Topic: Frame diferences between CB750 and 750 Super sport

[CR750REP]

Building up a CR750 street replica. Just missed out on a '78 frame but just got a lead on a '76 750 Super Sport frame. I know the steering geometry was improved on the Suprer Sport but  are there any other differences I should know about. Not concerned about the side cover tab recepticles, or any other bodywork fasteners, don't need them. Will the engine mounts line up like the CB? Appreciate any help offered.

Thanks...

[jonbuoy]

I have a K3 engine in my 77 supersport if thats any help.  I believe the rear frame rails are longer on the supersports?  Also it doesn't have the triangular rear frame section as the pegs are mounted on aluminium brackets.  I looked at making mine into a CR replica but I think a K frame would be better - just my newbie opinion.

[CR750REP]

Yeah...That's a big help. At least I know the enine will fit. I figured it would, but now I know. The rear triagular portion of the frame won't matter much as I will be fitting rear sets. The longer rear frame rails will help as I want a slightly longer seat section anyway. Sounds good so far...Thanks.

[Clyde]

The 76F/SS frame  does not have the aluminium brackets for the foot pegs but apart from that is not much different to the 78F/SS and IMHO is a better handling frame than the K series.
The steering angle is slightly different on the F series and it would be best to use a triple tree and clamp from an F rather than a K. I have used a F triple tree on a K and it makes it a bit quicker steering, but doing the opposite would be going the wrong way.
Regds Clyde

[CR750REP]

Thanks a lot for that bit of info. This just keeps getting better all the time.

[Ricky_Racer]

The '75-76 F frame is 3 inches longer than the '75-76 K from from the shock mount centerline to the end of the upper rails. The F upper rails are 1/4 inch narrower at the absolute rear.  RR

[CR750REP]

Thanks RR...Great help.

[Geeto67]

the F frame will have the mounts for the disc brake master cylinder also (bolts to am aluminum brakcet on the right side). If you are using a 76 F frame get the swingarm too and run the rear disc setup (k swingarm will not work with the rear disc without welding some brackets).

[Jonesy]

Here's the layout for the K frame:



Anyone have the factory drawing for the F frame?

[Retro Rocket]

Did anyone have a pic of the layout for the "F" frame.?

Mick

[Jerry Rxman Griffin aka MuthaF'er]

Are you watching this CR replica frame on EBay?

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=190273918413&ih=009&sspagename=STRK%3AMEWA%3AIT&viewitem=

[Retro Rocket]

Yes i saw that, still wiping the drool off my chin... . I was after the corresponding pick to the one above for a comparison. I just found {quite by chance} a perfect condition K2 frame fo $200 Aussie dollars, not far from where i live, been in storage for 30 years......couldn't believe my luck 

Mick

[lordmoonpie]

Depends how close you want to get to a replica CR750. If you take a K series frame there's about 20 small modifications to make to the frame to match the CR spec more or less, much more with the supersport frames. That's assuming of course that you don't chop the steering head angle like the French Endurance CR750s then you're into big frame money...

[Ricky_Racer]

Japauto changed the steering head angle on their Bol d'Or CB750's???  Do you happen to know the revised angle?  Thanks.  Ted

[EvLoutonian]

G'day Mick

How'd you go with with this project in the end?

Cheers!
Ev in Melb

Yes i saw that, still wiping the drool off my chin... . I was after the corresponding pick to the one above for a comparison. I just found {quite by chance} a perfect condition K2 frame fo $200 Aussie dollars, not far from where i live, been in storage for 30 years......couldn't believe my luck 

Mick