Cylinder head compatibilty

[Restless]

Are the xj and xs 1100 cylinder heads interchangeable?

[DiverRay]

Yes, but the XJ head on an XS may need to be check for clearance. I know some have done the swap, I just don't remember what, if anything, needed to be checked. A search should turn up more info.

[Restless]

Thank you for your quick response. I'm asking because I need a cylinder head replaced and the xj seems cheaper on ebay

[bikerphil]

If you use the XJ head with the XS jugs, you would have to somehow plug the YICS passage intake ports in the head. That would involve some machine work. Other than that, it should work fine.

[Radioguylogs]

You haven't shown any info on which model year XS.

FYI: I think the '78 and '79 XS heads have different valves and different cam timing than '80 and '81. I would expect the valves and timing for the XJ might be the same as '80/'81 XS, but someone here will know for sure.

[DiverRay]

The XJ and later XS had bigger valves, but lower lift cams. Also, the later bikes had a little lower compression ratio, IIRC. And Phil, good catch on the YICS! As I've not really worked on the late model bikes, I keep forgetting about that.

[bikerphil]

good catch on the YICS! .

Yep, I've gotten to know a lot about XJ's in the last few years, my neighbor has 2 XJ11's.

More info on the YICS ports...

https://xs11.club/forum/idle-talk-fo...ner#post216359

[Restless]

I have an 80 XS1100SG motor on an 1100G frame. I ran into an issue where I didn't tighten one of the bolts down good enough that attaches the the sprocket to the cam. It rode good for a trip to the local hardware store and back but when I tried to start her back up there was a clunk. Bent a couple valves. I was desperate to get on the road and with no money to put into a proper fix.. I pulled the valves(exhaust valves were the only ones affected) from the 1100G. They are a little shorter and I tried something that was brilliant in my head but catastrophic for the cylinder head. If anybody wants a picture of a piston that has all but desentigrated I will post them. So that's where I am now. I need a cylinder head with valves and I see one for a XJ1100 that is significantly cheaper than any for the XS

[Tonyxs11]

I think for piece of mind I'd pay the extra for the XS head then you know its right and a strait forward fit.

[Bonz]

82 XJ head should swap right onto the 80SG engine, valves and cams are the same to my knowledge, ergo pistons should be the same as well with respect to valve pockets/piston to valve clearance. To sync the XJ carburetors, the YICS ports needed to be plugged. Which would tell me to simply plug those ports on the head and it would function as an SG. YMMV.

soccer4m, you have any thoughts as you have an XJ.

[Restless]

Thank you for the quick responses.