Topic: Yet another F2 Top End overhaul... Where do the o-rings/restricters go ?

[flybox1]

If your rings are the RIK brand, both of the top rings have an 'R'  which should face up...

as for the sandpaper on a file  i'd think your causing more trouble for yourself 
manually, its really difficult to keep the surface perfectly flat.  best to get it to a machine shop and get it done right, or at least get it on glass with some lapping paste to really see any low spots.  you could cover the mating surface with some engineers blue which would highlight the low spots.

[70CB750]

+1 on the glass and lapping paste

[madmtnmotors]

+1 on the glass and lapping paste

+2

I have had the best results with the Permatex brand water based lapping compound. Spritz it with a little water and mix it into a paste, then spread it out on the glass. I had happened to have an 18" by 30" sheet of tempered glass 3/8" thick. I've done three heads this way so far (including the head on the wife's Cavalier). I am learning the value of having a machine shop shave the head! My arms are sore by the time the head is smooth, usually about four to six hours on the glass.

[pdeg]

Noticed on the Cycle X site with the cam chain tensioner .. there appear to be washers
on either side of the bottom pulley axle.  Presumably to centre the bottom pulley.

http://www.cyclexchange.net/camshaftpage.htm

I did not pull any, and did not get any on the new tensioner. 

Do you guys have them.  The book does not talk about them either.

Are they a good thing.

Cheers
Peter

[flybox1]

This end of the bracket is formed, and does not need washers. The washers from the picture on the site must be for between the bracket and rollers.....Check your tensioner for them, installed..

[pdeg]

Tx for that... Mine looks like that too.

BTW... checked out some of the pics on that link.  I like the black paint ... what brand ?
And the tent was a nice idea too..

To keep the idiot questions coming ....

Was looking at this photo on the service supplement for the F2. ..
http://manuals.sohc4.net/CB750F/HSMCB750F.pdf

and they talk about stud packing ?  I pulled some of them out of mine when I stripped it.  Did not get any in
the gasket kit....   Suggestions.. ?

Just use O rings in there ?

[madmtnmotors]

they talk about stud packing ?  I pulled some of them out of mine when I stripped it.  Did not get any in
the gasket kit....   Suggestions.. ?

They look like little rubber "barrels". Every kit I ever got had eight of them. The early K models did not use any. The early F and later K models used eight. The later F models only used four. They go around the knock pins at the oil return studs.

[Davidov]

I left the dowel orings out,  They really arent necessary


check out brandEns 'leak free' top end build.
excellent info here  http://forums.sohc4.net/index.php?topic=107040.0

You left out the 4 5.5x3 o-rings?

They look like little rubber "barrels". Every kit I ever got had eight of them. The early K models did not use any. The early F and later K models used eight. The later F models only used four. They go around the knock pins at the oil return studs.

Jim at Cycle X stated the cylinder stud packing rubbers are not necessary when using a MLS headgasket.

[flybox1]

I left the dowel orings out,  They really arent necessary


check out brandEns 'leak free' top end build.
excellent info here  http://forums.sohc4.net/index.php?topic=107040.0

You left out the 4 5.5x3 o-rings?

They look like little rubber "barrels". Every kit I ever got had eight of them. The early K models did not use any. The early F and later K models used eight. The later F models only used four. They go around the knock pins at the oil return studs.

Jim at Cycle X stated the cylinder stud packing rubbers are not necessary when using a MLS headgasket.

No, I was referring to the stud packing dowels.  I left those out.

[pdeg]

I left the dowel orings out,  They really arent necessary


check out brandEns 'leak free' top end build.
excellent info here  http://forums.sohc4.net/index.php?topic=107040.0

You left out the 4 5.5x3 o-rings?

They look like little rubber "barrels". Every kit I ever got had eight of them. The early K models did not use any. The early F and later K models used eight. The later F models only used four. They go around the knock pins at the oil return studs.

Jim at Cycle X stated the cylinder stud packing rubbers are not necessary when using a MLS headgasket.

No, I was referring to the stud packing dowels.  I left those out.

Can I use O rings ? ... or will they not fit..
I "could" try and re-use the old packing...  but as you said .. I cannot see what they do

[Davidov]

Cleaning up the top of the barrels.   400 grit sandpaper on a file..  I presume that the dark bits are the low spots.
Can see the  work of the bloke that had it to bits previously    Any thoughts on this idea ?  For all of the hassle
should have asked the bike shop to clean and face this part..

Like flybox said, that's a little harsh for the surface.
I use one of these green bristle discs, made by 3M. Green is the least abrasive, they have yellow too, whic is a little stiffer.


Keep up the good work, and don't be afraid to ask questions! I'm doing a F3 engine as well.

[madmtnmotors]

Can I use O rings ? ... or will they not fit..
I "could" try and re-use the old packing...  but as you said .. I cannot see what they do

O-rings? The stud packing seals at the oil return stud "knock pins" are almost 1/2" tall. Where would you find an o-ring like that? These were only used in later model F and K models and were not even thought of yet during the early years (pre '74 I think). This was an effort to try and prevent oil weeping from these return passages at the head gasket. It was a band-aid to try and address oil weeping from the head gasket at these locations. I've always used them, but as has been stated more than once here already, the early engines don't even have the cutouts for the knock pins, let alone the "stud packing". So if you were building an early engine you would not even have the option to use them at all.

You would have greater success preventing this oil weeping by ensuring the head and corresponding cylinder mating surfaces are flat. Don't see how that can be achieved with something that has a footprint as narrow as a file...

[garyS-NJ]

I am with you on studs, I tried to get one out and since it did not work, I figured they are strong enough

What I did for rusty studs - the 4 exposed - I smeared them in vacuum grease and covered the length with shrink tubing.  With cylinders in place I used some hondabond to block the water from entering the stud hole; the idea is that water will not get lower than the head gasket level.  If it will work, I don't know.  That's for the next owner to call me names for 

hey Prokop - that sleeving idea is interesting as I'd like to do something with my F3 to keep water out of that area during winter (bike lives outside and I don't want water to freeze in there).  Cycle-X presses and machines a brass or bronze sleeve in the cylinders to keep the water out.  so you got your rubber shrink sleeves to shrink down to fit just close to the cylinder stud holes and then a dab of hondabond to seal?  Why vacuum grease instead of any other grease or filler (and why grease at all under the heat shrink tubing).  then did you smell anything cooking when you ran it?  how many miles since this mod??

[flybox1]

^ This is not done to keep water out, but to keep the stud, and its passages from rusting.  Those studs there are exposed to the elements...all the time.
Vac grease has high temp resistance, so it wont run out, and it'll keep water out/rust from forming between the sleeve and stud.

[70CB750]

I couldn't say it better myself:)

I did not finish my build yet,  and the only way to see if it works would be to take engine apart again.

It can only improve things and it was cheaper than Cyclex.

[flybox1]

I couldn't say it better myself:)

Brilliant idea, Prokop, I just wish you mentioned it before I buttoned everything up 

[garyS-NJ]

so it's really anything to fill the void and seal it up.  I was pondering what to do with mine and like your idea too.  will have to play with the shrink sleeving tho or look for a metal sleeve.  lucky for me I have a basket motor apart in my basement (bottom end for my bike is 10 miles away in a garage.).

[flybox1]

just remember its gotta be thin enough to fit through the stud holes..