Back-story: I recently purchased a 99 F4 and am rebuilding it. Overall the motor is in excellent shape (still even has crosshatch on cylinders). One issue I ran into is the last owner, in his attempts to clean the carbs after letting it sit for near 3 years with gas in it, destroyed a lot of the rubber parts in it. After looking at the cost of parts to rebuild/fix the carbs ($250-$350), it just isn't worth it. So I'm going to convert to fuel injection. Looked at F4i heads but they are running a premium right now ($250-$350), vs 600rr heads can be had for as little as $150. Same issue with the TBs, ECU, etc. so I'm thinking I might go RR parts instead.



Question: What exactly are the differences (if any) between the 600RR and F4i heads? Any reason I couldn't install a 600RR head on my F4 block?

Chris

 

Completely different motors, don't swap over in the least bit.

 

really? lameness. I thought the RR was just a high lift version of the F4i

 

RR's also have two injectors per cylinder.

 

But both are mounted to the TBs right (no injectors directly mounted into the head are there)?

 

If i were you I'd find a good secondhand set of carbs... just because it seems cheaper and easier.

 

Been looking all over. Because F4 (carbed) only went for 2 years, they are painfully difficult to find.

 

Okay, people keep saying the F4i and the 600RR are "totally different motors" yet here is a direct comparison of an 06 600RR cylinder head and my 1999 F4 cylinder head. The cylinder mating faces look IDENTICAL! At this point I'm willing to bet they will mount up and work. I found some on ebay for $50 shipped so I just might buy it and see what happens (worst case I'll sell it to the local motorcycle shop for $25).

update: Ran a search on HondaPartsHouse.com and sure enough, both the F4i and 600RR share the same cylinder head gasket part number. That confirms that the deck surfaces are identical (as the pictures indicated). I'll post my results when I get my head.

update #2: After further research, I can see why everyone says "600RR is a totally different motor," the motor case is WAY WAY different. Looks like the tranny almost sits on top of the crank (up and back vs just behind). It still however looks like the cylinder deck/head surfaces are the same (the above update where I mentioned using the same gasket). Makes me wonder how the 600rr case would fit in an F4/F4i?

 

Your being a cheap *** is going to end up costing you more money in the end. Enjoy.

 

I don't see where I'm being a cheap ***, I'm being practical. I don't feel it makes good since to spend hundreds of dollars fixing the carbs when I can invest that money towards converting to fuel injection. It will certainly cost me more in the end to go fuel injection, but if I would have spent 1/2-2/3 doing the carbs, I didn't really spend that much for fuel injection.

Chris