XJ 600 head swap to Fj 600 ??? - Head swap advice/proceedure?

Im pretty sure these are the same engine. Is there something I am missing? The part seller told me i needed a fj600 head and his xj 'probably wouldn't work'. I think it's the same engine no?

While you are here.... If I get a full working head from another bike that is known to be good and functional the swap process isn't that involved right? Basically remove the old one, make sure all the timing components line up, strap the new one on with a head gasket and presto? I have the manual and will follow all procedure, but that's the basic outline...right?

While its open perhaps i'll clean up and lap the valves in their seats, to improve any fitting issues, check everything over on the head side, but i would plan to leave the cylinders alone, as not to disturb any carbon deposits that could compromise the compression.

Is that about right?

 

The original question FJ600 to XJ600 head I have no idea about...
But I do know...
If you get a head from the same model it will be good to go, and even better will valve regrinding, lapping, valve seal replacements.
Not sure if that helps.

 

You have 3 bikes which can donate a head.
FJ600 obviously
YX600 Radian
FZ600 86-88

Yamaha labelled 2 different bikes XJ600.
The rest of the world our FJ600 was labelled an XJ600, essentially the same bike but you'll need to shop overseas.
The Seca II is an XJ600 I don't expect it will be compatible as it has downdraft carbs.

 

below

 

If i can just make this change for clarity sake you are saying....

You have 3 bikes which can donate a head.
FJ600 obviously (Fj600 = Xj600, but not Seca II)
YX600 Radian
FZ600 86-88

I think i get what you are saying, but just want to confirm that Fj600 is north american labeling for euro XJ600, which is the same bike with the same motor.

 

Correct

 

I dont see the cost (parts/labor) out weighing the performance gains, the valvetrain cant be that far different from the other?

why?

 

The parts are identical, shouldn’t be any performance difference.
@Phil B what is wrong with your head?

 

Between models the manufacturer can fix issues with valve seat angle, weak spring issues etc.. but this in no way will be any specific power increase. @Simmy im with you, whats the problem on original head/engine?
and if nothing... why the swap??

 

Basically me...I put in a compromised shim to do some testing until I got a hold of a good cheap one. It shattered during a test ride and shot a piece out of the head. Nice chunk flew out the back of the head toward the carbs.

Entirely my fault. I knew i was taking a risk, just didn't assign the correct probabilities. This whole restoration has been a learning experience, so let the learning continue! Surprisingly, i'm not nearly as mad at myself as I should be. Im almost amused. Perhaps some part of me is eager for the process to continue and deepen. I do enjoy the work, maybe even more than riding it, for now.

 

lol... that's the thinking of a mechanic.... pleasure in the inner workings of an engine..

sorry to hear that, you should have led with that info first...

 

@Simmy has the info you need.