Topic: Cb750k Carbs fall off of intake boots

[Jcoatain11]

I'm currently working on my 77 cb750. I have contrary to the common thread saying not to install pod filters... I did. I have jetted the carbs to run well that is not the problem. What it is, is that when the bike (and intake boots) get a little more heat in them the carbs fall out of the intake boots. I assume this is just because it doesnt have the back end support that the airbox provided. If anybody has any secrets or general advice to combat this, other than the obvious "go back to the airbox", I would greatly appreciate it! Thank you

[scottly]

You need to support the rear of the carbs; a zip-tie or bailing wire can work. This may be why some people can't seem to make pods work, while others have success.

[seanbarney41]

a 77?...sure you got the right year carbs, with the right year boots?

[Jcoatain11]

To my best knowledge they are the correct ones carbs. They are keihin pd41. The boots are the ones that were on the bike when I bought it. I'm not sure how to tell the difference between the different years as far as the boots go. I will try to the wire support, I'm just not sure how to do it cleanly. Again to my best knowledge the boots are the correct ones. They are a slightly hard, the carbs fit in them well. Should I still pursue softening them up? Or would that not help my case. Thank you again gents!

[dusterdude]

Pd41's came on 1978 models,iirc.not sure of they use different boots.

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[BenelliSEI]

Are the securing clips bottomed out (as tight as they can go)? Try a slightly smaller one to ensure they are really tight. I’ve noticed that <vintagecb750.com> sells a strap for linking/ bracing carbs with no airbox? No idea if they fit your model.

[Bankerdanny]

Make sure the carbs are fully seated in the rubbers. Heat from a hair drier or heat gun will help soften the rubber, then I use a very light smear of Vaseline or lithium grease on the inside of the rubbers helps quite a bit.

[Airborne 82nd]

I'm currently working on my 77 cb750. I have contrary to the common thread saying not to install pod filters... I did. I have jetted the carbs to run well that is not the problem. What it is, is that when the bike (and intake boots) get a little more heat in them the carbs fall out of the intake boots. I assume this is just because it doesnt have the back end support that the airbox provided. If anybody has any secrets or general advice to combat this, other than the obvious "go back to the airbox", I would greatly appreciate it! Thank you

The part # will usually gives you a clue if the parts are  interchangeable in this case at the cmsnl site numbers are
750k8 16211405000P
750k7 16211405000
I don't know what the P stands for.

Hondaman wrote this in a post a few days back
 Honda had to have Keihin make 2 different PD series of carbs, the PD41a and PD41b for these bikes (the "b" is California's version).So...first, determine which type of carb you have: there are 4 possibilities on the K7, depending on whether it is really a K7 or is a retitled late K7 that became titled as K8 (they were doing that back then). The 4 carbs are the PD41a, PD41b, PD41 (no letter) and PD42a (more often found on the F2 model)
 If you look up Exhaust in the site that  BenelliSEI posted you will find many brackets in chrome & black that will work for holding the carbs up.
 I had a big laugh picturing you going 60 mph and wondering why your bike was running like crap. Reminded me 1970 when I left work and my bike would not move looked down and saw my chain had come off.    Written in jest

[Dolomite]

I run velocity stacks so I don't have the airbox support either. I used stainless zip ties and ran one up on each side to the frame. Not tight or pulling, but snug so they can't slump down or move side to side

[Stev-o]

a 77?...sure you got the right year carbs, with the right year boots?

I think Sean has it,  dont the PD's have a slightly larger diameter? Wrong boots.