K series vs. late F series

[Piute]

                                                  Piute Putt

The F2/F3 not only has intake valves that are 2mm bigger in diameter than the rest of the CB 750 models, they also have a bigger (approx. 5cc) larger combustion chamber. That means that, with a given piston kit, you get less compression than advertised in a F2/F3 engine. Some manufacturers (Wiseco) listed different kits for K and F models. Dynoman has 836cc kits especially for the F2 head. The F1 head has (almost) the same C/R like the K models.
                                        Just a Lil " Mo in FO "........Piute N Judose........


 FROM DYNOMAN AD:
                  As the 77-78 Honda 750 F2 has an 18% larger combustion chamber
                  to compensate for the larger valves, through the years many
                  people have installed the standard 836cc (ex: Wiseco K836)
                  kits for the 69-76 engines only to discover that the
                  compression was too low to give them the extra power that they
                  were after.
                  Dynoman offers our custom 836cc piston kit for the F2. It has
                  the correct dome to raise the compression to a true 10.5:1.
                  These pistons are state of the art diamond cut on CNC machines
                  in the USA from 2618 aluminum forgings. This is the same alloy
                  used in many prostock pistons. This process makes them lighter
                  than some of the cast pistons used in the 70s, but much
                  stronger. They also come with a brushed dome to smooth any
                  sharp edges.
                  The piston features large valve pockets for the 31 and 34mm
                  valves used in the F2 engines. They also have
                  contact reduction grooves above the top ring for pre-ignition
                  control, and accumulator grooves below the top ring for better
                  ring control.
                  They are the same bore size as the standard Wiseco K836cc kit,
                  so they are a drop in for any F2 with the standard K836 Wiseco
                  kit already installed.
                  Made in the U.S.A....reposted by Piute



         Kits for F's  http://www.dynoman.net/engine/pistons/custom.html#F2
  others just have to look harder

[Piute]

   Sorry maybe
 Maybe my link gave you to much info
was copied wrd 4 wrd for eng. mod.
 BUT, from it you can see ; A straight swap is not possible with out making larger valve holes,witch is very critical of these machines...,that would be using "F" parts in "K" head as you were asking ?
 
  This brings me to A  ? (wake up ShinyRibs 1st part Chevy)on A 350sml block you can put so 327 heads on it and bring up the compression ratio,people do that all the time(ole Indian trick)
  So would that work putting complete head from A "K" on A "F" ,Smaller combustion chamber ??
   

  Sorry Dav. but good points here;  Cause IF it ("K" heads on "F")brings up compression then would drop compression if "F" heads on "K" RIGHT ,were talking no mods just bolt on ??????????
 

[Re-run]

Strange, my post from this morning seems to have disappeared.
Anyways, so far, you can use heads from 70-76 on any year engine in that range for the K bike and K heads.
You cannot swap early K heads for later K heads and vice versa. There are additional oil lines in the later heads. I will check more on the F but I think the f/f1 can be used on the 77/78 K but not earlier K bikes.

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I think, you are confusing Piute's post here with Dave Esch's post about swapping heads.
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