Skorpion gas tank problem

[sandberg]

My Skorpion doesn't get ridden very often and recently had been giving me idle problems. It would die if I didn't keep it revved up. I thought I had fuel varnish causing the problem. I decide to put in some Stabil fuel additive along with a new tank of gas with the 10% alcohol. Now I have noticed that the tank has some waves in the sides. Might have been from leaning aginst something which I don't recall ever doing. It also has some small pimples which I can't explain. Anyone have any experience with this. Could the Stabil or alcohol caused the problem? Does anyone have a nice dark blue tank for sale? Any color will probably be ok.

[aah5]

Check out Grahams Motorcycles. They had some new tanks listed in there parts listings. I'm always careful about additives some can be very reactive to the plastic tank.

[sandberg]

I saw the site and he shows to have 2 tanks in Blue. I have not dealt with overseas purchases. I used bike in the US would be perfect or a leftover dealer here in the states.

What I am really wondering is if anyone else has had this problem in the past. Last night I emptied my tank and will put fresh gas in hoping to wash off whatever is going on in there.

[millgreen]

I have a used blue tank in NY
Bill

[sandberg]

Great. You can either send me your number or call me, Gary 770-517-0885 evenings.

[millgreen]

pm sent
Bill

[DAVID THOMPSON]

LOVE IT WHEN THOSE IN NEED -----FIND IT
DAVE

[sandberg]

After emptying my tank out for the winter, I have done some reading and have found that the Guy from Stabil was correct. The gasohol that is now in use here in the states is causing the problem. It seems that the alcohol content attacks the resins in the fibreglass causing it to melt away. The problem seems two fold since the tank loses its shape and the resin is clogging the carbs.

So now since I really don't want to have to dispose of my bike, does anyone know of a metal substitute tank for the Skorpion? The shape is so odd that it would be hard to fabricate one without any real skills at metal working. I bought that spare blue tank to use but that does not resolve problem. Any suggestions?

[DAVID THOMPSON]

i do not fill at stations that us the alcohol we still have a few that don't----

[samandkimberly]

After emptying my tank out for the winter, I have done some reading and have found that the Guy from Stabil was correct. The gasohol that is now in use here in the states is causing the problem. It seems that the alcohol content attacks the resins in the fibreglass causing it to melt away.

For starters, my Mz Skorpion tank is not fiberglass, it's plastic - specifically nylon 6, or PA-6. I'm new to the Skorpion world, but I'm nearly 100% certain that all Skorpion tanks are the same. PA6 is right on the hairy edge as far as ethanol is concerned: it tends to hold it's overall strength, but also to swell slightly and gain mass. It should not leach anything weird into your fuel - if you're having a running problem it is almost certainly a completely different issue. I'm relatively convinced that my tank has swollen over time; it barely fits into the space made for it with considerable force, and I doubt Mz made it that way. That, combined with the peeling of the paint all over the tank leads me to believe something dimensional has changed. My plan is to line the tank with one of the many liners available; for me that will probably be Kreme, though I have to check it's compatibility with PA-6.
Other companies, specifically Triumph and BMW also use PA-6, by the way, and there doesn't seem to be a widespread problem in the US, so I may be overreacting. There are relatively new versions of PA-6 made specifically for use with gasohol, but I do not think that these were available when our tanks were made. I dunno - anyone else in the US having a problem with their tanks? 10% ethanol has become the norm as of about 2007, I believe.

Sam

[Bill Jurgenson]

You are right of course; the tank has never ever been fiberglass. Like the others you mention and all the other plastic stuff n the Skorpion it was made by Acerbis in Italy.


It might be that the tank has swollen, but the problem of not fitting between steering head and tank bracket is widespread.
There are two simple reasons to start with:
-The bracket has moved forward a small bit or was not put back carefully. It can emoved fore and aft a bit when loose. At loos all three of mine can/could.
-The angle bracket behind the steering head has bent back. For reasons I haven't yet found, the seems to happen by itself. I must bend it forward periodically, especially with the green bike where I have always had to force the tank down at the back.

Of course a swelling would have the same effect, but the permanent condition would mean that the tank is continuously swelling. I have had no problems at all with the paint on any of the three bikes, red, dark metallic blue and metallic green. Some people add a shot of ethanol to the gas to keep condense water at bay. I don't and it doesn't seem to me to be very useful any more where the gas contains ethanol as a matter of course - here in Europe at least. I know a couple of riders who are using E85, i.e. gas with 15% ethanol.
I do add a shot of synthetic two-stroke oil to the tank when I fill up. At least as regularly as possible. A small plastic bottle with 50ml (1,7oz) = 3% is just right for the full tank and these are available for scooters to measure the mixture where the oil pump has been removed or was never there. Lots of very good reasons with most scooters to use mixture and remove the pump but that does not really belong here. Pertains to the Emmes, too.
Anyway, a shot of best quality synth is good for the valve guides, cylinder wall and the carburator(s). With no lead to lub the guides, this is always a good idea. Nothing new, It has always been the rule in 4-stroke racing. Can't hurt.

[samandkimberly]

That was good advice about the brackets; I checked them when you suggested mentioned this a few weeks ago and they were bent, so I straightened them. That brought the situation from "impossible to fit w/o a mallet" to "fits perfectly without the anti vibration mounts on the back".The front lower part of the tank it now nearly touching the front of the frame, so there isn't any more room to go.

Perhaps the deal is that the nylon swells, but only a certain percentage, then stops. It's also likely that Acerbis has done something to minimize or eliminate this issue: I have data on a 3,000 hour test of "regular"PA6 with E15 and E20 that shows 10%/11% increase in volume respectively; there's no way that the tank has increased that much. I'm remaking the rear bracket anyway, so I'm on the fence as to whether to do anything at all about this.

Sam

[samandkimberly]

FWIW, here is a recent, well done report on E10/20 and plastic:
.
http://tinyurl.com/e1020plastic

The report concludes that PA-6 is OK with E20 in spite of the 10% elongation, mass increase, and loss in tensile strength. This seems odd to me, but perhaps these changes are deemed normal for plastics. This test, though, represents worst case: high heat and very aggressive ethanol. Note that it specifically rejects PUR as a compatible material; most aftermarket m/c fuel line is PUR. This agrees with what I've seen with tubing I work with; in real life I work for a pneumatic tubing/fitting/component company (Festo). There aren't a lot of tubes that are clear, soft, and work well with both petrol and alcohol.

I'm getting tempted to pull a mold off my tank and make a few composite tanks now, just for grins and a little insurance.

Sam

[sandberg]

I am glad that the tank is not made of fiberglass. I guess the waves are just expansion. The problems with running the bike is at idle. I was thinking that maybe what would have been resin was blocking the idle jet. After running the bike for about 10 miles it would clear out and idle normally. I had added Stabil which I thought may have been causing the problem but that actually kept the idle problem from reoccuring. Hopefully next week I will put gas back in the tank and see how it runs. I hope to take it to Daytona for speed week.