Preferred Head Gasket

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Composite is easy but I suspect they contribute to head warpage because they crush unevenly. I've had them blow out over time. I've had zero failures since going to solid copper with pliobond sealer and .005" fine copper wire around the pushrod tunnels and oil return. Solid copper only needs one or two re-torques. Without the pliobond sealer the copper usually weeps. Other sealers are less reliable.
 
Composite, but for an 850 I cut them narrower, more like a 750 gasket ( white area removed):

Preferred Head Gasket


It makes for a more even and higher specific pressure. Plus better cooling.
Most important is to keep the head torgued up to spec, which is IMO, next to impossible with the std studs below the exhaust ports.
They need to be helicoiled or fixed with an insert.
 
Now that ludwig entered into the conversation, he reminded me of what I have added to the 850 engine. By making 4 custom plugs that fit on top of the Allen bolts but flush with the top deck of the cylinder. These support and help the flame ring where the counter-bores gets real close to the edges of the gasket. I used old valve guides for stock and turned these on my lathe to fit the counter-bores. A trick I learn from you ludwig from a previous posts. Thanks again for the little gem of knowledge.
Cheers.
 
Ludwig, if you cut down the 850 gasket as per your pic, is it necessary to use the 4 x stud bolt plugs to fill the gap back to barrel surface level?
Regards Mike
 
CNN are your plugs dead flush with the barrel or set a few thou' below the barrel surface
Regards Mike
 
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flatness counts for any good sealing , the cylinders usually are good and flat but the heads....?
 
If your head gasket is crushing then its crushing unevenly. Ask yourself if that will contribute to head warpage. How many times do you want to skim your head?

I've never had to mill my head. Only a light rubbing off the high spots. See this vid at 3:33

There's no point in getting it perfect if its just going to warp again.
 
Yes thanks again. As the picture that ludwig posted I think used aluminum plugs. He has to keep his bike light... don't you know. ;)I just used old 850 cast iron valve guides that I pulled out of my head when I replaced them with kibblewhite type. A hole in the center is needed to pull them out if you need to get at the cap screws again with a hook tool or a small tap if these are tight. I made mine flush.
 
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