I am having trouble fitting this air box, and rubber hoses which connect to the carbs, onto this bike. I had them on, but at least one of the hose clamps was not really in place. Now, after reading, it seems the hoses for the K7-K8 carbs are different from the earlier ones. Bigger diameter, I think. And so....I am ready to order the correct hoses and clamps. But now I am not sure they will fit this air box. See what HondaMan told us in 2011 below with underlining added.
My question: How can I tell if my air box is correct - or incorrect - for my K8? I find no part numbers on this air box. I *think* the hoses I have (and certainly the clamps) are incorrect for this bike. Clamps certainly are too small. Hoses sort of fit, but they are very tired. See attached pics. This is the only writing I can find on this air box. Also, I wonder if the earlier bikes' air boxes had this large-ish air hose connection on the tops. This connects to a gizmo (technical term) under the battery box that also connects to the valve cover.
It would be great to have a parts list for this bike, or these CB750s. And a complete set of exploded diagrams.
Here is what HondaMan said in 2011:
Keep these things in mind when kitbashing parts:
1. The "K" engine carb hoses (K0-K6) are longer than the ones on the 1976 and later bikes.
2. The airboxes on the 1976 and later bikes have shorter hoses to the carbs than the K0-K6 airboxes, and they also have a wider mouth at the carbs if the "F" engine had PD carbs. If the "F" engine had 7A carbs, they are the same dimensions as the earlier K0-K6 carbs (same bodies), but these were just on the F0-F1 bikes.
3. The F2/3/K7/8 airboxes have bigger holes where the hoses fit, too, so the K0-K6/F0/F1 hoses don't fit those airboxes. The F2/3/K7/8 airbox hoses are also shorter than the earlier ones.
So, for example...if you have a K1-F1 engine with the stock carb hoses between the head and carbs, and are using the early-style carbs (with ID numbers like 657A, 657B, or 7A stamped on them), then use the K1-K6 style airbox and all will fit fine, even in the frame mounts.
However: the airbox hoses do shrink from the years. They are soft polyethylene-neoprene, which shrinks about 1% of its length and diameter every 12 months.
