Ossa MAR '74

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Rod
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Ossa MAR '74

Postby Rod » Tue Jun 03, 2014 8:00 pm

As above, it arrived in the mail today, 40 yrs old and it looks good and runs well, thanks Howdy 2.

What's some improvements that can be done on the forks internally to make them work a little better ? I'm sure they're original, so 'betor' I'm thinking ?

What are these 'magicals' springs I've stumbled across on the web, do they magically transform Bultaco/ossa/montesa front ends from the 1970's ?

I have lots more questions to come regarding old Ossa's, so be prepared.

Any advice appreciated other then " Don't buy an Ossa." Cause that's too late!



David Lahey
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Re: Ossa MAR '74

Postby David Lahey » Tue Jun 03, 2014 8:50 pm

OSSA MAR forks were made for OSSA by Betor and in my opinion are the best of all the 1970s Spanish twinshock 35mm trials forks for action. If the springs are severely sagged then new springs will make them work better. There is nothing magical about magical springs. They do require longer spacers than normal springs to get the spring preload setting right unless you also buy the magicals fork caps, and if you buy the magicals fork caps, the preload can be adjusted without taking the fork caps off. No they do not transform the front end.
There are two sorts of MAR forks. The early ones have a squared off end to the slider at the axle end and the later ones have a waisted section at the axle clamps. I think the later ones have slightly more travel.
OSSA MAR fork sliders have a relatively narrow top bearing (compared with Bultaco and Montesa) which as well as minimising friction, means faster wear. If yours are worn you may have problems with seal wear rate
If the internals are working properly the damping action is very good with 10 or 15 WT fork oil. What is it that you don't like about the action of the forks?


relax, nothing is under control

Rod
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Re: Ossa MAR '74

Postby Rod » Tue Jun 03, 2014 9:37 pm

David, mine are the wasted away at the axle type.

I will be at Connondale for classic dirt, I will track you down and pick your brain, see you then. Cheers.



Rod
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Re: Ossa MAR '74

Postby Rod » Thu Jun 05, 2014 6:21 pm

Does anyone know of aftermarket footpegs that are wider then the originals ?



Rod
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Re: Ossa MAR '74

Postby Rod » Thu Jun 26, 2014 8:25 pm

What should a Nov ' 74 MAR look like ? Mine has the same thick green stripe as the original MAR, I thought it should have the thinner green/gold stripe that sweeps back to the seat. I'm not into resto at the moment but would like to know what I've got here. It still has a sticker attached to the head stem which reads from top to bottom like this: 250-TR-74, NOV-74, 222-852.

PS; I never made it to 'Classic Dirt' Connondale.



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Re: Ossa MAR '74

Postby David Lahey » Thu Jun 26, 2014 9:40 pm

Hi Rod I didn't get to CD10 either.
My memory is saying that the main things that can differentiate the Mk 1 and Mk2 (1974) MAR nowadays, after so many have been redecorated, are the cylinder barrel and the wheel rims.
The Mk2 barrel has a spigot where the carby attaches while the Mk1 has something different I can't recall
The Mk2 wheel rims are shoulderless aluminium Akront while the Mk 1 rims are shouldered aluminium Akront (mudcatchers)
MK 1 came with a moulded composite bashplate and Mk2 came with an aluminium bashplate, but the moulded ones lasted such a short time that there are not many MK 1 MARs still with them on
There was a change made to the length of the swingarm too (lengthened from the early ones), but I have not made a study of when the change was made
The Mk1 had an IRZ carby while the Mk2 came with a Mk1 AMAL concentric with spigot mount
There is a difference in the finning on the cylinders too but I can't remember which is which
Please someone correct this as I am working on memory here

If you haven't seen this magnificent website by Mats Nyberg before I can recommend it for OSSA trainspotters

http://ossa.2y.net/index.html


relax, nothing is under control

Rod
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Re: Ossa MAR '74

Postby Rod » Fri Jun 27, 2014 6:55 pm

Hadn't seen that site before, now added to my favorites list.

I've definitely got a mk2 as it has the round spigot with a mikuni fitted, shoulder-less rims, alloy bash plate, wasted bottom fork legs. So I'm thinking a previous owner just didn't like the later model striping and has painted it with the thick green stripe as per the mk1 original, I actually prefer this look myself.

It's got some other nice mods other then the mikuni like flat rear sprocket with the spacer/bearings, gonelli guards with period correct looking front stays and NJB shocks I think.
Interestly, the seat base is pressed alloy with shark teeth on the underside to secure the cover, not something made up in a backyard workshop. I thought seat bases were plastic or fibreglass? It's a beautiful looking bike and I hope to be riding it soon at the Jeff Gough Memorial Trial.

Still trying to work out what to do about the anorexic footpegs!



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Re: Ossa MAR '74

Postby David Lahey » Fri Jun 27, 2014 8:27 pm

here's what I'm bringing to Conondale in November, haven't decided which "look" yet
Attachments
OSSA June 2008 008.jpg
OSSA June 2008 002.jpg


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Rod
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Re: Ossa MAR '74

Postby Rod » Sat Jun 28, 2014 12:45 pm

Very nice, the MAR look for me. That's the stripe setup I think mine should have.



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Re: Ossa MAR '74

Postby Montesa13 » Sat Jun 28, 2014 7:15 pm

David Lahey wrote:here's what I'm bringing to Conondale in November, haven't decided which "look" yet



Wow what beautiful looking machines David!!




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