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Discussion Starter · #1 ·
Hi!
I'm fairly new to the whole bike thing, so I thought it was a good idea to register here and try to keep up with all the advice.
I bought a 1977 Honda cb750f earlier this month and gradually want to change a couple of stuff. This week I noticed 2 of my 4 connections between my air filter and carburator were badly connected. The rubbers didn't slide to the end. I thought it would be the easiest if I loosen them all and connect them all one by one. Off course this didn't work... I can't seem to connect them. Anyone have any tips?

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Loosen the air box, remove the bolts if you have to. That will give you a bit of wiggle room. Spray a bit of wienerschlippen on the boots. If they are deformed from being squished, you will need to use something from your tool box to help work the edge of the boot over the carb don't use anything sharp. Warm them up with a hair dryer if it's cold out. Don't spray the wienerschlippen and use the hair dryer at the same time.

Second glance at the photos. You'll need to remove the air box to reinstall the boots into the box.
 

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first things first - are the boots hard? If they are go boil them in a mix of wintergreen oil and water - this will soften them up again for a while. Typically the boots shrink over time which is why nearly every cb750 you see with a stock airbox will have an ill fitting pair of air intakes.

First off get the part number off the airbox and look up to make sure you have the correct one. I believe it is embossed on one of the sides of unit. Because of the change in carbs from 69-76 to 77-78 there are two different ones.

The important part is not that they fit completely over the carb bellmouth, but that they fit and seal without pinching in the airbox or otherwise distorting the velocity stack. #3 def has an airleak but #4 looks alright. If you can't get the old ones to fit, new ones are available and are $6.78 per v-stack, part number 17253-405-300:

Honda Motorcycle Parts | Honda Parts Finder | Honda Parts Direct Palestine, TX (888) 446-6325
 

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Discussion Starter · #4 ·
OK, thanks for all the great info guys! I've got some spare time this weekend and I'm gonna try this.
They are indeed very hard so I hope the mix with water and oil helps. Is there something I got to keep in mind when removing the airbox? I don't want to screw up other stuff while fixing this
 

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You can heat those rubbers up with a heat gun to get them soft again. They will harden up when they cool but you should be able to get them back on the air box / carbs.

Good idea to wear welding gloves when you do this. Don't worry - you wont burn the rubbers with the heat gun.
 

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You can heat those rubbers up with a heat gun to get them soft again. They will harden up when they cool but you should be able to get them back on the air box / carbs.

Good idea to wear welding gloves when you do this. Don't worry - you wont burn the rubbers with the heat gun.
the wintergreen oil is the better solution here, it is used in the copier industry to make some of the rollers soft again for a good long while. Plus it may help them to swell back to original size. They won't harden when they cool - you'll probably get another 2 years out of them. then again, new ones are cheap, I mean really cheap.

When you remove the airbox, take it outin sections. Too many people (including yours truly) tried to remove it as one piece and learned the hard way that is just a recipie to break stuff. don't bend those compression collars, once they get a kink in them they won't seal.
 

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you either don't have a 1977 model or you have the wrong carbs on the bike. which could explain why the boots aren't going on properly.
I can tell you that from your photos those are not 1977 model carbs.
 

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you either don't have a 1977 model or you have the wrong carbs on the bike. which could explain why the boots aren't going on properly.
I can tell you that from your photos those are not 1977 model carbs.
I think this is the winner. Looking at the pics again there's a massive gap between the rubbers and where they should slot into the airbox holes - far to big to simply be shrinkage.

Wrong carbs / rubbers / airbox....or a combination of the three.
 
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