My XJ650RJ Seca

I have had my xj650rj for 20 years now and love it. It has a 4 to 1 yosh pipe and a high flow filter in the air box. Other than that it's stock.
I was wondering if anybody has played around with cams from a 750 to a 650 and jetting?
Am I asking for it? or should I just put a 750 into her?
I NEED MORE NUTS.

 

Swap in a 900?......Dont know if it would fit, just a thought.....Maybe a 1100..... 8O

900 crank, rods, cylinder & head in the 650 cases?....... :roll:

New to XJs so not sure what fits what with the shaft drives. Learning bout the chain drive units tho.......

Should be interesting where this thread goes........

Come on Gearheads, whats it take to light one of these Dinosaurs up?




Yep..........I'm a stirring the pot :twisted:

 

What you need then is a YICS motor; and if you're going to swap motors, why not a 750?

A 750 Seca motor should be a nearly direct drop-in.

 

Thanks so much for your input guys it's awesome.
I will see about a 900. I like the idea if it will fit.
I shy away from the yics models just because I don't have the blank off tool needed to lock off the cross drillings and sync. the carbs.
I have access to a sweet set of syncronizers and with the non-yics motors
it's a piece of cake to dial them in.
Is there a big difference in torque between the yics and non-yics motors?
Thanks again for your input guys. This site rocks

 

The 900 will be too tall, from what I understand, for that frame. We know the 750 will fit, because that bike was sold with the 750 motor (some Canadian models.)

The YICS passage can be blocked with as simple a tool as a "rope-rolled" rag soaked in oil; or a proper reproduction tool can be got for around $40.

As far as torque, HP, and powerband "placement" the only real way to tell would be to ride a YICS-motored bike back-to-back with a non-YICS bike of the same displacement and see. Yamaha's main claim for YICS was a 10% improvement in fuel economy and better low- and mid-range throttle response, by virtue of more efficient combustion.