modifying a honda head gasket for overbores

seanmx57 · Post by **seanmx57** » April 1st, 2009, 10:43 am

Has anyone got any experience enlarging the OEM gasket to 91mm. I'm not sure how to go about it other than to order a cometic. I've been told cometic has larger ones. I own the OEM that came in the motor kit.

I have a once used one that EG modded 4 me. I'm sure lewisclan will tell me to reuse it w/ a bit of paint and some chewing gum, no offense J.

~Trever · Post by **~Trever** » April 1st, 2009, 10:52 am

Is it a steel gasket?

seanmx57 · Post by **seanmx57** » April 1st, 2009, 11:04 am

I think OEM are steel, they are metal 4 sure

lewisclan · Post by **lewisclan** » April 1st, 2009, 11:07 am

yep copper coat spray & throw it on

pstoffers · Post by **pstoffers** » April 1st, 2009, 11:45 am

lewisclan wrote:yep copper coat spray & throw it on

X2 LET HER BUCK!!!

~Trever · Post by **~Trever** » April 1st, 2009, 9:33 pm

There is a place in san dimas that does it if you are in socal but any machinist should be able to do it. I have done it myself with a hone but it ruins the stones.

iggys-amsoil · Post by **iggys-amsoil** » April 1st, 2009, 11:07 pm

3" drum sander?

seanmx57 · Post by **seanmx57** » April 2nd, 2009, 4:22 am

iggys-amsoil wrote:3" drum sander?

That might work, I have a 2.5"

Does anyone know why the holes in the gasket are way smaller than the jacket orifices? Seems like honda is limiting the flow, but why?

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » April 2nd, 2009, 5:16 am

the water holes choke the path of least resistance so that the entire cylinder has the same amount of heat transfer. The old jugs with the rear inlet had the front 2 holes open the entire waterjacket size, and maybee 3/16 size holes thru the other waterjacket openings.

yota · Post by **yota** » April 3rd, 2009, 10:33 am

seanmx57 wrote:Has anyone got any experience enlarging the OEM gasket to 91mm. I'm not sure how to go about it other than to order a cometic. I've been told cometic has larger ones. I own the OEM that came in the motor kit.

I have a once used one that EG modded 4 me. I'm sure lewisclan will tell me to reuse it w/ a bit of paint and some chewing gum, no offense J.

unless you are cutting the head back also what would the gasket hurt?

seanmx57 · Post by **seanmx57** » April 3rd, 2009, 10:38 am

The head is modded for the overbore.

BannedCR500Riders.com

modifying a honda head gasket for overbores

modifying a honda head gasket for overbores

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