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.

2 hours ago, Ossa said:

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.

1.  50:1 with modern oil - Castrol Power 1 is a decent oil and very clean burning

2. 1 litre capacity as clutch and gearbox share the same oil. If you're changing the oil probably 900cc as there will be some left in after draining, but there is a level plug bottom left of the clutch cover

3. No points, ignition is electronic on the MAR.  The 1977 - 79 TR77 (green tank bike) have points, they aren't strictly a MAR but are still called by that name. However, as the bikes are over 40 years old it may not have the original ignition as they are interchangeable. Can't help with gaps but I use BP7ES NGK, I think recommended is an 8

4. CR is about 10 but it may have that info in a manual

 

The frame and engine number will tell you which bike you have, they would have matched from the factory but again, in 40 years some bikes will have had engine swaps. Frame number is on the headstock, engine number by right side front engine mount, If you have an early MAR the frame number was on a sticker so may no longer be there.

You can download a manual here  https://www.custgp.com/a1manual2/Ossa 250.pdf

A lot of info here http://www.vitalemaquinas.com/

Cheers Mate I owe you a pint or 2!, I can’t wait to get out on the bike. 
regards

Steve G