As far as the OP question, not all "K" tanks are the same. The petcocks changed almost every year. The bung on the tank is actually 3 sizes, early ones 16mm, mid years 18mm, while the last '82 had 20mm sizes.
DATA SHEET LINKY . So you will have to get the tanks petcock to be positive it will interchange if not the same year. Also I am not even sure they are dimensionally the same.
rich wrote
The "K" and "F" tanks are the same. The "C" looks different.
Here's why I don't think that is a true statement...
I picked up a 81 CB750C without a tank.
Wanting to build a cafe' / drag style bike I was searching for a "F" or "K" style tank because I believe the lines are better suited for that look I was after.
Over on another CB750 Forum that taylors to "C" models specifically, I read several threads on the subject. Over and over they stated (with pics) that those tanks would not directly mount to the "C" frame.
Some reported having to change the front mount by trimming the rubber cushions, others had to fab an adapter plate because the rear mounting hole on the tank was too far back to line up to the frames hole.
I decided it was worth the effort and bought what was listed as an "900F" tank on e-bay... once I received it, it fit like a glove... front and rear lined right up!!
I later learned a few differerances that determined I had in fact bought a "82 CB750 K" tank.
(EDIT) "750K" and 79-81 "750F" tanks have emblem mounting plates with screw holes where the 82 "750F" has decals and a smooth sides.
Listed capacity for both thanks is 20L (5.3g) but the "K" reserve is 5L (1.3g) while the "F" is only 2.5L (0.66g)... although this could be do to the petcocks pick-up tube length.
Also, I think the "F" tanks are slightly longer, that is why the rear hole does not line up... and this gives them a more
slender look where the "K" tank looks more
stocky. To my eye the "F" tank seems to turn down a little more at the rear, and these are why the side covers do not line up if mixed between the two models.
Maybe with more pronounced knee dents in the sides on the "F" and think THAT is the reason for the reserve being less on the "F".
NOW, other than a lot of research on forums, and my sheer dumb luck, I have no way of verifying any of this, as I have only had the one tank in my hand. BUT there is a tank on e-bay right now that I am thinking of picking up as a spare to do another paint job on and swap for looks only. Problem is, I don't know if it will actually fit or be one like all the other described. To me it physically looks like an "F" tank.
81 Honda CB750C - Current Project
67 BSA Spitfire MkIII - Next Up (Full Resto)
81 Honda GL1100 - Bob / Cafe´
80 Suzuki GS750L - Bratstyle
72 Honda CB450K5 - Basket Case
73 Honda CB350F Cafe' (Gone but not forgotten)
Don't wait for opportunity to knock... kick the door down and drag the old harlot in!
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