Maximum horsepower XJ550 reciepe

I just picked up another 81 that I want to turn into an AHRMA Middleweight Superbike. I went to the local race and saw the competition. I feel I need at least 70+ RWHP. The winning GPz550 makes over 80 out of a 615. That's his small displacement motor. :cry:

I'm allowed a maximum displacement of 685. I can use aftermarket cams. I can use round slide carbs.

I have some NOS Yoshimura cams that must be close to 30 years old now. I have access to some Keihin CR29s.

Can I use FJ600 parts? How about a whole FJ600 top end on the XJ550 bottom, with a big bore kit, worked head, and the Yosh cams. Feed it with the CR29s. :evil:

Anyone ever built a large displacement Seca 550? I think I recall one member here that has.

I'd appreciate any input.

 

what are the specs on those cams? megacycle makes some cams for these engines as well, they may have a hotter setup? not sure just throwing it out there.

 

I have done what you are trying to do. For me I installed a FJ 600 engine and bored it out and put a wiesco 652 piston kit in it. I used stock carbs but aftermarket are definitely do able. I also degreed my cam's but couldnt tell you what they were. Make sure you are able to update and do as much as you can for the suspension. That will help out lap times more than a larger motor will. I spent 1200 on building the engine and only gained a half second. I upgraded to a different front end and wound up dropping a second and a half. I think I wound up using the FZ 600 front forks that I was able to use different springs. I also have a very trick Cal Fab braced swingarm that was pretty nice also.
Keep us posted on what you are doing. Always like to hear the seca's out there kicking the snot out of the GPz's

Sean