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Ossa Mar 1974


martin 305
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Just got me a 250 mar with a whitlock ? frame :D , not running yet but has a spark just needs the carb cleaning i think fuel smells a bit old . Does any one know how much and what gearbox oil to use and does 50-1 synthetic sound ok ? I had one of these back in 1981 and cant wait to get it going and try a couple of twinshock trials .

Any help or advice would be very welcome as i havnt got a clue about older bikes . cheers martin :hyper:

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800cc of any modern gearbox oil will be ok in the clutch

50:1 modern synthetic is fine. Castrol TTS is good as it doesn't gum up rings and exhaust with black goo

Thats great thanks for that :hyper: but where do you fill it ? i can only think its the clutch acess panel on the left as you sit on the bike :thumbup: . Got it going today drained old fuel and stripped carb and cleaned it [mikuni] is this standard on a 1974 mar . It sounds realy crisp but not set up right yet not sure how many turns out mixture or other screw?? . When i took it to bits the frame had a whitehawk sticker on it not whitlock ? someone has spent a lot of time and money on it , its been stood a while and the clutch freed up in a couple seconds!! , no rust on the wheels not even on the nipples/ ss spokes hubs are also in great nick and the brakes work great, not a trace of rust on the forks .Realy pleased with it a bargain @

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Martin,

I don't think the Mikuni is standard, would have been an IRZ or on the later models the AMAL. Mikunis are good and depending what jetting you have, about a 2 slide, 150 main and 35-40 pilot then the Airscrew should start at 1 and 3/4 out as a datum and adjust from there.

I have a few stories on rebuilding and riding them on my blog:

"The Bulldozer from Spain"

"More from the SSDT"

"Guernsey Revisted"

Good luck, great bike

Tony

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Yes it fills through the inspection plate in the clutch cover. Lie the bike over or it will go all over the floor if you fill it too quickly with the bike upright as the clutch is in the way - or just do it slowly. Clutch/gearbox share the same oil, forgot to mention that.

Whitehawk was probably Mick Whitlock's trade name but I'm guessing.

Was this the bike on ebay a few days ago? The pictures weren't too good but you could see that the rear mudguard loop was just like a Whitlock frame but it looked to have the original MAR brake pedal set up - Whitlock frames I know had their own unique brake pedal on left hand side, but I've no idea how many variants of Whitlock frames there were for Ossa.

Mikuni isn't standard so I can't help you on set up/jetting as there is no standard setting for that carb - standard carb was an Amal. Mikuni is better so if someone has done a decent job with the jetting and it runs ok with that leave it on.

Sounds like you have a decent bike for a good price. They are a nice bike.

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Yes it fills through the inspection plate in the clutch cover. Lie the bike over or it will go all over the floor if you fill it too quickly with the bike upright as the clutch is in the way - or just do it slowly. Clutch/gearbox share the same oil, forgot to mention that.

Whitehawk was probably Mick Whitlock's trade name but I'm guessing.

Was this the bike on ebay a few days ago? The pictures weren't too good but you could see that the rear mudguard loop was just like a Whitlock frame but it looked to have the original MAR brake pedal set up - Whitlock frames I know had their own unique brake pedal on left hand side, but I've no idea how many variants of Whitlock frames there were for Ossa.

Mikuni isn't standard so I can't help you on set up/jetting as there is no standard setting for that carb - standard carb was an Amal. Mikuni is better so if someone has done a decent job with the jetting and it runs ok with that leave it on.

Sounds like you have a decent bike for a good price. They are a nice bike.

Hi woody yes it is the bike from e bay , rear loop looks as though its been shortend at some time ,the brake has been moved to the right which is handy cos i am used to my gasser .Forgot to mention it also had a new pair of betor shocks fitted !!! I will post some pics if i can figure out how to post em. Oil change and sort the carb settings in the morning :D Thanks for the advice martin :hyper:
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Martin,

I don't think the Mikuni is standard, would have been an IRZ or on the later models the AMAL. Mikunis are good and depending what jetting you have, about a 2 slide, 150 main and 35-40 pilot then the Airscrew should start at 1 and 3/4 out as a datum and adjust from there.

I have a few stories on rebuilding and riding them on my blog:

"The Bulldozer from Spain" *** * Thanks tony not sure what size jets but looking at the bike whoever built it knew what they were doing so i will try 1.75 turns and work from there :D **** right now to visit your blog. cheers martin :hyper:

"More from the SSDT"

"Guernsey Revisted"

Good luck, great bike

Tony

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