Topic: Petcock is on the wrong side, but dang its a cool tank.

[78_SaltLick]

I have a 1978 CB750K, I want to replace the big gas tank on it with an earlier model cb750, cause they are smaller and will work better with the clearance on my clubman bars i put on.  I just went down to the cycle salvage yard and after talking with the man who was quite nice, he parted with a "72" CB750K gas tank, the color was orange sparkle, super sweet looking, not a dent on it.  He gave it to me for $10.00...petcock and all. Whats wrong with it? Nothing except the inside is solid rust, goo and dirt and will need a really deep cleaning. so i just went out and looked and yeah, the petcock is on the wrong side... for a 78.i didnt even notice that when i bought it i was soo happy to get it for $10. Can i just re-route the fuel supply to go to the other side? Or is there more to it than that? If its quite a pain in the butt, ill just resell this one, and buy a 75 or 76 where the petcock is on the left side. Also the petcock on this one has two nozzle things coming off of it, on my current 78 it only has one tube going into it, whats the second one for? Thanks again guys.

[Bob Wessner]

The earlier bikes had two lines, one line fed carbs 1&2 and the other fed 3&4.

[Einyodeler]

You can go to a hardware or auto parts store and buy a Y fitting that fits the fuel line and run the two lines into one,then simply reroute the line from the other side.

[78_SaltLick]

The earlier bikes had two lines, one line fed carbs 1&2 and the other fed 3&4.

bob i cant see your bike too well in your avatar pic, but i believe i have the same tank you have there.

[Bob Wessner]

From your description I was thinking the same thing. Mine is from a K2, but the two outlets is correct for mine. Hope to repaint it and other parts sometime in the not too distant future.

[78_SaltLick]

yes it is the same tank. Thats a cool lookin year as far as the orange sparkle goes, and i like the black stripe. Man this tank is just filled with this black, thick, smelly rust/sludge stuff, im hoping this will all clean out, or im stuck with a $10 ashtray.

[kghost]

Pour about a gallon of MEK in it (then put cap back on) to get the sludge out.

Then you can work on the rust without making a mess with the acid.

[Bob Wessner]

When I cleaned mine, I tossed in a box of hex nuts along with some Marine Clean. Worked great, but getting all of them out was a pain. Someone here suggested a length of sash chain instead. Makes a lot of sense, will do the same thing and a lot easier to get out when your done and before you go on to acid etching.

[Einyodeler]

I used a big handful of nuts and tied them together with fishing line like a necklace,worked great and easy to remove when finished.

[Bob Wessner]

used a big handful of nuts and tied them together with fishing line like a necklace

Good idea, so simple, why didn't I think of that? Never mind, let's not go there.

[GeoffT]

So here is a green question from a newbie.

What does the marine green and a few nuts or sash chain (?) actually do? How does it clean the inside of the tank and is MEK the same as marine clean?

My tank doesn't appear to be to bad inside but I know it was stored for seven years with probably a good bit less than half tank of Petrol. It would be good to know how to make sure all was hunky dory inside the tank.

[Bob Wessner]

The bolts help stur things up during cleaning and mildly abrade the tank to aid in cleaning. I'm not familiar with MEK but I suspect it does the same thing as any good industrial cleaner/degreaser. If the tank was only half full, there is likely to be some rust on anything not covered with gas. How much, well, you won't know until you clean it, rinse and dry it out. You want to make sure there are not rust through points or pin holes before you go any further though.

[kghost]

Methyl-Ethyl-Tetone. I can't spell the damn name.

Its a medium rate evaporative solvent.

[Geeto67]

mek is the boil out acid that radiator shops use to clean the inside of rusty gas tanks....super casutic stuff. I use naval jelly because it is water soluble so it doen't hurt the envornment. For the scrubbers i find that bolt and nuts have to sharp an edge, bascally you want the stuff to get the jelly everywhere and let the chemical do the work, not the bolts do the work. I have a box of bb gun bebes that I use (and reuse and reuse...) and they are a heck of a lot easier to get out than nuts and bolts. Usually I just turn the tank upside down and they all come out. Since you are going to have to have the inside of the tank coated, take it to a radiator shop and have them put a redliner in the tank. Works 100 times better than kreem and por15. 

as for the tank, figure out what thread the petcock has and just get a single outlet petcock. I think the 75-76 petcocks will screw on to an earlier tank. Your 78 petcock might even work (there are onyl really two petcock sizes). As for different sides just run a longer fuel line. 

