Are my GT380 head gaskets too large?

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sportston
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Are my GT380 head gaskets too large?

Post by sportston »

Would anyone be able to tell me if my gt380 head gaskets are too big please? I am rebuilding the engine and went to fit the DK head gaskets and they look like the fire ring is too large. There is a gap between the edge of the bore and the gasket of approximately 2.5mm all around. Is this right?
I am concerned that a gap this large would reduce the compression ratio significantly.
Any help would be much appreciated.
Thanks
Tom
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Jimroid
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Re: Are my GT380 head gaskets too large?

Post by Jimroid »

I would not use those. Not sure how the oem gaskets fit, but I would be shocked if they have that much clearance.
sportston
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Re: Are my GT380 head gaskets too large?

Post by sportston »

hmm. That's what i was wondering. I mean these would be about the right size if I was 5mm overbore right? I'm no 2 stroke expert. I've rebuilt a few strokers, but have no recollection of the gaskets being like this. They are D & K gaskets in case anyone was wondering.
Vintageman
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Re: Are my GT380 head gaskets too large?

Post by Vintageman »

It would work, maybe, but you will never have peace of mind if you run it like that... That's what happens to me if I see a bit of an issue. Feels so good when everything is correct. Go OEM!
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sportston
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Re: Are my GT380 head gaskets too large?

Post by sportston »

Yes. Thanks for the advice guys. I was wondering....are the copper gaskets any good? or more likely to leak?
Craig380
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Re: Are my GT380 head gaskets too large?

Post by Craig380 »

I've used both genuine Suzi gaskets (when I could get them) and pattern gaskets on my old 380, and when the gaskets are brand new and unused they have ALL had 2-3mm clearance from the bore to the gasket.

Don't forget the flame ring squashes somewhat when the head is torqued down, which reduces the clearance. Also, the gasket has to accommodate oversize pistons, and there are no oversize gaskets.
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sportston
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Re: Are my GT380 head gaskets too large?

Post by sportston »

Craig380 wrote:I've used both genuine Suzi gaskets (when I could get them) and pattern gaskets on my old 380, and when the gaskets are brand new and unused they have ALL had 2-3mm clearance from the bore to the gasket.
Very interesting to note. Thank you for the extra info. I am kinda wondering whether to fit the pattern gaskets now. If they don't work well I guess it is not too hard to remove the head and replace them
Warehouse1001

Re: Are my GT380 head gaskets too large?

Post by Warehouse1001 »

My factory stock Suzuki GT750 head gasket was also somewhat "oversize" if you will. Pretty typical in my experience. Chuck
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tz375
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Re: Are my GT380 head gaskets too large?

Post by tz375 »

A large gap like that not only wastes power and fuel but is also prone to detonation.

Try to get gaskets that are less than 1mm larger than the bore.
sportston
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Re: Are my GT380 head gaskets too large?

Post by sportston »

that makes sense, but right now I am broke. Getting married in May, so must save pennies for wedding. But after that, I can afford to spend a little on the bike. I assembled it with the crappy gaskets today. But I have plans to put thinner copper ones on in the future.
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