OSSA

Does anyone out there know what size flywheel puller I need to remove the flywheel on a '72 250 MAR? From what I can roughly measure, the inside diameter of the flywheel is 26mm. Not sure about the pitch.

I need to pull the magneto flywheel off on a '72 250 MAR. Probably a silly question, but which direction do I turn the flywheel nut? Clockwise or counterclockwise.

Can anyone advise if the longer fork tube for the TR80 will fit the MAR legs please, and also are the fork caps the same thread? (think the TR80 caps are different) Wanting to use on a Triumph project. Thanks

Hello everybody, could someone please tell me lengths of spokes I need front and back for a 1975 250 MAR? I know I can buy them off the shelf from in motion but don't want the expense of stainless steel . Best regards, Colin.

I am considering have the swinging arm off my TR77 powder coated and if so I thought it would be a good idea to remove the bushes and spindle. The spindle seems a really tight fit in the bushes, can anyone advise me of the best way of removing the spindle and the bushes. Thanks.

Hi Guys, I have an issue with my TR77 350 clutch is working okay select 1st gear ok pull away but while moving can not go up the gearbox, the same when I stop moving and the bike is running. when the bike is not running I can click it up the gears by hand. ??? anyone had this before or know what the issue could be, im unable to split the crankcase as do have the know-how leave that to the pro`s. Any suggestions of good engine builder who could have a look, im based in Hemel hempstead. Many thanks Rick

Is it possible to fit an electronic ignition to a 1975 Ossa 250 MAR? If so where can I get one ? Failing that has anybody got a points ignition set in good condition that I could buy? I'm based in England . TIA

Hi there, I have 2013 TR That is extremely hard to actually get kicker to move. I I have a 9 V system starts first/ second kick but 5 out of 10 starts I’m stomping on the kick start lever and still can’t get the lever to move. I can put my whole weight on and just bounce me off really worried it’s gonna break is there a reason

Yesterday I was riding at a local trial event and bike was running fine. And then I was unable to shift in second or neutral, it was stuck in 1rst gear. I didn't drop the bike or crash it on that day. This morning I removed the transmission and I can't see what's wrong. I tried to change the shifter spring adjustment position with no luck. Unlike yesterday, now with the trans out, I can move between 1rst gear and neutral. But can't go up in 2nd gear. Any idea of what can be the problem? I seached on the internet but didn't found anything similar.

As the title states, I'm looking for a particular TR250i map. The exact name of the map is "20130727_OssaTr250i_Evo2.rom" I have two ostensibly 2014 model year bikes. The early TR250i came with the EVO2 map. The later TR250i came with dual maps. I have tried all available maps and the one I prefer is EVO2. Does anyone have that map file? I have not seen anything between EVO2 and EVO6. So I'd be willing to try EVO3, 4, or 5 if they exist. Thanks in advance!

Hi all, I went for a rather long ride and both my brakes seized up. At this point, I'm focusing on the rear. I thought maybe it was the weight of the lever acting on master, making the rear brakes drag and heat up. Should there be a return spring on the rear pedal, if so where does it go? Thanks in advance!

I have a 1975 250 MAR but the rear brake has 25mm wide shoes which i think was from earlier models (?), InMotion only stock 30mm wide. I am assuming these don't fit but i can find plenty of Y503 shoes that are 110 x 25mm and cheap too for genuine EBC, has anyone tried these or am i left with finding a local relining company fr the solution? Any help gratefully received, Ian

At my first trial today which I thoroughly enjoyed,(Thanks Loughborough club) I lost a swing arm spindle bolt (Shame on me for poor preparation). But when we dug a little deeper it seems really strange that the position of the rear brake pedal is effected by the chain tensioner and by default chain tension. I'll blame this for my ineptitude to find the rear brake pedal for descents. Is this really correct. Thinking of removing original tensioner and fitting an aftermarket one to disassociate the 2, so the chain tensioner tensions and the brake pedal brakes, and I can fix its rest position in one place. Have I not got mine set up correctly, is it missing somethin…

Hello, bought a Tr280i over a year ago, unaware (didn't check!) that the parts were difficult to get hold off. Changed oil this weekend only for drain plug to shear off, managed to get it out! Can't find one on google, trials and tribulations sold out.... Anyone know if a gas gas or other bike will fit? Outside diameter is 11.6mm, but its not M12, could be BSP, NPT metric fine.....not sure, just hoping another bikes will fit thanks

Hi all, I have a 72 ossa mar mark1, in 2017 I acquired the bike, I renewed the gear oil and from that point onwards my clutch sticks,when cold and to re-release it I need to rock the bike back and forward,my question is what is the correct oil I should be using for the gearbox/clutch, thank you for your response in advance, Ed

I am restoring my Ossa Tr77 250 and would like to keep it original as far as is possible. As far as I can tell the frame still has the original finish albeit rusty in places, the Ossa silver vehicle type sticker is still on the headstock along with the stamped frame number, so I am reasonably sure it has never been repainted.The build date on the sticker is May 77 and the frame is a light grey almost metallic with the tank and side panels being the usual green. Has anyone come across this colour combination before? most bikes on the forum/internet etc from this era seem to have black or green frames. I would be interested if the light grey/green is a combination that any…

Hi, can anyone shed light on my question? Ive an Ossa 250 MAR 1976 model, I’m having trouble with starting it, it was running ok then died, on kicking over the spark looked weak, suspecting electrical failure I tested HT coil which seams ok, I stripped down and removed the stator. I’ve tested this and seams ok no open circuits. I am wondering, as the ignition is supposed to be Electronic, why are there points and a condenser fitted to the stator? Please can you help, I’ve posted a picture of the stator. regards Steve G

My OSSA MAR 250 has Harpowa (Kershan Bradford) reed valves fitted. Does any body know where I can get replacement blades (petals) for them (UK) ?

Hello ossa people, I have recently had my 125cc TRI 2013 engine all rebuild because the crankcase was all split open at the air-inlet side below the cilinder. Now I got it back with a new crankshaft in a new case. When testriding I noticed I didn't have power and I can not get the frontwheel of the ground like normaly. I was told by the store that it takes at least 10hours to losen up the new crankshaft so that my horspowers will return to normal. When opening the throttle I notice how the RPM's are slower comming up. Indeed it feels that the engine is so tight that the piston is not running lightly. Mecanicaly the gears and clutch see…

Hi just joined so you are probably fed up with the usual requests. I’ve just bought a n Ossa 250 MAR, I need basic information as there’s no manual for it. I would be grateful of any information you can provide 1 ). Petrol to 2 stroke oil ratio. 2). Gearbox oil quantity 3) spark plug and points gaps 4). What should the compression ratio be . Many thanks Steve G.