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XL600R head gasket thickness question

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I'm rebuilding an 86 XL600R - the previous owner put a wiseco "11:1" piston in it, 1mm over (4332M10100). I need a new head gasket, but from reading here it sounds like it will be difficult getting the bike to run as a woods bike, without pinging, on 91 octane. I'm thinking about making a slightly thicker copper gasket, or just trying to run it with a wiseco gasket, can't decide. The used head gasket I pulled off the bike measures between 0.040in to 0.048in in the crushed area.

Do you think I can get away with a wiseco gasket and tune it to run on 91 octane with that piston? I plan for this to be a woods bike, so it's going to be running slow and hot probably. Or should I make a thicker gasket? If so, how thick should I make it to drop the compression a bit without radically affecting timing?

Thanks!

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How much slack is in your timing chain?  That might be a limiting factor to raising the cylinder head.

It might be easier to make a thicker cylinder base gasket.

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Not sure how much slack is in the chain since it was... let's say "damaged", when I got it. A thicker base or cylinder head gasket will have the same effect on timing (I think), although the base gasket isn't under much pressure. 

I did some further research - the stock compressed gasket thickness is 0.040in. The wiseco "11:1" piston is 0.015in higher according to headtrauma's chart. So maybe I add 0.005in? Or just say screw it and use a regular gasket? Cometic said they can make a custom gasket of just about any thickness if I don't want to make it.

If anyone has the combustion chamber volume and piston deck height for the xl600r I can run the numbers for real and figure this out.

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54 minutes ago, Cam_alexander said:

Well..... My head is about .75 inches in diameter but idk what all this motorcycle talk is

My condolences.   :lol:

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