Can anyone give me some details on the differences between the two frames. Other than the fact that the f4i is aluminum and th f2 is steel and the subframe differences. What I'm looking for is the difference in shape, dimension, and mounts for the swingarm. If anyone can help I would really appreciate it.

 

The sheer thicknesses are different in the walls of the frames, I think
in terms of shape, they're TOTALLY different, the steering geometry is wildly changed, and I believe the F4i motor is wider so you can kinda toss that idea out the door right now, and the mounting points for the motors are likely significantly different.

 

It's not the motor I'm wanting. It's actually the swingarm. And my f2 is stripped to a bare frame with the swingarm and forks on it right now. I'm thinkin about buyin an f4i swingarm for about 75 bucks just to see if I can get it mounted. Hell I got all winter to figure it out anyway. The one thing I'm worried about is the swingarm bolt size. I don't want to have to modify the frame in any way, but modifications to the swingarm would be no big deal. And in all actuality the motor is pretty much the same as far as mounting points and dimensions go. Or atleast for the f4 they are. I have an f4 motor that was in the f2 before it was stripped down.

 

With some light machining you can put a 600RR swingarm in there.

It has been done, and anything can be done if you know what you're doing.

IMO, not worth it though.

 

light machining of what exactly? frame or swingarm?

 

The pivots on the swingarm have to be narrowed, one pivot has to partially removed and pieces machined to be welded back on to carry different bearings, and a couple of tabs have to be welded on the frame.

This is what somebody told me that has done the RR swingarm from a 2006.

 

You could probably do a f4 swing arm into a f2 without modding the frame. The shock should bolt up as they both have a similar suspension setup. I'm not sure if 3/4" off the right side pivot would be light machining or not. I'm not too familiar with the f4 swing arm so you might have trouble getting that much off the right side (safely).The RR has plenty of meat on the right side pivot so your experience may differ. Reuse your f2 pivot bolt and have the f4 bolt bored out and used as a sleeve.

 

I could see it working. I got the swingarm in today and on of the guys that works at the shop with me is gonna help with the fabrication. He says we're not gonna have to machine to unbelievably much off the arm and it is pretty close to a bolt on mod.

 

The f4 and 600rr arms are the same pivot width. Trust me, it'll be ~3/4" that needs to come off if you don't modify the frame.