Ossa Tanks

[trident3]

Hi I have just got a SM Products Ossa tank to replace the tank on my 74 MAR. The new tank differs from the old one in several ways. It is angular on the top whereas the old tank is rounded as seen on most MAR pictures, the tank is slimmer and is vented from the filler cap instead of the seperate pipe just forward of the cap. Anyone know if the new tank is based on a different year/model ? As my bike has a Cheney frame I am not so worried about originality, but don't want to use a totally wrong tank.

Incidentally my painter deemed the old tank too difficult to re do as he said he could not get the multi layers of paint off - anyone know of a tank person who would be happy to deal with it ?

The new tank came with decals, these are a light green, I had already got a decal set for the panels, these are darker green, is this different years or supplier variation ?

[vaughan]

Hi,

When i restored my Ossa Tr a mate who is a car sprayer had no trouble getting the old pint off with industrial paint stripper he managed to fill a massive ding in the side, matched the original colour paint by a sample measured from under part of the Stickers, also my new decals were darker than the original i was told this was due to the old ones becoming lighter with age and sunlight,

You can take a look at my tank before and after on my web page, www.OSSA-restoration.piczo.com

Good luck,

Vaughan.

[trident3]

Thanks Vaughan, I think the issue is my tank is fibreglass, I see yours is alloy. My painter said strippers or blasting will adversley affect the fibreglass

[woody]

Ossa MAR was fitted with a fibreglass tank originally from the factory.

In UK the law changed around '73/74 which outlawed fibreglass fuel tanks (maybe just for road use or completely - don't know, doesn't matter anyway)

Therefore all Spanish bikes imported to UK after that had alloy fuel tanks made, Montesas had a fibreglass cover which looked like the original which fitted over an alloy tank underneath. Bults and Ossas just had alloy tanks made in Wlverhampton by Homerlite. All other countries continued with fibreglass tanks - Ossas did at least

This change in law coincided with the MK2 Ossa coming out in '74. Ossa themselves didn't change the shape of the fuel tank on the MK2 but all MK2 Ossas onwards in the UK had an alloy tank and the '74 - '78 models are what the Sammy Miller shape is based on. It is exactly the same except for the vent pipe. It is narrower than the Spanish Fibreglass tank. The last Green UK bikes had tanks which were shaped differently by the headstock.

As far as colours:-

The MK1 Ossa 250cc had a white tank with a broad green stripe accross the centre of the tank from side to side, painted, not a decal.

The MK2 and 3 250cc bikes had a new Green stripe like the one fitted to your Miller tank (although the Miller decal is the wrong shape - see later, don't know where they got the pattern...)

The new MK2/3 decals had to be re-shaped for the UK alloy tank due to it's differing shape from the original fibreglass tank. The factory stripes fitted to the fibreglass tank won't fit the alloy tank so don't buy any from abroad..... The UK stripes probably ended up a little darker than the original decals. I have an original (they are water transfers....) and they look darker compared to brochure pictures. Who knows what the original colour was, personally I'm not bothered and think a lighter green looks better than the darker.

Unfortunately, the Miller decals are not exact copies, they are shaped wrong and are too fat on the horizontal section. The green is near enough but the size is hopeless.

There are two suppliers I have seen selling MAR decal kits:-

www.classicbikedecals.co.uk/

and

Anglia Vinyl Art (not sure if they have a website - ebay seller)

I've only seen pictures of the kits, the shape is good enough but the green looks on the dark side although they may look different in reality. The green on the 350cc MAR decal kit sold by Classic Bike Decals looks closer to original

If you want to see brochure pictures of the original bikes look here, but remember these are the factory fitted tanks not the UK versions.

Gallery Photos

If your bike had the Cheney frame from new it could have had either the original fibreglass or a UK tank fitted as I'm not sure what year Cheney started making the Ossa frames.

I'm no expert in fibreglass repairs but wouldn't it be possible to bead blast most of the paint off with plastic bead which should be gentle enough to avoid ripping it to pieces and then finishing with a sander. You'd then need to seal the inside with a product whose name begins with a C but which escapes me at the moment although it has been discussed in Bultaco topics so someone will remember.

Just remember if you are able to use your original tank it would have been painted with the broad green stripe as per the MK1, if you want to put decals on it like the MK2 you will have to get them from abroad or just get them painted on.

Hope you are able to get it finished either way

[mick annick]

Steve Sell also has the decals to suit a mk2 tank. I have a set from Jeff Bungay but the badge is awful - nothing like the original 'cloverleaf' logo (I know it's a film reel, but who'd understand?) - steve's are better, though I've not seen any of the others on offer.

BTW if anyone has an alloy tank they want to sell, let me know...

Mick Annick

[feetupfun]

Stripping paint from fibreglass tanks is easy if you use an electric heat gun to heat the paint and then scrape it off with a paint scraper.

I've successfully done fibreglass Spanish trials bike fuel tanks this way. The latest was an OSSA MAR tank that had three layers of paint and lots of spray putty.

Warnings:

Make sure you have removed all the fuel fumes before you use the heat gun

Don't overheat the fibreglass (or it may catch on fire). Just heat the paint surface to about 50 degrees C - about as hot as you can stand to touch with bare hands.

[dirtmudnroost]

I got one of the SM Tanks for my MK1 and it is a very poor fit(read not even close), about an inch and a half shorter in length and rather angular not at all shaped like the MAR tank so depending on how you mount it you either have a gap between the tank and the seat or a rather large gap between the front of the tank and the steering head. The odd thing is it fits my friends RL250 like a glove and looks closer in shape to his tank than it does the MAR tank.

The reply I got from SM when I brought it to there attention was not to pleasing considering what it cost to purchase and then have shipped across the pond. I'll just have to pray that my friends RL needs a tank soon so that I can suck him into buying it.

Cheers

[old trials fanatic]

Nice to see though the hand that rocks the cradle may have changed the attitudes at SM havent.

Consistency thats what a thriving company needs

[woody]

I got one of the SM Tanks for my MK1 and it is a very poor fit(read not even close), about an inch and a half shorter in length and rather angular not at all shaped like the MAR tank so depending on how you mount it you either have a gap between the tank and the seat or a rather large gap between the front of the tank and the steering head. The odd thing is it fits my friends RL250 like a glove and looks closer in shape to his tank than it does the MAR tank.

The reply I got from SM when I brought it to there attention was not to pleasing considering what it cost to purchase and then have shipped across the pond. I'll just have to pray that my friends RL needs a tank soon so that I can suck him into buying it.

Cheers

The SM tank won't look like your MK1 tank as it is copied from the UK alloy tank - slimmer and more angular at the edges. However, it should be the same length.... that is what I'd call an inexcusable mistake to get past the proptotype stage.

They haven't sent you a Suzuki tank have they - SM used to make a replacement tank for the Beamish Suzuki RL......