Head questions

Hello everyone, new to XJ's and the site!! Usually mess with XS's, but found a 1981 XJ 650 for $200 with title so jumped into it to make a bobber for girlfriend.

I have read about YICS etc...found a head off a 82 XJ650, if it turns out to be a YICS head, will it bolt/work with a non-YICS motor? What I have read is NO it wont work... but why/differences....because of extra passages? If so can the passages be capped/blocked off or is bolt patteren etc different?

Any information will be appreciated, thanks!!!

I'll post pics, once uploaded!!

 

here are fresh off the trailer pics, and start of the build....hopefully they come up lol

 

Irishman77,

Welcome. I don't know if a non-yics head would work on a yics engine. Someone will chime in and let you know. If it does...cool. If you'd have to block of the yics passage why the hassle? I'd purchase a '81 head and be done with it. The thing with YICS is you MUST get a good bench sync and set your floats correctly in order for you to be able to block the passage and "running sync" the carbs w/o melting the rubber shut-off seals that go on the yics tool (which you'd need to properly sync the carbs). When your valve shims, bench and floats are set within specs the engine will not heat up as fast or as much and you will be able to allow the tool to cool without melting the seals. It's not that I don't think you can do it...I know you can. Just so you know. Good luck with whatever you decide.

Edit: Just saw the pics. What's wrong with that head?

Gary

 

The head on this one has a broken exhaust bolt...but just didnt break the bolt, took part of fin the bolt goes into...found this other head locally for $10.00 thats why i was asking if i could use this head (if its a yics) on my non yics motor... i could have this head repaired by welding it up etc tapping it but figured if i can use this head why not lol

 

The heads are not interchangeable; while the bolt pattern may be the same, there are a lot of things that won't line up and aren't really conducive to being "blocked off."

 

Irishman77,

And theeeeeere you have it. Thanks BF.

P.S.- Have you checked the compression?
Gary

 

Thanks for the info!! Guess im on a search for a head...or think about fixing this one.

No havent checked compression, since head needs pulling i was going to go on and have jug honed and install new rings all at one time.