SuzukiSavage.com - Imperfect mating surface.

Moarpower Senior Member Offline SuzukiSavage.com Rocks! Posts: 331	Imperfect mating surface. 11/28/22 at 18:02:43 Hi guys. Noticed some small marks on the head-gasket mating surface. Still usable? If not I'm not spending any more money on this bike. I might just use a dab of hondabond and see how it goes.
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DragBikeMike Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 4194 Honolulu	Re: Imperfect mating surface. Reply #1 - 11/28/22 at 18:58:52 Please refresh my memory. Are you installing a 94mm piston? IMO, as long as you are using a stock multi-layer steel (MLS) head gasket, those blemishes should not present a problem. The critical sealing area is around the liner. The embossed fire ring in the MLS gasket should be situated right on the cast iron liner.
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Moarpower

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Re: Imperfect mating surface.
Reply #2 - 11/28/22 at 19:15:38

DragBikeMike wrote on 11/28/22 at 18:58:52:

Please refresh my memory. Are you installing a 94mm piston?

IMO, as long as you are using a stock multi-layer steel (MLS) head gasket, those blemishes should not present a problem. The critical sealing area is around the liner. The embossed fire ring in the MLS gasket should be situated right on the cast iron liner.

Thanks Mike.
I'm using a 96.5mm piston on this.
I have ordered the multilayer gasket.

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DragBikeMike

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Re: Imperfect mating surface.
Reply #3 - 11/29/22 at 08:51:13

Ah yes, the Wossner piston. Be careful with the head gasket. Are you using a stock MLS head gasket. If so, it is designed for a 94mm bore. It will accommodate slightly larger bores, but I'm not sure about the 96.5mm. I know I personally wouldn't use it on a 97mm because it overhangs into the bore.

When a thin head gasket sticks out into the bore it can cause problems with interference and also pre-ignition. Interference in that the piston could hit the gasket, preignition due to the thin steel gasket getting red hot and acting like a glow plug.

But what's good for the goose isn't always good for the gander. I suspect a little overhang might be OK as long as the deck height is negative. As I recall, your compression height was very close to the Wiseco Pop-Top, and that runs well below the deck.

Good luck.

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Moarpower

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Re: Imperfect mating surface.
Reply #4 - 11/29/22 at 17:03:50

DragBikeMike wrote on 11/29/22 at 08:51:13:

Ah yes, the Wossner piston. Be careful with the head gasket. Are you using a stock MLS head gasket. If so, it is designed for a 94mm bore. It will accommodate slightly larger bores, but I'm not sure about the 96.5mm. I know I personally wouldn't use it on a 97mm because it overhangs into the bore.

When a thin head gasket sticks out into the bore it can cause problems with interference and also pre-ignition. Interference in that the piston could hit the gasket, preignition due to the thin steel gasket getting red hot and acting like a glow plug.

But what's good for the goose isn't always good for the gander. I suspect a little overhang might be OK as long as the deck height is negative. As I recall, your compression height was very close to the Wiseco Pop-Top, and that runs well below the deck.

Good luck.

Thanks again Mike. I hadn't considered that issue. Silly oversight on my part

Is there another option for a head-gasket I should consider ? I will likely use some copper spray on this application also.

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Gary_in_NJ Serious Thumper Offline LS650 Cafe Racer Posts: 2626 Amongst the Twisty Roads	Re: Imperfect mating surface. Reply #5 - 11/30/22 at 04:38:29 Moarpower wrote on 11/29/22 at 17:03:50: Is there another option for a head-gasket I should consider ? I will likely use some copper spray on this application also. In my experience, head gaskets should go on dry.
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Re: Imperfect mating surface.
Reply #6 - 11/30/22 at 11:20:57

I agree, the stock MLS gasket should be installed dry. It has a thin elastomer coating. That copper spray will probably screw up the coating. They work great just as they come from the factory.

If you opt for a copper gasket, you will need perfectly flat sealing surfaces. The .002" flatness spec given in the tech manual won't cut it with the copper gasket. The head and cylinder surfaces must be perfectly flat. The copper gasket gets installed with a coat of the copper spray or a uniform coat of silicone sealant (uniform coat very hard to achieve). Copper Gaskets Unlimited has the CAD drawings on file. You provide the make and model of the engine, and specify the thickness and bore size. The stock gasket is .028" thick so you want a gasket close to that thickness. As I recall, they offer .026" which works good. You can email Lani Visconti to order gaskets. His email is coppergasketsunlimited@yahoo.com.

BTW, the copper gaskets are a bit more trouble to install, but you can reuse them. Since the stock gasket is close to $50 bucks a copy, the copper gasket does have certain advantages. It's cheaper and eliminates the overhang issue. I suspect that there are vendors in Australia/NZ that make copper gaskets. CGU is in Phoenix Arizona.

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Moarpower Senior Member Offline SuzukiSavage.com Rocks! Posts: 331	Re: Imperfect mating surface. Reply #7 - 11/30/22 at 15:06:03 Thanks guys. Yes I was thinking I'd need to use a copper gasket with spray due to the oversize. What would be my best bet here? Should I just try the MLS gasket and see if it works fine ? Would those small marks make a copper gasket not usable?
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Moarpower Senior Member Offline SuzukiSavage.com Rocks! Posts: 331	Re: Imperfect mating surface. Reply #8 - 11/30/22 at 18:01:40 I have contacted many local gasket manufacturers with no luck. These bikes just aren't that popular here, unfortunately. One however did say they can modify the OEM gasket to suit so I will be going that route
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Ruttly Serious Thumper Offline Thumpers Rule Posts: 4997 Manteca , CA Gender:	Re: Imperfect mating surface. Reply #9 - 12/01/22 at 18:04:01 Most big bore piston manufacturers have or have a go to head gasket supplier. Try calling around.
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Moarpower Senior Member Offline SuzukiSavage.com Rocks! Posts: 331	Re: Imperfect mating surface. Reply #10 - 12/01/22 at 22:24:27 Ruttly wrote on 12/01/22 at 18:04:01: Most big bore piston manufacturers have or have a go to head gasket supplier. Try calling around. Yeah, I contacted all the people I could. I can get a solid gasket made, but I don't think that will work for me with this head if it needs to be as flat as Mike has suggested.
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