Topic: Gas Tank

[jcunningham80]

Will a 1971 CB750K1 gas tank fit a 1974 CB750K4?

[dagersh]

It should.

[tmht]

What year did they switch the petcock from the right side to the left side? It should "fit" but if the petcock is on the opposite side you are not going to be able to reach the idle adjustment easily, if at all because the petcock will be in the way.

[andy750]

Should fit. Petcock was switched from right to left after/during `75.

My K2 and K4 both have right side. K6 for sure had left side.

cheers
Andy

 

[.RJ]

Sort of on topic - will a 550 gas tank fit a 750?

[Swede]

The frame on the 550 is wider at the point where the tank fits on the front tank mounts.  I had to cut the studs down on my 550 to fit the 750SS tank.  I imagine that it would be possible to fit the 550 tank it just might take a little work.

[ProTeal55]

I had a K8 tank on my CB750 k2 when I got it.
I soon switched to era correct tank, although the petcock is on the left side.
Always wondered why it wasn't so easy to adjust the idle - now I know 

[.RJ]

The frame on the 550 is wider at the point where the tank fits on the front tank mounts

Thats an easy fix - just space out the f ront mounting rubber donuts to take up the slack.

I think it looks better, with the gas filler cap offset to the right - and while I'm building something fun...

[.RJ]

Sort of on topic - will a 550 gas tank fit a 750?

Still thinking about this... I did some reading here, and the 550F tanks are longer than the 550K tanks, and the 750F tanks are longer than the 750K tanks.   there's a fairly decent 550F tank  on ebay (i've got a 750 K1), and I asked the seller to measure it, and its the same length (21.5") overall, and what appears to be the same length from the mounting rubbers to the front of the rear mount (17.25").

Other than the spacing of the rubbers and the petcock location, which is no big deal to me, any reason why this wont fit right on? 

[.RJ]

Hump day bump! 

[Reagan]

The petcock on my 1973 750K K3 is on the right side. I found out by buying a used tank at the wreckers which has the petcock on the left side. Now I have to buy a 1975 or later 750K that needs fuel tank. It's an endless circle.

[Reagan]

This guy lists a 1974 CB750 tank but the picture shows the petcock on the left side.

http://cgi.ebay.ca/74-HONDA-CB750-CB-750-GAS-TANK-NICE-ORIGINAL-PAINT_W0QQitemZ170124689852QQihZ007QQcategoryZ35586QQrdZ1QQcmdZViewItem

This one lists a 1974 CB750 K4 and the photos also show the petcock on the left side. It sounds like this one is from a tear down so I would think the fellow knows the year of the bike.

http://cgi.ebay.ca/1974-Honda-CB750-CB-750-K4-Fuel-Gas-Tank-OEM_W0QQitemZ160131471214QQihZ006QQcategoryZ35586QQrdZ1QQcmdZViewItem

Do the position of the petcock change from right to left in 1974 and not in 1975?
Now the issue is as clear as mud.

[jaknight]

Hello Guys,

     I have a 1974 CB750 K4.  I guarantee you 100% that......... from the factory........... the petcock is on the right hand side of the gas tank.

     ~ ~ ~ jaknight ~ ~ ~

[nteek754]

Hey all I think its all about the early/ late model years like the late model 74 750K (sisters bike) is on the left  my original 74 750 was on the right   god rest its soul (I do still have pieces of it) on my 73 runner now but anyway   in my dealing I have seen  the origanal gas tank on a bike but the petcock was in the way of the idle  screw I really think that honda had to use up the old stuff and had more of some things then others  now also remember  when you go from the old settlement bowl style (right side) to the later style you also go to one gas line  just have to put a T in and run it to the left side of the bike (that is most of the ones Ive seen are single line feed  hope this helps good luck have fun Craig in Maine

[.RJ]

Sort of on topic - will a 550 gas tank fit a 750?

I thought I had this problem figured out - it just needed some clearance for the frame rails:

http://boostrot.net/gallery/d/6476-1/IMG_0631+_Large_.JPG

Then this evening, I tried to put the tank on, with the carbs - #$%* - the carb rocker arm things hit the tank at WOT, and there's no way the petcock will fit.

So the options are at this point to move the petcock mount forward (where the stock 750 tank petcock is) and clearance the outsides of the tank for the carbs.  Or go back to the 750 tank

I'll have to sleep on it - I really like the way the 550 tank looks on the frame but not sure it can be made to work.

[754]

I started a thread on running a 500 tank on a 750 before, it will show off the motor better.. but no one answered the thread.

Anyway, I know they wont fit.. a lot of differences. My plan would be to get a bad 750 tank and cut out the underneath part (lets call it the tunnel). Then cut out the 500 tunnel, but not all of it, then start fitting and trimming and tacking, and fitting, and trimming, bit of peening with a ball pien, tacking, a bit of trimming, swear a bit, lok at it get disgusted.. let it sit a few months.. etc, etc...

It would look good but I think an aircraft style cap would look trick , or may the Aluminum ones I made for Laverdas...

[.RJ]

Anyway, I know they wont fit.. a lot of differences.

Differences yes, but nothing that cant be 'fixed' with metal, time, welding and beer - like most things

I talked with a friend that does metal work on the side, and he thinks this is no big deal... so I'll give it a shot, and post some pictures.

[754]

You probably could make a few slits under the 500 tank and start bending stuff. The 500 has a more onepiece backbone on the frame, the 750 3 tubes in a triangle.


Modding the tunnel is way less work than building a tank, and none of it is visible..

I think the bike would be way sleeker looking, not the boxy look it has now..

[.RJ]

Yep, thats the plan - just make the underside fit.  It shouldnt take much more than the pounding I've done, just some cutting and welding.  The more I look at it, I think I'll just cut out the offending areas that foul the carbs, and have a set of 'boxes' welded in place so that there's clearance.

[Terry in Australia]

In 2001 I bought a "Japanese Market" CB750K4 from a guy who'd brought it back from Japan in 1976, (he was a school teacher, teaching English to business students) it fell over in the shipping container and there was a fairly big ding on the right hand side of the tank.

I'd bought a tank on Ebay a while earlier for 20 bucks, it too had the petcock on the right hand side, so I stripped it back and painted it in the K4 paint scheme. It was a funny tank, if you popped the cap you could see lines of "wrinkles" running down the inside, and it was a lot more "agricultural" than the K4 tank, but what the hey, it was in perfect shape under the PO's red enamel paint job, it looked good painted up, and I sold that bike shortly afterwards.

If I'd known what that Sandcast K0 "wrinkle tank" was worth, I'd have fixed that K4 tank that's still hanging in my garage, ha ha! Oh well............... Hey RJ, what's you K1 tank like? I might need one!Cheers, Terry.



 

[754]

Get that tank back!!

[.RJ]

Hey RJ, what's you K1 tank like? I might need one!Cheers, Terry.

I gave it to the metal working buddy - he's doing his own 750 restoration

[.RJ]

Well, here's what you gotta do to make a CB500 tank fit on a CB750.

[Terry in Australia]

Hey that's some good work mate, how about a larger pic so we can see how the tank looks on the 750? What did you weld it with, mig or tig? Are you going to seal it before you paint it? Good Work! Cheers, Terry.

[754]

Tank looks 1-2 oinches too high at rear in last pic...

I find it hard to believe that the 2 lower frame rails are not hitting the tank somewhere underneath..

[.RJ]

The work was done by a guy that does some metal work out of his garage - it was done with a TIG.  MIG would burn right through the metal (I tried that).

I find it hard to believe that the 2 lower frame rails are not hitting the tank somewhere underneath..

They were, until I did this: