1984 KZ 700 fuel tank rust problem

So I bought this KZ 700 that seemed in pretty good shape a few months ago, and I've been slowly fixing it up as time permits.

My lastest is fuel tank rust. I cleaned the carbs out real good, and replaced the in-line fuel filter the last owner had put in. I flushed the tank a few times, but the filter is still collecting some rust.

The inside of the tank looks pretty clean, as far as I can see. The tank's been repainted, and what I thought was just an error in the paintjob, a friend thought might be rust underneath - it's only in a small corner of the bottom though.

I'm debating whether to try to fix the tank I have, or take my chances with one from eBay.

Anyone know if a 1984 KZ750 tank is the same as the 1984 KZ700?

Also, I've read about acid treatments, and BBs/nuts, to get the rust out before sealing. Any suggestions or thoughts, product endorsements, or warnings? I gather that it's a Bad Idea (TM) to use a tank sealer/liner if you haven't fixed the underlying rust issue first. I just moved, and I don't really have shop space in my new place, so I can't anything that can't be done on the sidewalk... is this something that a shop would do, or would they just screw me?

Thanks again for your collective wisdom.

bchoward wrote:

Anyone know if a 1984 KZ750 tank is the same as the 1984 KZ700?

Except for the paint scheme, the gas tanks of KZ750R1 (AKA 1982 GPz750) = 1983 KZ750L3 = 1984 KZ750L4 = KZ700A1

EDIT: all these tanks are becoming increasingly difficult to find, particularly in good condition. If you do find one in 'good' condition, have the seller visually document the condition as one man's 'good condition' is another man's junk.

Ask at the local radiator shop about using an acid cleaning and flush for the tank. Some guys have had shops boil out the tank.

MFolks wrote:

Ask at the local radiator shop about using an acid cleaning and flush for the tank. Some guys have had shops boil out the tank.

That is a good idea...this 'service' is not universally available...for example, there is not a radiator shop in greater Houston that will do that...yet others further north have shops that will 'boil' a tank for them.

I had to line the tank on my '78 KZ 650, too. I got the liner kit from Z1 ( www.z1enterprises.com/detail.aspx?ID=435 ) and it came with detailed instructions. You should be able to do this at your house, provided you have someplace you can set the tank outside overnight - you don't want these fumes in your house.
1. The first step is indeed to remove petcock and fuel sensor (in equipped) and then get like a piece of wood or metal that you can drill holes in to bolt to the tank and plug the holes.
2. Fill tank about 1/3 full with lightly soaped water and a large handfull of BBs or very small nuts. Put cap on. Shake tank until you think it's enough, then shake it that long again, making sure the BBs hit all surfaces, including the 'top'.
3. remove one of the plugs & the cap - drain soapy water and BBs. Flush tank thoroughly until there is no more soap coming out.
4. follow further instructions provided with the tank liner kit

This worked extremely well for me. I have no worries about debris in my tank any more, and I highly recommend it for any tank that has surface rust inside it (evidenced by brown junk in fuel filter)
Good luck!
-Al

I have done the liner kit with good results as well. Maybe you could just clean it out real good without using a liner kit. Some guys on KZR have put the BB's in the tank and sealed it up real good then put it in the clothes dryer and pack towels around it to keep it from banging against the drum. And of course use the NO HEAT setting.

If you bring it to a radiator shop to have it boiled i think you paint will be history.

Good luck!