How much to mill head

I just bought a 94 superjet with pipe,and I want to mill the head. Does anyone know how much to mill head and still run pump gas.Thanks sdbob
 

tor*p*do

Squarenose FTW
Site Supporter
Location
NW NC
have a pro do it
may have to recut squish band, etc
not as simple as taking so and so many 1000ths off

Harry at Group K does it for like $85, I believe
 

keefer

T1
Location
Tennessee
Yep, send it to Group K or ProTec and have them professionally mill and re cut the squish. Use a genuine Yamaha head gasket for the best seal and you will probably get around 175 or 180 psi. Check it with an accurate guage and you should be fine on 93 octane. This will give you noticeably better bottom end snap.
 

Mouthfulloflake

ISJWTA member #2
Location
NW Arkansas
determine the compression ratio you want ( CRx) divide that by the weight of the rider ( RWx), then multiply the resulting number by either .95, or 1.12, whichever one gets you closer to 1.00

when you determine that number, send it to LPW and request that it be milled for pump gas compression.

Or just buy an after market head.
 

Mouthfulloflake

ISJWTA member #2
Location
NW Arkansas
ive been running one that was simply milled as well, it bumped it to 170 or so, no problems on a stock 61x with stock exhaust and stock rev limit.

No idea how much its been milled though, I bought it from some dude on here a couple of years ago.
 

SUPERTUNE

Race Gas Rules
Location
Clearwater Fl.
I used to cut them .055, but you have to recut the squish band if you do. No problems cutting a stock head until the squish band lip disappears. Make sure you use a OEM Yamaha head gasket too! ADA aftermarket heads are better for the long run if upgrading engine packages.
 
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