cool head

[hyperman]

what size domes are some of you guys running,and what kind of compresion numbers are you getting, just being curious,currently i am running a 18cc and seem to be maintaining 180psi .

[86 Quad R]

i think you should be running a higher compression with a 18cc dome. i was getting 180/185 with the stock cc chamber (21/23) and a shim gasket.

[trailwart]

my buddy was at 195 on a 19cc

[hyperman]

yea i agree with you,im not sure what the deal is, i put the 20cc in right after my last bore and she was way low 165 psi so i put the 18cc in,and its held 180 all summer long so i guess i wont worry to much about it at this point,i am getting good plug readings to.

[86250rrider]

are you running a head gasket by chance?or the o-rings?

[hyperman]

im running a cometic head gasket,the only o ring is in the dome.

[86250rrider]

thats what i thought...that gasket is as thick as an old buick! if you switch to a split trx or a cr250 your compression will go up about 25-30 compared to the cometic gasket. your fine then ,just switch when you want to get another 5 horses.:D

[86 Quad R]

heck yea!!!! those cometic gaskets are something like .050" lol

[86250rrider]

lol....if you used a cometic gasket and the 22cc dome i might not even start wirth a fresh motor!:D



good sealer and a split trx for me!!

[hyperman]

okay guys,i got what i believe to be a cr gasket part #12254-ks7-881 now i know this is gonna sound stupid,but which part of the 3 piece gasket should i use,anybody have step by step directions,and your right the cometic is a thick gasket but that is what colby sold me so that is what i used. thanks for all the help figuring this out

[86250rrider]

first off....the cr is only one piece.if you have a 3 piece,carefully drill out the two rivets.then use one of the outer pieces.make sure you clean the head and jug well for residue.use a good sealer like teflon..i use three bond 1211 on both sides of gasket.install on bike with rounded tit facing forward(make sure the bigger slot is by the exhaust port) and square tit facing back.torque to 20-25 ft. lbs in 3 stages and LET SIT OVERNIGHTbefore adding coolant . i reuse these gaskets over and over with this method. ROCK ON !!!!!:macho

[hyperman]

all right thanks again 86 250rider,ill give it a try and see what happens,ill get back to yea in a couple of days

[86250rrider]

oh do a compression check after its all together. 185-up needs some mix with race fuel. VERY IMPORTANT !!!!!!:macho

[hyperman]

okay i went with the split gasket and a 16cc dome checked compresion 235psi thats to much for me ,gonna beat the bottom end out of her, i think tomorrow ill pop the 20cc in with the split gasket and see what that does i would like to see it right around 195 200 psi.

[Showcase]

i have a 20cc in with arond 180 compression.

[ERBE]

even at 180 I would run race fuel 110 2gal mixed 3gal 91/93 to get around 96 oct, keeps you from pinging/denatation specialy when your in the upper revs, hell I run race fuel in my kids blaster same ratio, standard gas sucks even at 91 oct, so your looking at 5gal to mix with 7 to 8gals of 91oct and your motor runs even cooler