engine case swap

[wayne billings]

hi i have a question. i am considering swapping the top engine case( block) from an '85 to my '86. with bearings being limited to what yamaha sells, does anyone know if there are things to look out for or problems that happen when this is done? any and all input is helpful. thank you. blessings to you. wayne billings

 

[Fire-medic]

I know Sean has mentioned doing just-this in the past, but my understanding is that when the cases are align-bored, they should then be used as a matched-pair. I suppose if you had two different pairs of cases, and the bearing codes were the same, you should be able to swap-'em. Better take multiple plastigage measurements on those bearing cups to ensure that you have proper clearances around the circumferences of all bearing surfaces.

 

[one2dmax]

I have commented that though it has been done before it's not even remotely suggested! It's a good thing Yamaha knows how to keep tight tolerances.

 

[Fire-medic]

I have commented that though it has been done before it's not even remotely suggested! It's a good thing Yamaha knows how to keep tight tolerances.

Just because you can, doesn't mean it's a long-lasting repair. I'll join with Sean that it's not the best idea, though I have no expertise as anything like being a machinist.

 

[DreamV4]

cases are align-bored,

!!!