Problem with current gasoline blends?

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Jan 27, 2008
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I finally got my early 850 started on the 19th of this month - and its sitting partially torn down again.
The basketcase I bought came with a glass tank and sidecovers. I understand that 850s weren't supposed to come with glass tanks, but that's what I have.
I used a two-part epoxy gas tank sealer from caswell's and made two applications of it. Tank cured for three months while I painted it and finished assembling the bike. Within hours of putting about 1 1/2 gallons of gas in it, the sealer starting peeling off the inside of the tank and the gas turned milky-cloudy. Tank is back off, along with the carbs and head, just to make sure this didn't cause any damage to the motor.

I've seen pictures of another Norton on this site with funky black deposits on the intake runners, and saw an Interstate with a glass tank at Wes' shop with the same symptoms (dissolved tank lining (factory) black junk on intake, AND messed up slides from this same garbage. The owner knows its from the gas, as this is the only variable in his long ownership of the bike.

Anybody else experiencing 'issues' with this new ethanol blend (its pretty much the only gas available in South Florida)?

Pakistani tank is on order, along with another pint of red paint and a set of decals :x
I used POR15. Worked better than any of the resin types and leaves a nice metallic silver finish that makes the tank inside look brand new. No problems with fuel dissolving it but then we don't have the rubbish fuels you get over there......well we are paying $8.50 for a US gallon!
I'm on my third season with a caswell-lined fibreglass tank on my 750, and all is well. Perhaps our ethanol fuel blend is different from yours :?:

Wow Bill, I thought that I had a bad time but you really did. I used the Caswell two part sealer to do my fiberglass Interstate tank. After the first slosh and complete cure, it leaked gas (and ruined some paint) but after the second slosh it seems to be doing OK. I mixed the two parts just as Caswell had measured them and both times the cure time was much longer than stated by Caswell. They ended up refunding me for one batch. The previous owner on my bike had had problems with a sticking throttle due to a heavy residue on the Makuni slide.
Well, this news isn't all that good. Until now, I had heard nothing but glowing praise for Caswell. I used the Caswell kit on Chip's Dunstall tank, I sure as heck hope it wasn't a waste. I found the cure time to be almost exactly as stated in the instructions.

I don't see any alternative to "time will tell"; I don't know that there's a product which will strip the Caswell without totalling the tank.

I just left my Dunstall GP tank bare, and hope Texas gas is so much better than all the rest, that it doesn't hurt my tank.
grandpaul said:
I just left my Dunstall GP tank bare, and hope Texas gas is so much better than all the rest, that it doesn't hurt my tank.

well as steve tyler sang "dream on"

ate 2 of my tanks before i caswell'd them
So far, it hasn't affected mine at all. Either running around (about a month) or sitting (another month).
grandpaul said:
So far, it hasn't affected mine at all. Either running around (about a month) or sitting (another month).

it takes time - you'll start to notice some nice freckles in the paint -by then it to late but at least you'll know whats up
I'm currently using Bill Hirsch tank liner in my fiber glass tank and its held up great for several months now. However, I don't feel completely comfortable with it yet.
I was told that aviation gas is still leaded, and has no ethanol, because it is not approved for high altitude. So for anyone who lives near a small airport, or only drives their bike occasionaly, that might be a good option. Plus youd get some good high octane.
Don't get caught, gahi. HIGHLY illegal using leaded gas in non-aviation applications. Airport ain't likely to let you pull up and fill up, either...

A shame, because I've got an84 airhead that could use a little lead to avoid the dread valve recession for which that year's models (among others) are known.
Hello to all. Most of the additives that I have looked contain no lead but another substance instead. You can actually buy race gas at many dirt tracks but it is illegal. I opted instead for the harder exhaust valve seats for my 750 and have been told that adding a little additive once in awhile will not hurt either.
The local airport in Granby, CO is unattended. You just pull up, and swipe your card like a gas station. I guess its a pretty small one.
Hi BillT,

I want an steel Interstate tank for my 850.

Where abouts can you order a Pakastani tank?
The Pakistani tanks are Roadster model only; you'll need a Roadster seat or else you are going to have a 3" gap between the seat & tank.
I ordered my Roadster tank from Old Britts, along with a new set of decals. I also got a spare set of side cover decals, as I may go ahead and repaint them, too. I chose them because they also include a cap with the tank, and their side cover decals include the pinstripe.
Fred called me before sending the tank out, to make sure I understood that it is going to need to bodywork to make it just right. He said they look like they've been hand-hammered to get the contours, and some minor filling will be needed.

What choice do I have?
Took me a while to figure it out too

I had (and still have) the same problem on my Fastback. Ruined two pain jobs and almost had an accident due to a sticky throttle. The thing is not all gasolines are the same at the pump, here in Montreal, the worst gas to eat out a tank comes from Petro Canada, it seems their "tactrol" additive meant to clean out injectors is the culprit, Shell probably has a similar compound but Esso (Exxon in the US) is free from the dreaded stuff. I know the gas all comes from the same place for all makes, the only difference is the additives they put in, and these are not ethanol based gas, only straight unleaded with each maker's add ons.

One tank of Pet Can gas was enough to gum up my carb and bubble a brand new paint job. The carb was gummed up so bad the slide would not move at all. Unfortunately I did not know of any tank sealers at the time. These days it's almost impossible to sell a bike with a glass tank so on my next rebuild, I will probably get an aluminum replica and dispense with sealers.

UPDATE on the Pakistani tank:

I received the tank from Old Britt's on the 7th. I was pretty pleased with the finish of the product. It comes in a box with molded styrofoam around the tank, and the tank is coated in some sort of black primer, which needs to be stripped off.
Seams are a little uneven from one side to the other, but one can't see both sides of the tank, anyway. The dimples and weld cavities are pretty minor, and glazing putty pretty much took care of them. A good coat of etching primer, and she's ready for paint. I should be able to finish it off on Tuesday, after work, and get the tank back on the bike Wednesday night.
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