Piecewise engine building?

[Kirk Feldkamp]

Hey guys,

I was asked a question today that I didn't have any experience with, and figured someone on here would. The question is whether or not it's possible (and recommended) to mix and match case halves from different engines of the same model and same year. The engine is question is a 2001-2003 GSXR 600, so it has normal hydrodynamic bearings for the crank. I'm just not sure how close the manufacturing tolerances were, and whether or not the crank journals will likely be concentric enough to use without honing them again.

-Kirk

[Kirk Feldkamp]

Hey guys,

I was asked a question today that I didn't have any experience with, and figured someone on here would. The question is whether or not it's possible (and recommended) to mix and match case halves from different engines of the same model and same year. The engine is question is a 2001-2003 GSXR 600, so it has normal hydrodynamic bearings for the crank. I'm just not sure how close the manufacturing tolerances were, and whether or not the crank journals will likely be concentric enough to use without honing them again.

-Kirk

[Markus]

I have only little expertice on engines but my bike (ZX6R 03) service manual states that the crankcase halves are machined together and shouldn't be mixed.

I'm pretty sure this applies to most of the bike engines as it's considerably cheaper way to manufacture the cases and thus I doubt the mixed cases match well.

[MechanicalChris]

It's not advisable as others have said, but....

Put it together and measure it. If need be, tunnel bore it.

There are plenty of "do's and don't s" when it comes to engine building and while this is one that I wouldn't do if I could avoid it - some can be worked around and some can't.

[AxelRipper]

Not very familiar with that engine, but it depends on the construction. Do the case halves form bearing surfaces (Crank, cam, trans, some other random shaft)? If so, then it is definitely not advisable to mix and match parts. They're assembled at the factory and then line-bored to make sure everything is true.

[rallygabe]

I would side with the Nay-sayers.

is it possible? sure. suggested? NO. I'm guessing a new case would cost about as much as the machining?

[Gruntguru]

Although I would also side with the naysayers, as MechanicalChris says "Put it together and measure it". I have been surprised many times by the accuracy of Japanese bike engine components.