OSSA

I'm helping a friend of mine to rebuild his Ossa mar we have got to the point of starting it but even though it fires up ok it refuses to rev up, we have the correct needle and jet in the Amal carb but as the throttle is opened it just seems to spit out fuel from the carb and doesn't rev up. The timing is set at approx. 3.5mm btdc and the bottom end has been rebuild by an old school motor bike engineer are we missing something obvious ? Any help would be appreciated.

Hi, does anyone know the metric screw thread for the lock nut that clamps the top yoke to the lower yoke column? I think it is metric fine or extra fine but am struggling to find a half nut for it, it definitely is not coarse. Many thanks SB

I have recently picked up a non running Tr280i that has been hand balled though a number of people of the last year or so. I was told it may have a clutch issue. After inspected it I found the clutch was completely missing. The only parts there was the hub and basket. I can buy the plates, fingers and a local shop is conforming the availability of the pressure plate and support plate. However I'm having an issue trying to find the clutch spring (number 12 in the part diagram #2420020212) does anyone happen to know where I maybe able to find one or does anyone have a bike they are parting out? I also believe my gear selector spring (number 20 in the parts di…

Ok I'm looking to replace the old amal concentric mk1 carb on the Ossa mar 350 and I've come across the Nibbi carb. Are they any good? Anybody used one?

Just purchased OSSA TR77 green frame tank etc. Looking at total rebuild and have some questions. What is the RAL number of the green? Also RAL number of the black cycle parts? I would be most grateful for any information.

Hi, last time out on the Ossa Mar it decided to pack up, after stopping, I tried to restart it but it would only kind of four stroke with the throttle wide open. Back home and the bike cooled down, it would start and run ok for a few seconds and then start four stroking and cut out. I changed the coil with a good spare one I had but still the same, when checking the spark it was very weak. So I ordered a new electronic ignition to replace the notoriously troublesome Motaplat electronic system, with the new ignition fitted the bike started first kick, the problem I have now is the bike lacks throttle responce to the point that it would be useless, on the old system it was …

Have old ossa dirt bike need to identify what year it is and what size motor it hy

Hi there I need some help ,does anyone know where I can get an Ossa tr80 350 oversize piston from,it has already got oversize B in, so looking to get the next size up,any help would be much appreciated Steve

Does anyone have an alloy tank for an Ossa mar they would sell me please

Good evening I have just aquired an Ossa with engine number M 340285 but can not find any sign of a frame number it has a white fibreglass tank and a black frame which is not showing any signs of other colours underneath it would be nice to know what model and size motor cheers

Hi I have just bought an ossa 250 mar . I have a frame number beginning B 223 and wondered if any one can date the bike for me . Many thanks

When I start my OSSA MAR the engine revs just keep on climbing until I kill engine. Carb slide working OK. Any ideas.

The rear brake on my 280i is only any good if it is wet.Any ideas why this should be?

2020 was a ‘nothing year’ and most people would like to not remember it. I found that I actually spent more money than I thought I could......... pictures to prove. Follow my gripper story #ossa_gripper on Instagram what did you spend ...

does anybody know the original thickness of the ossa mar central case gasket?....i want to know so i can get the correct -same thickness as original gasket ,in oerder to avoid shimming changes.......The old gasket seems to average at 0.025 inch ive got a new one from vintco and it mic's at 0.030 inch ...

I’m looking for a headlight reflector for my 78 VI Day. I’m not sure but I believe it was only used on the 78 black tank VI Day. I haven’t been able to find one anywhere. I’m hoping someone on this site knows of a source. Thanks

Hi I'm having the cutting out problem when at cetain temp on my ossa 280 2011 does anyone no where I could take that specialise on ossa near Manchester thanks in advance

Hi everyone , I’m hoping to get a bit more advice regarding my MAR. Over lockdown I’ve rebuilt the bike which I inherited in bits, I had never seen one in the flesh so was a bit lost initially but got some great advice here. The bike is pretty much done now, I didn’t attempt an totally accurate restoration just wanted a presentable bike I could actually use. And after some debate I decided to get the engine professionally rebuilt . Riding it round the garden it seems to run well but I have an oil leak(s) From reading other threads it seems that one of the leaks is common with other MARs in that there’s a small weep from the right side of the gear selecto…

Hi l'm having trouble tightening my clutch centre nut up to the correct torque (65lbf). Can any body suggest a method or know where I can get a suitable clutch holding tool from? I'm in the UK

Hi, has anyone had any experience beefing up the magneto cover around the clutch actuation shaft or is there another stronger magneto cover that can be used? Any help or advice much appreciated, thank you Alistair