Honda CBR XX Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #1
Im looking to do a set of drop in cams aswell as a thinner head gasket to bump my cr up a bit. Any clue how thick the stock headgasket is or how thin i can go before cuasing valve to piston clearance problems?
 

·
Registered
Joined
·
1,570 Posts
Stock head gasket is .032" iirc.
The clearance you want to go by is piston to head which sets the "squish".
I would suggest .040" minimum.
When setting valve to piston, I'd suggest a minimum of .050" on the intake and .075" on the exhaust.
Check for minimum clearance from about .015" to .005" BTDC on the exhaust valves and .015" to .005" ATDC on the intake valves.
To raise the CR, either change the pistons or mill the head.
.040" mill should raise CR approx 1 point.
 

·
Registered
Joined
·
458 Posts
To raise the CR, either change the pistons or mill the head.
.040" mill should raise CR approx 1 point.
Inquisitive question here - those Carillo forget pistons require thinner gasket, right?

Also, raising CR 1 point, so 12:1, would this raise power in any significant way?
 

·
Registered
Joined
·
1,570 Posts
Not sure what you are referring to...Carillo makes rods.
1 point increase might give 1.5% HP increase....in my opinion, not worth splitting the cases for.
It would be advisable if you had a number of engine mods that you wanted to do at 1 time, for example:
cams, port the head, overbore with higher CR, rods...etc.
 
1 - 6 of 6 Posts
Top