OzVMX Forum
Marque Remarks => Spaniards (Bultaco, Ossa, Montesa etc) => Topic started by: k2000x on May 22, 2011, 02:57:34 pm
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what yamaha rod do they use on the ossa's my mar has shit it self i could just get one from ossa world but ya might be able to find a cheapy(yammie 1) on ebay
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don't think its a common yamaha rod,there was some discussion on forum fair while back,think general concenses was the rod kit from ossa world's the G O, :P
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When I pulled my '73 SDR 250 down to repair it I was dismayed to find a stepped crankpin in it of which I made at a lot more hassle than a straight pin of course and getting some bastard to do the final grinding was hard cause most shops are too lazy to take on such a small one off. If you have to make one I used EN36 as thats a steel for final case hardening and be aware that the sizes change after it's been case hardened and you need to calculate that in, Tighe cams can give you a run down if you ask nicely :-)
The pin took some pressure to get out of the halves too, had to us a 50 ton press to split it as my normal workshop bottle jack press wouldn't budge it (not that it took 50 tons that was just the next size up press I could use).
Apparently they are well known for rattling big ends as I found out at the time and I noted they were on the small side - especially in Alrons cause the motor was tilted in the frame and all the oil ran to the side.
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don't think its a common yamaha rod,there was some discussion on forum fair while back,think general concenses was the rod kit from ossa world's the G O, :P
I found Ossa world with a google search the other night seeing as I will be in the market for a rod kit etc. Are they a reputable source?
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A Yamaha YB100 rod is used for a Phantom rod with a little bit of crank half work, not sure about the Mar, I would assume they have a different size rod to the Phantom, but could be wrong.
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a rod out of a 100cc bike in a 250 ..would it bust under the higher stress
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Never had any problems with Ossa World. Been dealing with them for a few years.
They stock the rod kits at around $145.00. (straight or stepped pin)
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i've also bought stuff off them,good to deal with,don't they list an upgraded rod now for racing,as well as the yamaha conversion?,i thought they did last time i looked?, :P
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Ossa world are good to deal with. Just don't buy there fuel taps, both the ones I got broke off in the tank with very little force. $145 seems quit reasonable for a conrod kit.
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Good to know, they are good to deal with.Thanks.
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a rod out of a 100cc bike in a 250 ..would it bust under the higher stress
It's actually bigger, the standard phantom rod is very light on, especially around the area where the rod connects to the big end. the standard rod suffers from failures in this area on a regular basis, most racers do the rod conversion.
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I'm fairly sure it was YB125 (not 100) or the older YA6 125. (YB125 superceded YA6) I have the correct part nos somewhere from a guy in NSW who used to do the conversion & probably still does. Its all been posted on here before
Stepped pin on older bikes has same big-end dia as later models I'm told. As far as I know, all Ossas used same rod, even the 350, but I could be wrong
But I'd have tho't the Ossaworld kit would be as good.
Yam conversion needs machining of the flywheels cos bigend bearing is wider than the Ossa's, which means you lose some of the flywheels' 'grip' on the big end pin. Its not a straight swap-over