TOPIC: Top-End Redo

Don't see why you couldn't use the OEM gasket.

I've used a slightly smaller gasket with no ill effects. In fact I'm reusing a one piece Z1900 gasket now with no problems. The one I just ordered is 72mm and is the same as the last one. I replaced it when I installed my new APE studs earlier this year.
You shouldn't have a problem with the OEM one.
Steve

baldy110 wrote: Don't see why you couldn't use the OEM gasket.

Is it possible Cometic packaged the wrong size head gasket by mistake?

Considering the previous advice from Dave A. (Street Fighter LTD) was so well defined, I am now just a little uncertain about this.



Please view my reply post to Street Fighter LTD on page 3

daveo wrote:

baldy110 wrote: Don't see why you couldn't use the OEM gasket.

Is it possible Cometic packaged the wrong size head gasket by mistake?

Considering the previous advice from Dave A. (Street Fighter LTD) was so well defined, I am now just a little uncertain about this.



Please view my reply post to Street Fighter LTD on page 3

I will always defer to MTC / Joe Hopper / and Cometic
I just try and raise points to be considered .
As a lot of us have many years experience with kaws and hi performance motors you learn never to assume anything during a build
Check everything for proper fit and function . If you dont you may lose a race or a nice expensive street build and my pockets
are not as deep as they used to be .
Just verify with MTC or Joe H that you have the part that matches your application
Dave

Street Fighter LTD wrote:

daveo wrote:

baldy110 wrote: Don't see why you couldn't use the OEM gasket.

Is it possible Cometic packaged the wrong size head gasket by mistake?

Considering the previous advice from Dave A. (Street Fighter LTD) was so well defined, I am now just a little uncertain about this.



Please view my reply post to Street Fighter LTD on page 3

I will always defer to MTC / Joe Hopper / and Cometic
I just try and raise points to be considered .
As a lot of us have many years experience with kaws and hi performance motors you learn never to assume anything during a build
Check everything for proper fit and function . If you dont you may lose a race or a nice expensive street build and my pockets
are not as deep as they used to be .
Just verify with MTC or Joe H that you have the part that matches your application
Dave

Thanks Dave, I will definitely check into it.

Unless there is an actual 74mm. two-piece fiber alternative available, I will likely end up using the Genuine Kawasaki head gasket, considering the following information.

Besides having the slightly smaller cylinder opening, the Cometic gasket thickness is .15 to .20mm. thinner than the Kawasaki gasket. That is close to the .005" milled from the head in 2015, so there would be a further increase in compression with the Cometic, which would also bring the valves that much closer again to the pistons.

I have a gpz1100b2 fitted with bathtub head and cams and have the MTC unitrack kit with 17mm wrist pins.Used cometic gaskets supplied without anything taken off piston crowns.I use Dyna 2000 for ignition and have RS34 carbs and bike runs great. have a large oil cooler and use 99 octane fuel here in the UK.

zippy61 wrote: I have a gpz1100b2 fitted with bathtub head and cams and have the MTC unitrack kit with 17mm wrist pins.Used cometic gaskets supplied without anything taken off piston crowns.I use Dyna 2000 for ignition and have RS34 carbs and bike runs great. have a large oil cooler and use 99 octane fuel here in the UK.

Please post a pic of a piston, and a couple or few of your bike?

Don't have piston pictures as the engine is built.it's the 1135 10.5 -1 compression kit for the unitrack motor.Maybe Joe recommended taking a bit off the crown because you skimmed the head.I'll post a couple pictures of the bike for you in a couple of days, need to use my wife's phone as mine is from the stone age.

MTC G1135-3 Piston as provided:

Head Gasket Comparison. Cometic and Genuine Kawasaki

Cometic Technical Service today put a halt to using either one of these gaskets. Said to "definitely use set having 74mm + bore opening for certain, and this set must have been improperly stamped when manufactured."

So, thank you again Dave for pointing this out. I prefer to err on the side of caution.

daveo wrote: Cometic Technical Service today put a halt to using either one of these gaskets. Said to "definitely use set having 74mm + bore opening for certain, and this set must have been improperly stamped when manufactured."

So, thank you again Dave for pointing this out. I prefer to err on the side of caution.

I Hate being right to slow you down , Love it to keep your project bulletproof
Keep up the good work
Dave

Are they sending you a new one?
Steve

SWest wrote: Are they sending you a new one?
Steve

Cometic said my supplier needs to take care of it, and resisted assisting any further on the matter.
So I sent another email to Joe...



Update 10/08. Beep-beep-beep, ur-ur-ur, screech~~~uh...pop-boom

MTC says STOP!

Think the piston is the same as mine, forgot to say i also have Ape studs and head nuts.

Street Fighter LTD wrote:

daveo wrote: Cometic Technical Service today put a halt to using either one of these gaskets. Said to "definitely use set having 74mm + bore opening for certain, and this set must have been improperly stamped when manufactured."

So, thank you again Dave for pointing this out. I prefer to err on the side of caution.

I Hate being right to slow you down , Love it to keep your project bulletproof
Keep up the good work
Dave

Oh brother...
Boys and girls, we have a problem here. I would rather ignore it and plunge in, but the respect for getting things right has stopped my progress dead cold.

Fortunately my oil sucking engine is still together, and running better than ever!

Just keep a sharp eye on the oil and ride it until snow time
Dave

Street Fighter LTD wrote: Just keep a sharp eye on the oil and ride it until snow time
Dave

I've spent enough time and cash, and am biting at the bit to get this done. Having to wait for re-engineered and manufactured gaskets does not get it for me.
Double-checked the gasket opening relationship to piston diameter. The OEM Kawasaki gaskets easily fit over, but the Cometic don't...except for only one opening of the four. Hmmm.

SWest wrote: Are they sending you a new one?
Steve

Apparently MTC got a bad batch and are returning their stock to Cometic, and will send me one of the correct size.
Anyone planning to assemble an engine with 2-pc. 74mm Cometic head gaskets should double check the bore measurements.

Sure am glad I caught this, and thanks again Dave A.

Clayed one piston to confirm clearances: