Topic: CB750K4 Stock Airbox Doesn't Align Right Side

[Yoshimitsuu]

Good evening all,

In my quest to get this CB750K4 back to it's glory, I found an airbox and bought a K&N air filter which I am trying to fit onto the bike. My carburetor went in no problem and to be honest even the new air box rubbers that I bought went into the carbs just fine and are clamped. The problem I am running into is that while the left side bolts into the frame just fine, the right seems to be off about 1/4" behind. I tried to push the carburetor down and to pull the airbox in that I saw in another thread but it doesn't seem to want to settle into a position where I can get that right mounting bolt on. Any tips on how to get both ends of the airbox bolted into the frame?  Should I drop the air filter part of it and focus on aligning the top part first and then bringing the filter part back? I'm getting really sweaty and am losing control of my mouth help!

[seanbarney41]

yeah, that is exactly it, put the top half in first.  dont put the bottom half on until last

[ekpent]

 Turning the rubber manifolds in the airbox may make a little difference also. Definitely have to be just right for the carb to head rubber boots.

[Yoshimitsuu]

So I was able to bolt the air box onto the bike on both sides. However, I’m not super I did it the correct way. My air box seems a bit lopsided. I’ll attach a picture below.

Any ideas why this could be? There’s no obstruction behind and I made sure the air box rubbers were all angled in the same direction and are clamped to a snug fit. The only other thing I can think of are the rubbers from the engine to the carbs but I installed them in the correct order (1-4 left to right looking down) as I removed them. Any ideas?

[Bankerdanny]

The airbox on my '76 F seems a bit more level than yours.

Are your connector rubbers properly seated in the holes in the box?

[Yoshimitsuu]

The connector rubbers are completely over the carb. I also checked the rubbers from the carb to the engine and loosened the clamps and rotated them until they were flush then clamped down again. The air box to carb boots are also not lopsided but completely over evenly. I’m so confused. It’s bolted on but lopsided and if it’s not a big deal I won’t worry about it but I just want to be 100%

[Bankerdanny]

You need to also make sure that the box side is correct. The connectors have raised grooves in them that seat around the holes in the box. Installing a box with older stiff rubber connectors can cause them to pop out of the box, which will impact alignment.

The seam for the 2 halves of the box should be roughly parallel to the top of the engine case.

[Yoshimitsuu]

Judging by the picture that you posted compared to mine I think it’s as you said: my box to carb boots are backwards. In your picture the shorter side is towards the top but on mine it’s towards the bottom. When I get home I’m going to flip them. Thanks for the picture!