Topic: I need an opinion from experienced welders...re: CB750 gas tank

[MCRider]

My gas tank i was going to use on my project is likely unusable. I wanted to convert from a right side petcock to a left side petcock. The unusable tank has the left side bing style petcock.

My original gas tank has the 2 screw, right side pet cock. So...

Could the right side mounting be welded over to close the holes and...

Could the bung be cut out of the useless tank and welded into the good tank?

Is there enough material of appropriate thickness to make these kinds of changes?

I have a good welder, but I thought I'd ask around too.

If so, I think this might be the quickest and easiest way to accomplish my goal, without shopping for another tank and adding to my inventory.

I really want to decrease the amount of stuff in my shop, not increase it.

[754]

Check the area arounf the bung, it maybe a wider spot on that portion of the tank, where the bung goes....that the early tank may not have.

 Should be doable though..

[MCRider]

Check the area arounf the bung, it maybe a wider spot on that portion of the tank, where the bung goes....that the early tank may not have.

Should be doable though..

Thanks, I'll look again at those areas. IIRC there is a flat spot on the right side where the petcock goes. There is a matching flat spot on the left side as well, so I think that will cover it.

[750Caferider]

If you can take your tank and bike to the welder!  If not photo the hell out of the area so that he has a visual reference, also measure everything twice and mark it out or scratch with an awl.

Cheers!

[bucky katt]

i think that even with the skills i have with a welder, i'd take it to someone to braze the new petcock bung into the tank. the sheetmetal in those tanks is awfully thin in spots to weld i think. i'd be afraid of blowing holes in it, of course, i also dont know how to tig weld.

[MCRider]

If you can take your tank and bike to the welder!  If not photo the hell out of the area so that he has a visual reference, also measure everything twice and mark it out or scratch with an awl.

Cheers!

Yes I'll definitely not make an "out of sequence" mistake again. What I had done was de-rust the tank, had the final paintjob painted, then let it sit on a shelf for 9 years, where it rusted out. (I had not properly conclude the de rusting process and the insides were just bare metal.)

This time, I'll wait till the engine and carbs are in the frame, mock up the tank, maybe throw the whole thing on the trailer and take it to the welder to make sure the bung goes where it needs to.

Then get it painted.  My biggest concern is just that its possible, and I see no reason why not.

I'm excited about this idea. I am obssessed about having a left hand petcock. My original tank doesn't have a spot of rust anywhere inside or out. It does have a tiny dent but bondo will fix that.

[Jim F]

you could send it down and I could Laser weld it
Let me know

Jim

[masonryman]

In one of the welding shops I used to work in, we soldered the pin holes but welded all other mods in fuel tanks. if you try it your self put a shop vac in the gas fill hole to keep fumes from building.

I am just up the road in Muncie you could bring it by the body shop if you don't want to try, or if you o try and have problems.

A link to some pics of a current project
http://s892.photobucket.com/albums/ac125/rmherndon/

[MCRider]

In one of the welding shops I used to work in, we soldered the pin holes but welded all other mods in fuel tanks. if you try it your self put a shop vac in the gas fill hole to keep fumes from building.

I am just up the road in Muncie you could bring it by the body shop if you don't want to try, or if you o try and have problems.

A link to some pics of a current project
http://s892.photobucket.com/albums/ac125/rmherndon/

Thanks for the offer! I was wondering where Selma was, Muncie clears it up.

I've been using a shop for my other welding issues and may stay with them, personal reasons..

I won't be doing it myself for sure.

I'm still waiting on the final analysis of the leaking tank. Small chance it is salvageable. But the more I think of it, I'm liking the idea of just switching the petcock on the good tank.

I'll let you know.

[MCRider]

you could send it down and I could Laser weld it
Let me know

Jim

Thanks for the offer. Just curious where "down" is.   

[masonryman]

how far down, that could get deep

[754]

a couple more thoughts..
 You can use stocker on the other side, but  on/reserve pattern will be reversed, and you have to make a rectangular plate.

 Be careful rewelding a bung, often they have a lip that fits into the hole, plus a slight flange, that makes welding easier than welding a bung flating in a hole (easey to end up crooked) What I mean is the fresh bung should be bigger than the hole, easier to weld, and squares itself up..

[MCRider]

a couple more thoughts..
 You can use stocker on the other side, but  on/reserve pattern will be reversed, and you have to make a rectangular plate.

 Be careful rewelding a bung, often they have a lip that fits into the hole, plus a slight flange, that makes welding easier than welding a bung flating in a hole (easey to end up crooked) What I mean is the fresh bung should be bigger than the hole, easier to weld, and squares itself up..

Already bot a new left hand petcock, would like to use it.

When/if I ask them to cut the bung off the leaker, I'll ask them to give me as much metal as possible for the next welder to work with.

[754]

You may be able to slip a holesaw (less pilot) over the bung to cut it.
 just remember its easier if the bung or part of it is a bit bigger than the hole.. that why you maghine a small lip into it.. so lip goes in the hole and the wider portion stays outside the hole.

[MCRider]

You may be able to slip a holesaw (less pilot) over the bung to cut it.
 just remember its easier if the bung or part of it is a bit bigger than the hole.. that why you maghine a small lip into it.. so lip goes in the hole and the wider portion stays outside the hole.

Understood, thanks!