Topic: 78 CB750k Tank Swap

[Mercer]

So I was cleaning out my tank when I realized it was beyond cleaning. The inside is rusted and it looks like someone tried to seal it at some point because there is a huge coating that is flaking as well. So, I need a new tank and I am fine with that since I wasn't a huge fan of the 78 tank anyway. My question is what other 750 tanks will fit my 78. I really like the 75-76 year tank and I can get a decent one for pretty cheap. Will this fit mine, I cant seem to find an answer elsewhere on the forum?

Thanks

[seanbarney41]

It will fit but there will be a gap between the seat and the tank.  Also the petcock may cause problems with the pd carbs

[Mercer]

It will fit but there will be a gap between the seat and the tank.  Also the petcock may cause problems with the pd carbs

Excuse my ignorance here if this is a dumb question but what exactly do you mean by a "PD" carb? I'm assuming that the petcock on that year tank doesn't flow enough fuel for the carbs?

[Bankerdanny]

The carb's used on the 77-78 750k and the 77-78 550K are PD series carbs, I forget the actual models, but I think the 550 versions are PD44 and the 750 are PD46. The numbers are stamped into the manifold on the #4 carb side.

I think the issue Sean is referring too is potential interference between the outputs from the early style K tanks and the tops of the later style PD carbs.

[Godffery]

Your easiest swap would be the F model tank.   Mounts & petcock style & location are the same. 

[seanbarney41]

Your easiest swap would be the F model tank.   Mounts & petcock style & location are the same. 

Goddfrey, is that tank for sale by any chance?

[Bankerdanny]

Jeff, that might be the easiest swap to make, but it is the hardest tank to find next to a K0 wrinkle tank.

[Godffery]

 Here are a couple:
https://www.ebay.com/itm/Honda-Cb750f-Super-Sport-Gas-Tank-Cb750-Cafe-Racer/183376345763?hash=item2ab214faa3:g:dNoAAOSwX05bcPJj
https://www.ebay.com/itm/Honda-Cb750f-Super-Sport-Gas-Tank-Cb750-Cafe-Racer-Needs-Cleaned-And-Lined/183376346849?hash=item2ab214fee1:g:fZIAAOSwjwNbcPPm
 Also, I may be able to locate one threw my local Moto contacts.

[Bankerdanny]

Here are a couple:
https://www.ebay.com/itm/Honda-Cb750f-Super-Sport-Gas-Tank-Cb750-Cafe-Racer/183376345763?hash=item2ab214faa3:g:dNoAAOSwX05bcPJj
https://www.ebay.com/itm/Honda-Cb750f-Super-Sport-Gas-Tank-Cb750-Cafe-Racer-Needs-Cleaned-And-Lined/183376346849?hash=item2ab214fee1:g:fZIAAOSwjwNbcPPm
 Also, I may be able to locate one threw my local Moto contacts.

I suppose I should have said not easy to find for reasonable money.

The first one looks useable, the second is rusted crap, and yet still the seller wants $200 for it.

[Godffery]

Here are a couple:
https://www.ebay.com/itm/Honda-Cb750f-Super-Sport-Gas-Tank-Cb750-Cafe-Racer/183376345763?hash=item2ab214faa3:g:dNoAAOSwX05bcPJj
https://www.ebay.com/itm/Honda-Cb750f-Super-Sport-Gas-Tank-Cb750-Cafe-Racer-Needs-Cleaned-And-Lined/183376346849?hash=item2ab214fee1:g:fZIAAOSwjwNbcPPm
 Also, I may be able to locate one threw my local Moto contacts.

I suppose I should have said not easy to find for reasonable money.

The first one looks useable, the second is rusted crap, and yet still the seller wants $200 for it.

Yes, anything that is ready to use is gun'a cost 2 er 3 times that.  The way I figure it; We ether pay up front, or in the long run. 

[Bankerdanny]

Here are a couple:
https://www.ebay.com/itm/Honda-Cb750f-Super-Sport-Gas-Tank-Cb750-Cafe-Racer/183376345763?hash=item2ab214faa3:g:dNoAAOSwX05bcPJj
https://www.ebay.com/itm/Honda-Cb750f-Super-Sport-Gas-Tank-Cb750-Cafe-Racer-Needs-Cleaned-And-Lined/183376346849?hash=item2ab214fee1:g:fZIAAOSwjwNbcPPm
 Also, I may be able to locate one threw my local Moto contacts.

