Topic: Painting Underside of Tank — Why Not?

[Plzhalpimlost]

Hi all! First post! Woo! I’m starting up my cb750 k5 build here, and will be painting the tank and side panels in a couple months (currently in the middle of a a full engine rebuild). Now, I see many people posting about how to paint a tank, both in videos and writing, and NO ONE I have found has managed a way to paint the underside? That kills me! How can you leave that bare-ish? Am I missing something?

I’m considering rigging up a blind seal puller to the fuel opening to be able to rotate the tank around on all sides while painting.

All the best,
J

[Bankerdanny]

I painted the bottom of my tank. I think that most of the videos don't show it because they bottom is not visible when installed on most tanks so they aren't doing any fancy painting. I don't think Honda even bothered with clear on the bottom of the tanks originally.

In my case, I hung the tank up by a hook at the filler opening and then painted the saddle area that wraps around the frame spine. I let that flash off then set the tank on a plastic saw horse to paint the rest of the tank, including the flat parts of the bottom, the very front section of the saddle area, and the tab the rear tank rubber slides over the the small amount of the very rear saddle that is accessible.

What you are describing should work too.

When I applied the clear later I applied it to those same parts and didn't worry about the inner most saddle part.

[BenelliSEI]

On my recent K0, I used an original Honda tank and side covers, that had been purchased new, over 40 years ago. They were still in the bags and boxes. bankerdanny is correct! No paint on the tank underside or side cover backs (maybe a bit of overspray))..... As he suggests, I always blow paint in there first, when doing my own work.

[1976cb750f836]

I do similar to bankerdany,  except I use 2 step ladders, with a 2 x 4 between, like a large tall saw horse. With tank bout Brest high, its easy to blow paint under and over it. I also get less trash, dust in the paint, the higher I hang it.

[PeWe]

If tank is bare to metal, primer is a must everywhere.  2k to cope with oil.
 I sprayed my tank , but not very much on the bottom. Mostly the visible parts when tank is on bike and looking from the ground and up.
Inside of side covers not. Only over spray.
http://forums.sohc4.net/index.php?topic=168243.msg2036962.msg#2036962

[Kelly E]

I painted the bottom of the tank first. When it was dry I masked it off and mounted it on the stand I made to paint it.

[Plzhalpimlost]

If tank is bare to metal, primer is a must everywhere.  2k to cope with oil.
 I sprayed my tank , but not very much on the bottom. Mostly the visible parts when tank is on bike and looking from the ground and up.
Inside of side covers not. Only over spray.
http://forums.sohc4.net/index.php?topic=168243.msg2036962.msg#2036962

Thanks for the reply! The bare metal is my concern. For the side panels, screw ‘em, they’re only getting paint on the front. But for the metal tank, I’d feel a whole lot better if it has 2k clear coat everywhere. I like how you hung yours “up and down”. I may do that with a really big hook reaching into the tank via the gas cap opening. Or the gas-hole, whatever you want to call it. 

[Plzhalpimlost]

In my case, I hung the tank up by a hook at the filler opening and then painted the saddle area that wraps around the frame spine. I let that flash off then set the tank on a plastic saw horse to paint the rest of the tank, including the flat parts of the bottom, the very front section of the saddle area, and the tab the rear tank rubber slides over the the small amount of the very rear saddle that is accessible.

Another great idea. I’m just not sure how much movement I want to be having while painting it + letting it flash means letting overspray on the shown-side of the tank flash too. The goal for me will be paint all sides, all at once per coat. Another reply mentioned masking off. That could be a good option, but then after masking, I’d be prepping the unmasked surface AGAIN to remove all the overspray from the underside job. Seems like there’s always a downside unless you can do the whole thing all at once.

[1976cb750f836]

I have also hung them from my 2 ladder and 2 x 4 rig. With strong stiff wire attach a 5-6 inch or so long  bolt, put inside filler, tie wire to 2 x 4, and hang. Then another wire from petcock hole to 1 of the ladders to keep the tank from moving around when spraying. With this setup, it ALL gets spray. Ive hung the sides with wire also, wraped around the post that go into the bike rubbers, i wire all 3 post to keep them from moving in the spray. House electric wire is stiff and can be used, or a 2lb roll of rebar tie wire from a hardware store is cheap and has a thousand uses .