Topic: Squish/Quench?

[HondaMan]

let's see...

cb750K0 claimed BHP: 67
'79cb650 claimed BHP: 63
           
throw in a 5mm overbore, 10.5 compression ratio, mike reick porting, 29mm carbs, and a lightened and balanced crank? i'll double mike's bet! 

Watch out for the parts I just sent Terry...   

[Terry in Australia]

let's see...

cb750K0 claimed BHP: 67
'79cb650 claimed BHP: 63
           
throw in a 5mm overbore, 10.5 compression ratio, mike reick porting, 29mm carbs, and a lightened and balanced crank? i'll double mike's bet! 

Sorry mate, I should apologize, I wasn't wearing my glasses and didn't read that right, I thought you said you were gonna smoke my STROKER.

I thought you were talking about the other engine I'm collecting parts for, I've got another F2 bottom end and some 73mm pistons, I'm just looking for a good CB900F crank so I can stroke it out to 1170. When I "thought" that I read that you were gonna "smoke" me with a warmed over CB650/712, I fell about laughing!

Sorry about that, I better stop drinking when I'm on this site. The only "stocker" that I've got is my K0, but I don't think I'd be interested in racing with it. Cheers, Terry.    

[FunJimmy]

The reason I thought shaving the head makes sense is that there is a slightly chamfered ring around the combustion chamber. Decking the head would flatten this out and provide a larger squish area.

Comments?

Jimmy

[Jerry Rxman Griffin aka MuthaF'er]

Better watch out. I think Terry is STROKING his smoker 

[Terry in Australia]

Better watch out. I think Terry is STROKING his smoker 

Or maybe I'm smoking my stroker!

[HondaMan]

The reason I thought shaving the head makes sense is that there is a slightly chamfered ring around the combustion chamber. Decking the head would flatten this out and provide a larger squish area.

Comments?

Jimmy

Removing the chamfer on the 750K head converts it from a swirl-stratified mix engine to a conventional quench-squish design (while raising compression a bit). The original design uses the induced-charge spin (formed by those "pockets" around the valve faces) and edge accelleration to create a leaner-center-than-outside-charge. This swirling action provides more torque at low end and lower emissions at high RPM, while improving cooling through the whole range. I think I have a more detailed post about this, somewhere (maybe in the FAQs somewhere?).

Removing it provides more HP, though...    Adding hemi head (another post around here) also reduces the swirl, but adds a rich spot in the 1/4 to 1/3 throttle range. Milling the head .010" helped, but I think it needs another .008"-.010" to finish the conversion to a squench design. We'll find out, next time I tear it down.... 

[FunJimmy]

Thanks Honda Man

The final question. Should I shave the head and create a conventional quench design or leave it as designed?

Cheers
Jimmy