I suppose I should have said not easy to find for reasonable money.

The first one looks useable, the second is rusted crap, and yet still the seller wants $200 for it.

Yes, anything that is ready to use is gun'a cost 2 er 3 times that.  The way I figure it; We ether pay up front, or in the long run. 

Which is why the useable F2 tank I picked up at Mid-Ohio last month for $140 is the 2nd best deal I have made on SOHC4 stuff after the 750F Lester I just got for $100 shipped.

[Mercer]

Here are a couple:
https://www.ebay.com/itm/Honda-Cb750f-Super-Sport-Gas-Tank-Cb750-Cafe-Racer/183376345763?hash=item2ab214faa3:g:dNoAAOSwX05bcPJj
https://www.ebay.com/itm/Honda-Cb750f-Super-Sport-Gas-Tank-Cb750-Cafe-Racer-Needs-Cleaned-And-Lined/183376346849?hash=item2ab214fee1:g:fZIAAOSwjwNbcPPm
 Also, I may be able to locate one threw my local Moto contacts.

If you can track one down in your circle I'd be willing to purchase one, I was already eyeing the F tanks but they are always so expensive.

[SOHC4 Cafe Racer Fan]

I'd recommend going with a CB750F tank 75-77.  IMO a better looking tank than the 77-78 CB750K tanks.

[Godffery]

I'd recommend going with a CB750F tank 75-77.  IMO a better looking tank than the 77-78 CB750K tanks.

Agreed. Also; if budget is an issue, using anything stock that's made to fit will be more cost efficient then building a custom application or modifying something to fit.
 I'll put the word out for you and LYK.

[Mercer]

I'd recommend going with a CB750F tank 75-77.  IMO a better looking tank than the 77-78 CB750K tanks.

Agreed. Also; if budget is an issue, using anything stock that's made to fit will be more cost efficient then building a custom application or modifying something to fit.
 I'll put the word out for you and LYK.

No worries, I actually ended up snagging a used 78 Super sport tank for around 200. Since all the mounts were the same I figured it was a good call and it wasnt a bad price. I do appreciate the advice, that was a good call. I can post some pics once I get it. My bike is still very early in the build process. I'm in the get it running stage lol

[Godffery]

I'd recommend going with a CB750F tank 75-77.  IMO a better looking tank than the 77-78 CB750K tanks.

Agreed. Also; if budget is an issue, using anything stock that's made to fit will be more cost efficient then building a custom application or modifying something to fit.
 I'll put the word out for you and LYK.

No worries, I actually ended up snagging a used 78 Super sport tank for around 200. Since all the mounts were the same I figured it was a good call and it wasnt a bad price. I do appreciate the advice, that was a good call. I can post some pics once I get it. My bike is still very early in the build process. I'm in the get it running stage lol

Groovy! 
I found a couple locally and the prices were in the $250 to $400 range so I'd say you'r do'n pretty good on that one if it's anywhere close to being ready to use.
 Post some pix of it on, when you get a chance.   (inquiring minds want to know)    

[Mercer]

I'd recommend going with a CB750F tank 75-77.  IMO a better looking tank than the 77-78 CB750K tanks.

Agreed. Also; if budget is an issue, using anything stock that's made to fit will be more cost efficient then building a custom application or modifying something to fit.
 I'll put the word out for you and LYK.

No worries, I actually ended up snagging a used 78 Super sport tank for around 200. Since all the mounts were the same I figured it was a good call and it wasnt a bad price. I do appreciate the advice, that was a good call. I can post some pics once I get it. My bike is still very early in the build process. I'm in the get it running stage lol

Groovy! 
I found a couple locally and the prices were in the $250 to $400 range so I'd say you'r do'n pretty good on that one if it's anywhere close to being ready to use.
 Post some pix of it on, when you get a chance.   (inquiring minds want to know)   

Will do as soon as it gets here. I got to hear it run for the first time yesterday. Carbs were spewing fuel so tearing it apart again but it was a big win to hear it run. Hopefully I can just replace the needle seats and be good.