MZ 1000S tank deformation

[Dnaj11]

I've read the tank positioning thread on this forum and a bunch of stuff on the scorpion forum , so now I've come up on this problem with my 1000S. Seems the previous owner many years ago failed to replace the front bracket which holds the tank from lifting up. This caused the front edge of the tank to get all scratched from moving about near and against the headstock. So I found all the correct pieces, touched up those scratches and went to put the tank on. It appears the tank is too large for its mounting. Reading various forums, the problem arises with PA6 polymide plastic gas tanks used on MZs from the era, also Ducatis, KTM and others. They deform and swell with age and the new crappy blend of gasoline. So now I know why previous left the mounting bracket off, but that's not a good option either.

My question is this. What solutions are there? I saw where one elongated the pivot holes so the tank could fit. That may work for a while but the modification is quite obvious afterward. Has anyone tried to reshape the front bracket, or do any very minor shaping on the leading/trailing edges of the tank/headstock, find a good source for replacement tanks? Any recalls (yes I know MZ went kaput) or do anything that was less obvious. Just trying to find the most subtle option. My bike has only a few thousand miles on it and otherwise is as new.

[DAVID THOMPSON]

one place to start is pure gas

http://www.pure-gas.org

has no ethanol .. i run it in my rt125 bike runs better and i hope the tank has stopped getting bigger

yes the gas costs more but worth the money..
in the fact the bike runs better and starts better after setting for several weeks or all winter

works great in lawn mowers and boats

dave

[Dnaj11]

I read somewhere they swell up a certain amount but stop growing. Any truth to that. Bike came from Florida and down south. Methinks the warm weather makes it worse. I never leave gas in the tanks anyway. I extract it with a vacuum pump if any bike sits longer than a week. Now the bike is in the cold US North.

I did not want to slot out the holes on my 1000s frame. I remove the pivot bolts to lift the tank. I had to ream the front bracket holes a bit to make it fit. That bracket is just a flat piece of aluminum anyway. It's still a tight fit.

[DAVID THOMPSON]

where i live parkersburg wv

the weather is funny from 1973 to 1982 or so i road motorcycle year around

and even now we have excellent riding weather some times that lasts more than a week that is like summer

up till christmas then jan and feb first half of march are some times very bad ,,,

but fowl weather gear in a saddle bag are a good idea

i was in a storm just east of parkersburg wv some time in the mid 80's and it was july
with a foot of snow and ice on the ground

dec 4 2007 i was riding thats the day i had my bad wreck the weather was cool and it was just after dark
but not bad till i had the wreck then every thing was bad for awhile

dave

[Dnaj11]

Well, I don't ride my MZ1000S, its a garage queen, but have many other bikes to ride. I managed to fit the tank on well without any serious alteration. I carefully shaped the aluminum stopping plate and to remove and refit the tank, got to put out the pivot bolts to remove and install it. Its a very tight fit but at least while looking or working or ride on this bike, it remains true as it left the factory. If it was a driver or had more miles, I'd just elongate the pivot point, but I did not have to do that. My bike now has 2301 miles, I added one mile today. I'm told there only about 30 of these stateside. I've got an inquiry into Grahams about new tanks.

[daytona992]

Hi Everyone,
Interesting thread as approx two years ago I came across reports of Ducati, Bimota,Triumph, KTM, MZ and others having problems with Fuel tanks enlarging. As at that time I had five bikes with plastic tanks I did quite a bit of research. A lot is documented on the internet and everything points to the use of Ethanol added to pump fuel.
In brief: Ethanol (at present) is not added to petrol in the Isle of Man, so at least I'm safe for a while!! There is a very good web site by the Historic Vehicle Association here in the UK. Been a while since I used this site so will check its full title but basically they resent all things Ethanol. Damages many older carburetors, injectors, pumps and seals etc.
The research I found suggests many fuel tanks which are made by Acerbis are produced from Nylon 66 and apparently if subjected to water will expand. These tanks are painted on the outer (obviously) but not on the inside. Due to the effect of Ethanol being Hydroscopic water collects (as heavier than fuel) in the bottom of the tank thus causing the many problems documented about expanding fuel tanks.
Further to the many warranty claims Triumph and Ducati have reintroduced steel fuel tanks (an all round better quality item in my opinion). BMW's with plastic tanks, which I have two do not seem as affected, so I read.
No doubt many of you will have more in-depth knowledge but as I say in brief and it is an interesting topic.
Regards,
Gary.

[MJ310]

I have to buy another new battery as it hasn't got enough grunt to start, tried to lift the tank to see if there is enough space to fit a bigger battery and it seems the tank has expanded a little more since last time, just lifted a bit of paint on its nose clearing the headstock stem last time but I had to remove one of the pivot bolts this time. Any info on how to stop this would be great.

[daytona992]

Hi MJ310,
As per previous post your tank is expanding most likely due to Ethanol. Research Ethanol and its affects and plenty of info is available especially from the USA. For what its worth In the UK avoid supermarket fuel and Premium unleaded. Use Super only. Confusingly, the amount of Ethanol added to UK mainland pump fuel varies from county to county. This depends which make/refinery supply your locality. At present its meant to be no more than 5% but is especially prevalent in the supermarket and Premium varieties.
Adding Ethanol is completed just prior to delivery for no other reason than its ability to absorb water. Adding ethanol requires expensive facilities hence no-mark areas like the Isle of Man are not included which ironically is great for the vast majority of vehicle users, ie the tank on my 1000s is exactly the same size as when I purchased it new 2008.
Cheers,
Gary.

[MJ310]

Thanks Gary
I am trying to find out if it's reversable, but my first priority is to fit a battery man enough to start it.
If I find an solution I will post it.