As you might be aware, I'm rebuilding my F3 & thought about fitting an 08RR shock.
I've dry fitted it & can't really see any issues, why do people not fit them? Are there problems that I can't see?
There is plenty of room around the reservoir even with the expansion bottle fitted.

 

Well I would imagine the weight difference between the two bikes would be the issue. As the f3 weighs 470lbs and the rr weighs 370 lbs.

 

Now there is something I didn't think about, many thanks.
I am going to try it, it's an easy job to swap over to std, so will see how it goes

 

Do you have it all set up? Does the new shock make the bike's tail extra high?

 

It would probably sit lower I think

 

Haven't got any wheels on yet, just thought I would fit it to see. Will be getting onto it today after I have finished work. Need to get some new boots put on the Triumph, but have the whole afternoon to play with the CBR

 

You can compensate for this with more preload if necessary. I would take a measurement from the center of the axle to a fixed point on the frame with the stock shock. Afterwards, take a measurement with the rr shock. I bet you the rr shock is longer and will raise the rear end some. Raising the rear end could result in a smaller rake measurement and a smaller trail measurement. This sort of geometry will give a quicker steering response at the expense of stability.
Just so you know. If there is a difference of say 3mm between the two shocks, it will not equal a 3mm rise in the rear end. This is because there is a leverage ratio (X:1) due to the linkages in the rear suspension.
My guess with installing an rr would be clearance. You also have to remember that the shock compresses and extends and it could hit something during one of those motions. A good way to see if it's going to hit anything is to remove the spring and manually move the rear suspension from full extension to bottoming out. You could also calculate the leverage ratio while you're at it.