82/83 GPZ N1 750 top end kit/tips

So just what bike are we talking about there's three in the Title ?

82 Gpz750 is a KZ750R1.
83 GPz750 is a ZX750A1
82 KZ750N1 is the Spectra 750 shaft drive.
All three use the same family of motor but there are a few difference in them

Sorry about the confusing title. It's a 82 Spectre Shaft Drive N1. Think that's the Gpz motor. I think the rough running and low compression is a bad head gasket. Will be pulling head this weekend and having machine shop check head over for leaks, and a cleaning.

Don't forget the valve guide seals.
Steve

Thanks Steve. Got new seals coming with the gasket set.

I use Viton seals. Worth the extra money.
Steve

Got top end all apart. Head is warped pretty good, center being high, outsides being low. Head gasket was leaking worst in middle, cylinders 2 and 3 which had equally low compression and vacuum. Don't know if I just put a new head gasket back on and see if it resolves my compression and all around poor running engine, and when torquing back down head straightens out enough to be fine. Cam journals with head off were gapped also besides outside journals. Everything checks out fine otherwise. Valves, pistons, rings, cylinder walls. Just concerned about the head being so warped. It's as if someone had it off before and pryed equally too hard and both sides. Any advice on this final issue would be much appreciated. I've learned alot already so thanks. Head is at machinist getting cleaned and new Viton seals put in, and double checked for leaks or bent or burnt valves.

Have you used a straight edge on the block?
Steve

I'll communicate that to the tech when we talk next. I know we can heat the head in the oven or what not and bolt it to a some flat steel to pull it mostly straight, if the block is uneven can that be planed? What would I do? My luck something would have to be out of whack. Getting a real clean bike at a good deal is to good to be true. True the key word haha.

Bending the head back to flat if it's bowed is the prefered method. That will also straighten the cam bores at the same time. Surfacing the head will make the deck flat but the cam bores will still be out though.

That's what we were thinking. Block is pretty flush by the way. Thank you for all of your knowledge and answering questions.

Do you know what other gpz 750 heads would work for my 81 Spectre N1? Thanks in advance.