need help with cb 750 k rebuild

[rough rider]

hi guys , long story but to cut it short i am building a cb 750 k DOHC engine up from 2 motors due to a hole in a crankcase
have completed the bottem end and are now fitting the cylinder from the crank case with the hole to another crankcase
now when fitting the cylinder there are 4 orings that fit on the 4 inner rear studs . not sure what they do as they just slip over the stud ,stud is surrounded by gasket then cylinder is fitted  but the stud shaft is then outside of the cylinder
both motors have different style head studs , one has an exposed spiral on the out side other studs are normal studs
now these orings , on the motor with the hole in the case , this had 2 green orings on each of the 4 center studs one on top of the other ( total of 8 orings ) , the crankcase i am using had 1 black oring on each stud ( total of 4 orings )
the gasket set i got was an after market one and for some reason has 16 of the green orings stated before and i cant see where they would be used anywhere else , but the gasket set does fit a few different models 
gasket set also has 4 black orings which look similar to the ones removed
going by parts books i have found on the internet and the clymer manual i have , it looks like the black orings are the ones to be fitted but dont know why this other motor has the green ones fitted
does anyone know what are the correct ones to be fitted and what these orings actally do ??
dont want it to leak oil and have to tear it down again
thanks in advance for any help
 

[Ktm181]

sounds like the o rings would stop oil travelling UP THE STUDS and then to the outside, Kawasaki have a similar system from memory. YOU would need to either get a manual or talk to an old school jap mechanic.....Mick Dyer in Penrith NSW, Puds Four parts in Victoria.....Rex Wolfendon  at TRex engineering in Melbourne also, these guys currently work on those old girls regularly (me too!) and they might remember and explain better on the Honda Four. PM me if you cant find out, i have a mate who is doing his and he might also remember, he's been riding his and dragging it almost daily sinc 1977.

good luc with it,
Kt.

[matcho mick]

f series??,be a trick k DOHC ,16 green ones would go under the valve guides,no way honda,or mechanic would doubleup 2 o rings fitted in your 1st motor , 4 o rings at the back from memory on 900's ,don't remember why ,ktm 181 might be right,seal studs,but geezas that was 30 fugging something years ago  ,exposed spiral studs were a pain,filled up with road gravel,made taking the block off a task,used to upend the motor so the shit didn't go into the motor,

[Doc]

1979 CB750KZ  were dohc without the Bol'Dor styling. Tim would be the man to ask 

[rough rider]

thanks KTM181 , I rang puds four parts today and altho he hasn't worked on many DOHC motors he said the green smaller oring doubled up  don't sound correct , and his workshop manual like mine only shows 1 o'ring on each stud .
thanks to matcho mick I did some more looking around on the internet and found the 16 green orings 10x 1.5mm , which as you said appear to be valve guide sealing oring's , not getting confused with valve stem seals , but these aren't shown clearly in any workshop manuals I can find,  only listed as a part
so I think I have it sorted out now , and someone must have put the original motor together incorrectly
btw this is an 1981 CB 750 K DOHC ex police bike
 

[Tim754]

Dual overhead camshaft CB750KZ and 900s,  Single row is all I have ever used no double ups ever.

 Come to think of it, never used doubles on any Single overhead camshaft  K and F series either, and put a few of them together that sometimes work... Tim754

[matcho mick]

ha,i used to work on police bikes,kawas,beemers,& the 750 hondas,(god knows why they went to them hondas after the other 2 "larger "models),triumphs were gone by then,got chased by a few when i was younger ha ha ,probably why "fugging " pops up??