XS360 and XS400 motor swap

[Phoenix]

That's not at all what I heard.

I'm jumping into the garage right now to prep tank and take out the carbs and bolts and clean. Worked on an xj before, but never with a yics before. Gonna be a deep clean....

 

[xschris]

Well it's a fact. 77-82 SOHC bikes/motors and 82-84 Dohc bikes/motors Don't interchange. The 76-77 xs360 and the 77-82 sohc xs400 do. Yamaha made both sohc xs400 and dohc xs400 in 82 so don't confuse the two bikes.

 

[BIFFEDIT]

So....back from the dead?

Can I swap an xs400 head complete onto an xs360?

Can I do a big bore kit on the 400 head and still bolt it on the xs360 bottom?

 

[tstidham]

It will probably bolt on but you'd want to verify the combustion chamber sizes are the same. My guess is the 360 would have a smaller chamber for the smaller piston. And in that case you'd lower the compression ratio and make less power. Machine shops use a calibrated water tube with cubic centimeter markings, level the head on a flat surface and with the valves and spark plug installed, fill the combustion chamber and measure how many cc's of water it holds.