[kghost]

MEK is not an acid.

[78_SaltLick]

So i need to buy some marine kleen? And what else? Or does it come in a package?


Is there a tank out there that cannot be cleaned? I mean, when is too much rust, too much that is will be impossible to clean it out? This tank i got for $10, it looks good on the outside, by my god....you shake it and it sounds like there is so much dirt or something, that somone put handfulls of rocks in there. I took a flashlight and looked in there last night, and its the scarriest thing i ever saw. You cannot see even one piece of metal in there, the rust must be about half an inch thick everywhere, can this be cleaned out? I guess no one knows until i try.  

[78_SaltLick]

Can i just take this tank to a radiator shop, and ask them to clean it? I wonder how much they would charge.

[Bob Wessner]

That would be one option if you don't want to try tackling it yourself. Here are a couple of earlier threads on tank cleaning. Might be something in the FAQ's as well.

http://www.sohc4.us/forums/index.php?topic=1365.0

http://www.sohc4.us/forums/index.php?topic=2282.0

[Geeto67]

MEK is not an acid.

I stand corrected, I was thinking of Mucratic acid (sp?). We used to call it Merc acid so I thought that was what you were refferign to. Ino that I think about it we had them both at the radiator shop I used to work at but I don't remember ever using it personally, I haven't worked there in a couple of years so my memory is a little fuzzy.

One of the dangers of radiator shops working on your tanks is that if they are inexpirenced with motocycle tanks they can warp them by leaving them in the boil out for too long. I once blew up a cb450 tank that way, it was way distorted. Plus some shops will charge you $25-30 bucks to clean it. Better off trying to clean it yourself and then have them put the liner in.

[dusterdude]

take it to a radiator shop

[Tim2005]

Methyl-Ethyl-Tetone. I can't spell the damn name.

Its a medium rate evaporative solvent.

Do you mean Methyl Ethyl Ketone? That stuff's pretty nasty, I think it is banned over here nowdays as the fumes are toxic. More relevantly, it is quite explosive too, I'm just imagining part filling a tank with it, adding some nuts & bolts & shaking it all vigorously... there's got to be a chance of a little spark happening as you do that...  maybe resulting in a nice Wily E. Coyote impersonation!
  
I think the MEK is Muriatic Acid, aka dilute hydrochloric acid. Commercial rust treatments that you can buy in the UK use phosphoric acid, as recommended in those old threads too, so I'd go with that imo.

[heffay]

hey geoff... you should probably clean your tank.  granted you've by now probably sucked any of the loose stuff into your fuel filter (you do have an inline fuel filter, right?) but, getting a clean tank is always a good thing.  and, since it was most likely half filled (or half empty  ) the part that will be rusty you can't see by looking thru the hole. 
peace,
the other geoff (just call me heffay)

[78_SaltLick]

So there are places that only do radiators, and gas tanks (radiator shop) Ive never heard of a place that is advertised as a radiator shop, but then again i havent heard of much.

[frostypuck]

Most towns have a shop that specializes in the repair of auto radiators. Mine even has a logo that says "Best Place in Town to Take a Leak"
If your tank is as bad inside as it sounds, I imagine it'll leak like a sieve when (if?) you get all the rust out. Probably the reason the guy sold it to you for $10.
You can buy phosphoric acid at some farm supply places, that will take care of your rust problem. Neither POR-15 nor Kreem will fully plug all the holes that may be left behind.
Good luck,
Chris in Boston

[kghost]

I didn't advocate shaking nuts and bolts around in MEK.

Thats a bad idea.

What the solvent (MEK) will do is get out all the varnish/Congealed mess.