons before they start to pit and cup. The seats can be serviced by a good machine shop but the valves are unfortunately disposable.

It's a great engine/bike package, but they need to be maintained on a schedule similar to a 125 two-stroke.

Good Luck.