MZ/MuZ Riders

Time for a new petrol tank I think as its blown with the poison added to unleaded petrol. Anyone got/had similar troubles?

Mine has a few bubbles under the paint but I put that down to it living outside with a tank cover fitted....Can we have some pics of the affected areas please? Would one of the tank lining treatments help prevent it? I'm told they are increasing the amount of ethylene in UK petrol

Camera doesn't pick it up unfortunately. The sides are getting gentle ripples or shall I say waves. Once they've gone like that the plastic inside is well pooped and protecting now has no effect.

well, both of mine are 1994, and they have no problems with the plastic as such, despite being among the very oldest. Not repainted, either. In fact I have never heard of a tank dissolving or disintegrating.

I had the same thing happen to mine a year or so ago. I'd left the tank on its side, off the bike over winter, and 'ripples' appeared on the lower side. I refitted the tank and after a couple of months the ripples disappeared and never came back. I don't think the strength of the tank will have been affected, (or we would have heard about it), so I would leave it for a couple of months to see if the ripples go when the weather gets warmer.

Norman

So your not dead then bill?!! Sent you an email or two last year some time but no reply!!
We must have more cut backs here in the uk regards fuel maybe. The tank of mine has swollen over the three years I've had it. A bit like leaving a spare wheel in a wheel well with spilt oil but not as servere. I can level it as I paint bikes for a living as well as restoration but it'll still be on the move.

That's an interesting one Norman

So thanks to Norman wade with a sharp eye I've just bought one!!
Eric

The only evil in most modern fuels is ethanol. Fuel with 10% ethanol (as in most all the US) has been documented to swell certain nylon plastics about 5%; this is relatively permanent, and does not continue. I posted a long technical document written by some university describing this at some point, I still have it and can repost if needed.
Paint and metal frames do not, of course, so we have cracked paint and tanks that don't fit in the frame. But if you repaint your tank and bend/beat up your mounts until everything fits then the problem shouldn't get worse.

It doesn't explain the "ripples" though.


Sam

my 97 660 tank is a beast to get on and off the bike but it lived several years in texas heat
the 2002 rt125 seems to have been growing and is starting to be a chore when refitting
dave

Hi Sam was actually meaning bulges, not ripples as that's the way I describe poor workmanship on classic cars when looked downwards. Cheers Eric

Interesting - I had to make a new rear lug for the RT125 tank after removed for service as it would not (re) fit. I assumed this was standard MZ fit and finish but ethanol has proven to be one pain-in-the-a$$ for all small engines so I don't doubt its effect on plastic.

Jim

Mine blew the paint over the winter too, just random bubbles under the paint. aprilia rsv's have a plastic tanks made byacerbis and suffer with the same problem. it the ethanol that is being put in petrol now.the ethanol ishydroscopic and draws moisture through the plactic, If you burn it off on a ride out it doesn't have chance to affect the tank but if it sits then it does. It's highly corrosive as well if it gets on parts of your bike. I have been told by a mate with a aprilia that if you dry the tank out and leave it somewere warm the tank will go back to normal if its not to bad.

malachi wrote:Mine blew the paint over the winter too, just random bubbles under the paint. aprilia rsv's have a plastic tanks made byacerbis and suffer with the same problem. it the ethanol that is being put in petrol now.the ethanol ishydroscopic and draws moisture through the plactic, If you burn it off on a ride out it doesn't have chance to affect the tank but if it sits then it does. It's highly corrosive as well if it gets on parts of your bike. I have been told by a mate with a aprilia that if you dry the tank out and leave it somewere warm the tank will go back to normal if its not to bad.

That sounds interesting, drying the tank out to shrink it back althought I've just bought a spare tank on eBay which I'm still waiting for and want to experiment possibly on lining it with one of the liquid sealants. Not sure how it would key to the plastic internals. My idea it to line the new one not the old as there would be too much movement in the contraction as it dries out. Failing that time to make an identical steel or alloy tank!!

Ethonal in fuel is a killer of plastic tanks, Mine sat with a gallon a fuel in it and the paint up to the level of the fule bubbles and the tank expanded. The same happened to my Speed Triple Tank
So I had to buy 2 new tanks
Ducati and Harley having issues in Amarerica where ethanol is added at 10% where we only have 5% which is going to increse
Do not leave fuel sitting in your tank over a period of time ie winter
There is an additive you can by called ethomix which breaks down the ethanol - used in classic cars i which are also having issues