KZ900: Cylinder Head Gasket: 1 or 2 Piece???

Hey all,

Question, which is better, the 1 or 2 piece head gasket?

Reason I ask is I ordered a complete gasket set from Z1 and it contains the 2 piece head gasket. When I received my Weisco piston kit, they also sent a head gasket but in a one piece design...

As can be reviewed in the attached image, OEM calls for a two piece gasket so safe to assume, stick with OEM...

Thoughts, comments or experience otherwise?

Thanks,

OMR

hey omr, i've used both on lots of different egines i've built over the years it doesn't really matter which you use the only thing you have to do different on the one piece gasket is to fill in center o-ring tunnel i've seen epoxy used but i always use high heat silicon not that r.t.v crap the high heat stuff always holds better against the hot oil flowing around it. i've never used the epoxy method in always seem a more permanant method. i've had about the same luck with each so pick-em. i personally don't build alot of small inch motors anymore so i'm stuck using one piece copper gaskets on these big motors the last one i built for my self was a 1075 i used the one piece cometic gasket that comes in the wiesco kit i built that motor 8 years ago ive got around 20,000 miles on it and i have never had a problem with it. hope this helps.

timebomb33 wrote:

hey omr, i've used both on lots of different egines i've built over the years it doesn't really matter which you use the only thing you have to do different on the one piece gasket is to fill in center o-ring tunnel i've seen epoxy used but i always use high heat silicon not that r.t.v crap the high heat stuff always holds better against the hot oil flowing around it. i've never used the epoxy method in always seem a more permanant method. i've had about the same luck with each so pick-em. i personally don't build alot of small inch motors anymore so i'm stuck using one piece copper gaskets on these big motors the last one i built for my self was a 1075 i used the one piece cometic gasket that comes in the wiesco kit i built that motor 8 years ago ive got around 20,000 miles on it and i have never had a problem with it. hope this helps.

what he said!

only thing you have to do different on the one piece gasket is to fill in center o-ring tunnel

Since there isn't any true difference, I'm with you where I don't like the epoxy idea and RTV seems a little messy and if not done accurately, I could develop an oil leak.

2 Piece it is, thanks guys...

OMR

Hi All; Back in the day, I tried to use a copper gasket and the thing leaked like a sieve. Obviously, I didn't know what I was doing. Soooo, what's the deal? The cylinder studs can only put so much PSI on the gasket and copper compresses pretty well if it's annealed (like brake banjo fittings). So what do you do, deck the block and leave the liners a couple of thousands high? Do you cut O ring grooves in the liner lip to make the seal? I just don't get it, it seems like there is way too much surface area for the available clamping pressure. Get me up to speed on this one and ride safe, Steve

We've been filling the oring groove with epoxy since the 70's and never a problem.

I've had copper base and head gaskets in my 1075 MKll for years and it seeps just the tiniest tiniest bit at the head gasket, using APE studs and nuts, 1211 3 Bond and Gaskacinch. YMMV.

Yup.I remember a few years ago,using the one-piece gasket AND,also using the center o-ring.
The bike ran great til it warmed up.
This was the result,when I pulled the head.
(lesson well learned).
And as far as the silicone you see in the pic,it was only a skin,to help keep the o-ring in place.No thickness at all.
Look closely at the pic,and you can clearly see where the head was leaking.

Exactly what I was thinking would be an issue in using the one piece Sandy....

That's why I couldn't understand how that was going to work out ideally without leaks. The picture you provided was how I imagined but wasn't sure, screwed with my mind it did...

Definitely 2 piece it is....

Thanks all, cleared my old head... :S

OMR

Sandy, can't use the o-ring and a one piece- the groove must be filled to use a one piece head gasket and the o-ring gets tosssed.

NB. Just thought of this : If you run copper head gaskets on the street the cylinder sleeves MUST be o-ring grooved at a machine shop and stainless wire of the appropriate diameter inserted into the grooves. If you don't it will leak like Jed Clampett's hole in the ground.

I believe the one piece is thinner and is a very good gasket. Just fill in the groove with silicone and you wont have any problems.

Jack wrote:

Sandy, can't use the o-ring and a one piece- the groove must be filled to use a one piece head gasket and the o-ring gets tosssed.

NB. Just thought of this : If you run copper head gaskets on the street the cylinder sleeves MUST be o-ring grooved at a machine shop and stainless wire of the appropriate diameter inserted into the grooves. If you don't it will leak like Jed Clampett's hole in the ground.

so i just bought a two piece copper gasket and installed it without this. so i guess i'll be taking it off soon? why use a copper gasket then? does the wire need to be replaced each time the head comes off?

Jack wrote:

Sandy, can't use the o-ring and a one piece- the groove must be filled to use a one piece head gasket and the o-ring gets tosssed.

That post was my whole point,Jack,thanks.
I learned the hard way,but it only cost me a new head gasket and some more time.
If you look at the date on that posted pic,you'll see that it was a few years ago.

Someone here told me(back then) that it WAS ok to use the o-ring WITH a one-piece head gasket.
Sometimes the best experience is doing it wrong the first time.