98mm CP Head Gasket O-Ring

Engine, intake, exhaust, EFI, chain, sprockets, etc.
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cdsracer
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Joined: Wed Mar 10, 2021 10:41 pm

#1 Post by cdsracer »

My wife's 460 is slowly pushing coolant out of the reservoir while running. This started happening two rides after it hydrolocked (stood it on the grab handle to fit it in the trailer and it was in there for several weeks). It was barely hydrolocked when I got it out of the trailer...more like hydrochallenged. When I hit the starter it struggled through the compression stroke and pushed some oil out of the exhaust, freed up and started, smoked for a bit then ran fine.

I pulled it apart this morning and as I suspected, the o-ring on top of the cylinder was squishing out and leaking very slightly. The o-ring doesn't look too healthy anymore and after inspecting the head, I see that where the o-ring mates with the head, there is a groove developing in the head itself where the o-ring is rubbing on the head. This makes me want to machine the head before reassembly.

Anyone have any experience with this?

The stock ASSO piston kit o-ring is too fat to sit in the CP 98mm groove. So I am in need of a replacement. Know where I can get one?

Thanks.
-Chris

kdeal
Posts: 4
Joined: Wed Mar 10, 2021 10:41 pm

#2 Post by kdeal »

Chris get a hold of Brad, he has some.

wistech
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Joined: Wed Mar 10, 2021 10:41 pm

#3 Post by wistech »

If high compresion, be sure to clay the head before resurfacing. I've gone as much as .011" on stock pistons to bump up compresion. Most of the time you only need to take .005" or less to get rid of cylinder wear rings. Check your sleeve protrusion as well. Lots of the aftermarket sleeves can be all over the place for deck height. If the sleeve isn't tall enough it will let gasses eat the oring up and rock around too much.

cdsracer
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Joined: Wed Mar 10, 2021 10:41 pm

#4 Post by cdsracer »

Thanks guys...got parts today, should be running again for the weekend.

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