Topic: older tank on a 78?

[gribbs]

is it possible to use the smaller tank on the 78?  The petcock is on the wrong side it seems, is there a way to modify it for use??

[scondon]

     Which smaller tank are you referring to and what 78 are you wanting to put it on? The petcock seems to be on the wrong side of what?  Maybe your question is a continuation of another post, where all bike particulars had been answered but sitting here by its self I have no clue which bike or parts you're tryin to mate up.

    More info please

[gribbs]

78k is my bike. This tank is from a 75 i believe, and the petcock is on the right side of the tank, whereas mine is on the left side (i mean if you were looking down from the top of the tank, as if sitting the bike lets say)

I like the smaller, older style, rather than the big 78 style, so

[Ryan 550k]

Ok, but what size engine are you running?  Is it a 550k?  750k?  Different size engine has slightly different frame so unless you tell these guys, they won't be able to help.  Also, what size bike is the other tank from?  Same size or different?  You mentioned putting on a smaller tank so I'm assuming it's from a smaller bike.
Just give more info

[KingCustomCycles.com]

I did that on this 550 but had to dent in the inside tunnel of the tank with a hammer and "massage" the frame at the brace area with the same hammer.  It was not as crude as it sounds.  I much prefer the older, rounded tanks on cafe bikes.  The tank was from an older CB750K, as I recall.

[scondon]

  As long as the petcock on the 75 tank is not banging into the carbs you can probably just use a longer(shorter?) fuel line to route from carbs to tank. Another issue may be the spacing between your seat and the end of the tank.

[mcuozzo]

I think he's asking if he can use an older 750 tank on a 78K bike.  The 77's and 78's have a bigger boxier style tank.  The 77 and 78fs have even bigger tanks.  I have a 77k and a 78f.

From what I've read using an earlier 750 tank is no problem.  As mentioned if the petcock is on the right (ie. the wrong side!) just use a longer fuel line.

I have a 74 750 Tank en-route to me as we speak.  I will test fit it next weekend and let you know if there are any issues.

One thing that seems to be different is the rear of the tank, so there might be a gap between it and the tank.  (oops scondon mentionted that first too!) I'm going to build a custom seat so I don't care about that.

I'll take pictures when I do the test fit.

Matt

[gribbs]

mcuozzo got me perfect - I am on a 78k and wanna fit an older style 750 tank to it

I know the seat/tank meeting spot will all have to be modified. The new seat will be a differnt length.

The 77-78k tank is bigger and longer, petcock on the left side. New fuel lines for sure needed.

Hmmm  I cannot decide if I want to go with Carpys seat section for the 77-78 or get a used older tank and a cheaper seat section from ebay.....