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Technical/Restoration Support

6. Fuel System

Early Production Tank - 1st Run - Underside View - Note absence of round quarter sized
"dimples" to clear carb cable tops.  Note lack of relief in the "square-D" areas on each
side of tunnel.  In both cases, fouling of carb cables occured.  This is the tank the Japanese
call the "nine-teener."  Later tank's capacity was reduced to 17 litres, due to bilateral
relief to solve the carb cable fouling.   


Later "4-dimple" Tank - 17 litre - Who has a picture of a mid-run "2-dimple" Tank ?


19litretank 002.jpg

Fuel Cocks

Late style "rear feed" fuel cocks - Left is a period original.  Right is a later mfgr date. 
There are a number of differences - How many can you find ?
Who knows at what VIN these began being used ?


Early Fuel Tap - short neck
Early Petcock.JPG

Late Fuel Tap - long neck
Late Petcock.JPG



Here�s another bit of trivia, well not really trivia but most will never venture to find out that there are at least 3 different castings used for
Honda�s early production gas caps. (That�s fuel caps or petrol caps to us plebs out in the territories). Yes, I�m only referring to the early
type caps that have the Phillips head screw holding the seal and breather plates in place as used on K0 and K1 models.

Feast your eyes on the picture. If you know the history behind these different castings please make a contribution. I can say one thing though, 
2 of these caps use the small nylon spacer that goes between the pin and cap where the cap mounts onto the tank. The third casting type is
ever so slightly narrower than the other two and that small nylon spacer doesn�t fit when trying to mount the cap. Yes indeedie, this is an
interesting find me little hearties. Does this mean that there is an early cap casting for sandcasts, early wrinkle tanks or what? Cheers KP






For those that didn�t know, there are in fact three types of  �Sandcast� air cleaner box which I have simply referred
to as the 2 hole and the 3 hole air cleaner box. This is simply stated; early sandcast air boxes are held on to the frame by a bracket
which attaches to the air box top by 2 fixing points, whereas the later type has 3 fixing points. The 2 hole air box also has 2 variations

(identified by Chris Rushton). The variation is that very early 2 hole air boxes have no frame indents and this is easily seen in the

red air box (bottom) picture. No one can say with authority at what VIN these changes were made.


In relation to the 3 hole fixing arrangement, this modification was carried over into later production years and remained on all future

SOHC CB 750 models. Yeah, yeah I hear the more knowledgeable say. But how many of us know that there are other significant

differences between the three air boxes. Yes indeedie


Unless you have had them side by side or possess an early and later type, you�ve probably thought that the bracket was
the only difference. Here are pictures of all air box types (tops only) which show the differences. I haven�t been able
to identify any differences with the bottom halves. Another difference is the brackets themselves. The 2 hole is not a cut
down 3 hole bracket, rather, there are subtle differences in the overall dimensions of each type. With a bit of work you could alter a 3
hole to match a 2 hole if you are stuck for an original. There may have been other variations with these early type air cleaner boxes

(as Chris discovered), but this is what we know to date. If you have discovered other differences please add to this contribution. Cheers KP


Aircleaner 2.jpg

Aircleaner 3.jpg
Aircleaner 4.jpg





Early Type Carbs with replacement/recall tops/adjusters


Carbs Early1.JPG

 Carbs Early2.JPG


Early #1 Carb - Note Long Choke Arm


Carbs Early3.JPG



"28" Cap with 6mm brass adjuster - These caps were recalled by honda due to sticking


28 Carb Top.jpg


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