It's official. I'm a VF500 addict.

Interesting. Keep us updated. I am still wondering what I would do in your shoes. Part of me says continue on this minimalist path and just see if it runs well while another part of me is saying take the time to do a thorough job and pull it all apart. Having another bike to ride in the meantime would probably be enough to have me lean toward the latter option.

Keep us posted you lucky &^% (kidding....sort of)

 

None that I can see with a flashlight and a dental mirror. And like I said, none in the aux. gas tank I used to drain the old gas yet, though there's still about a quart to go...

As far as the needle inject method you speak of, is this done with the carbs on the bike? if so, where on the carb body is it injected...up thru the drain nipple on the bottom? If so, that seems hard to do.

 

Good deal on the tank! Rust free is a definite plus.

Yes - carburetors on - you will need to use a small length of fuel hose from the disposable syringe to the float bowl drain nipple.

 

OK. I get it now. I thought by pushing the seafoam thru the fuel line attached to the carbs it would fill the carb, but I'm guessing it won't get to the bottom of them? If so, this method will take care of that. I'll try it today.

Open screw. Push with syringe. Close screw as fast as possible.

 

5x5, that's the ticket.

You don't need to worry about closing the screw right away as the syringe will hold the fuel while you close the screw. This will allow the fuel to raise up to a higher level inside the float bowl.

If I could suggest - please take a read over the Sea Foam label to double check that it isn't too harsh a mix for the plastic floats.

In the disposable syringe technique I mentioned the author was using Yamaha carb cleaner which I believe is non-caustic.

 

One of these fellas:

 

Yep. Did it with Seafoam earlier. Gonna let it sit for a couple days. I swapped coolant, replaced some rubber lines that were no longer rubber, checked/cleaned/gapped the plugs, battery has a full charge now, new oil & filter, and lubed the switches since they were sticking a bit. All electrical works well now.

I let the seafoam mixture sit 3 hours (I filled them thru the rubber line to the carbs with it as well) and cranked it over a bit. There's no gas line hooked up, but I thought I might help it stir it up a little inside the carbs. Oh...do I need to drain the float bowls before I try to start it when I put the aux tank on? I guess I'm wondering if having the carbs filled to the brim when starting will hurt anything.

Speaking of the gas tank, man...the inside of that tank, which I assumed to be flat, must have the craziest of dividers inside it. I must have put 12' of hose in there trying to get to the last bit of gas to siphon out. Anyone ever cut one open? There was about a pint of gas that would not come out, thru any hole, even with the petcock off. Speaking of the petcock, I took it all apart and did not see any clogs at all. So now I'm wondering why the gas wouldn't come out thru the connected hose earlier?

When starting this CA model without the gas tank on it and using an aux. tank, any idea what I need to do with the rubber hose that runs to the #1 carb? Close it off? Also, this CA tank has a hose running from a nipple on the front of the tank on the bottom (the side nearest the key when it's on the bike) to the giant evap. (?) canister that runs horizontally below the oil filter. Does this hose need to be closed off in order for it to run as well? (my 85 doesn't have this additional hose on the tank...it's a 49-stater).

One more thing...this is a shot of the underside of the tank, from the tail (seat) to the nose (key). You're looking at the underside of the tap/petcock. Anyone remember which nipple the hose that runs to the #1 carb goes to? A or B?

 

It should go to A. B is the vent.

Have you taken off the petcock filter cap there at the bottom yet? That may have gunk in it as well.

 

Yeah, I took it all apart and did not see anything at all that would clog it, or the vertical inside-the-tank filter.

Thanks for the tip on the hose routing as well. I'll mark the underside of the tank with a Sharpie tomorrow.

 

Wow! Those are some very clean JIS screws on one very clean fuel petcock. Looks brand new.

Here is a great drawing from Honda showing the working parts of the '84/'85 fuel petcock.

The fuel line connects to the front (larger) nipple - the other two nipples (one is concealed in this drawing) are for the vacuum line and the atmospheric vent for the vacuum valve.

The vacuum line goes to nipple 'A' in your photo above, 'B' is the atmospheric vent.

 

I have cut a VF500 tank open. There is no divider! Fuel remains at low sides of the tank especially at left side. That is why VF500 tanks suffer from pinholes below the petcock mounting plate level.
The only method I have found for removing almost all fuel from tank requires the tank to be removed from frame and petcock to be removed from tank.
Tank is placed standing on its back mounting tab so remaining fuel is now where the back tab is attached to tank body. I insert a battery breather tube ~15cm through the petcock hole and suck the fuel with a syringe.

 

Photo please!

 

Sorry there's no photo of the whole cut tank as this happened more than 8 years ago. Tank was then welded, primed, kreemed, leaked, forgoten for some years so that I recover from failure. Now is just sitting there primed-rusted.
There is nothing special inside the tank. Tank consists of just two stamped metal sheets welded together at the rim of the tank and under the trim of the petcock handle.

I can provide a photo of another VF500 tank -let me know if that helps- of which I gave a small cut just at lower right side discovering one more unsuccessful sealing attempt of the PO along with the well known pinholes.

I forgot I fished this photo somewhere in Internet from a VF500 to VF000 -electric- modification:

 

Thanks for the post. The photo is very informative.

Do you know what this area looks like in section? Is this a ledge on the inside?

 

Yeah, if I was in a hurry I'd go that route for sure. Right now I'm doing it as a kind of test mule to see if it works.

Any harm in starting it up with all the carbs full to the brim with Seafoam? Would you drain them first?

 

This area is what I am talking about!
On a new tank it's just pure void on the inside. As time goes by and humidity accumulates in tank's side "pockets" having no way to go out, rust develops and this is the final outcome:

 

very nice bike! what are your plans for it?

 

Something like this?