Topic: difference between 77-78 cb750 frame to older frames

[crxnug]

can anyone tell me the difference between a cb750 77-78 frames (even something minor) as compared to a earlier version,Any help would be much appreciated

[seanbarney41]

first of all, you have to be a little more specific...there are 5 distinct sohc cb750 frames k0-k6, f0-f1, k7-k8, f2-f3, and finally 750a

[754]

The late F has side stand relocated.
 Late frames are longer in back and have a shock mount offset , unlike early.
 Rear peg mounts are different, not sure about location vs early.
 Wiring tab welded on under tank..  F model has a few bungs welded on neck I believe..

 And a few frames, it might only be 77 ? Have a different type top front motor mount on Alternator side.
 Oil tank mounts are likely different , and top rear motor mount , kicker side is different.

[HondaMan]

The passenger-peg and pipe hanger "triangle" on the rear frame is also different, so it will not fit the popular rearset footpegs if making a race bike from it. Terrozi comes to mind...

The later frames make it slightly easier to remove/install the engine because of the right top rear engine mount change into a rectangular plate instead of the eralier triangle shape.

The later frames (F and K all)  sport a little longer wheelbase, with a slight difference in rake angle (more trail) at the triple tree.

The later frames have a different swingarm, not quite as strong as the early ones, but strong enough if you're not racing with it.

Very little of the welding on the 1975-later frames was done by hand: most was done by automated pattern welders. It is usually barely adequate, so if you strip the frame for painting, consider running a few extra beads on places like the steering head, rear frame upswing plates, [often] the sidestand mounting plate.

[BenelliSEI]

Also..... the 1977 cb750K frames have a removable engine mount, front, left (sitting on the bike), just below the #4 exhaust port. The usual welded lug, is replaced by a bolt on, fabricated mount. Strange, only that model, that year. Never seem an explanation. 1978 cb750K went back to the lug.

[HondaMan]

Also..... the 1977 cb750K frames have a removable engine mount, front, left (sitting on the bike), just below the #4 exhaust port. The usual welded lug, is replaced by a bolt on, fabricated mount. Strange, only that model, that year. Never seem an explanation. 1978 cb750K went back to the lug.

Oh, yeah! I forgot all about that! I've only ever seen one of them.