When I rebuilt my 25/2 .
It has bushings and not roller bearings.
I ended up with several gaskets on each side to set
end play. What I found was that as I tightened the
bearing holder the clearance would change.
I spent a few hours tightening , spinning the crank by
hand, tightening the bolts, spinning the crank....
I think it is because the housing is so large the geometry changes
as the bolts are tightened.
Just what I found....your results may be different.
Edit....
I'm not sure I explained this as well as I should have. I'll try again.
What I experienced was not just end play but I noticed the entire bearing housing
would shift enough while tightening the bolts that the bearing would bind the crank.
I had enough gaskets on each side that my plan was to remove gaskets and "sneak up"
on the end play. As I got closer to the end play and began to tighten the housing bolts closer
to torque is when I began to notice the pattern on tightened bolts would determine bearing clearance.
And yes the crank is straight.
The fact that the bearing itself is some 3" or better in length must come into play.
It covers a pretty good area of the crank
unlike the roller bearings that cover what 1" or so ? So when tightening the housing bolts the housing
would shift enough that the housing was not parallel with the crank so the bearing would bind.
These engines are a hobby for me and not a job. I hate to think of the hours of time I spent on setting the
crankshaft into that twin. Time wise it was probibly over several weekends of play time. A few hours at a
time. I have built engines my entire life. Lawn mowers to race cars, boats, aircraft.......I thought I knew
something untill I discovered these monsters. They are a different animal.
I'm sure I could do one now in a few hours but don't know if I would want to !
I hope I explained this so everyone could understand what I'm trying to say.
Enjoy !