honestthomas Posted June 7, 2016 Report Share Posted June 7, 2016 Hello everyone and all. This is my first post and I'm sorry it's turned out to be a question. But I could do with a little help identifying what cc my ossa is. Now I have had a look throughout the forum for a few months now as well as the rest of the web but to no avail, so please forgive me if the info I require is on here somewhere already I've just failed to find it. It was sold as a 250 but after a quick web search I thought it to be a 310. But now after more searching and reading I'm left a little confused. This is what I know: it's a mk3 frame, with the layed down shocks. Both frame and engine have matching numbers starting with 57****, which the charts I've come across on the Internet don't cover. There is also a sticker on the head tube that says "230-TR-76" ,"SEPT-76" ,"570•077". The cylinder head is currently silver but looks as though it may have been black at some point, and doesn't have any splits or sections missing in the fins. Frame is a silvery grey, looks original. And the forks have black bottoms. Oh and the exhaust comes straight up from the port and over the head too. I know these last two points could of been altered additions. Any info or help in direction would be hugely appreciated. Thank you very much. Tommy Quote Link to comment Share on other sites More sharing options...
robbiesty175 Posted June 7, 2016 Report Share Posted June 7, 2016 Welcome! Photos always help. Just because we all enjoy looking at these old bikes... Quote Link to comment Share on other sites More sharing options...
honestthomas Posted June 7, 2016 Author Report Share Posted June 7, 2016 Hello Robbie, I'll try uploading some tomorrow. Thanks for the reply. Quote Link to comment Share on other sites More sharing options...
honestthomas Posted June 7, 2016 Author Report Share Posted June 7, 2016 Here's a couple of photos (I hope). If any more detailed pictures are required I can take them. 3 Quote Link to comment Share on other sites More sharing options...
robbiesty175 Posted June 8, 2016 Report Share Posted June 8, 2016 Might need to measure the piston, just to be sure. I sent this info to an Ossa friend of mine and perhaps he can help. Will keep you posted! Pretty Ossa, for sure! Quote Link to comment Share on other sites More sharing options...
honestthomas Posted June 8, 2016 Author Report Share Posted June 8, 2016 Yeah I think you might be right. Thanks for that pal. Quote Link to comment Share on other sites More sharing options...
woody Posted June 8, 2016 Report Share Posted June 8, 2016 (edited) It's a '76 250 Looks to be in original spec apart from the rear silencer which should be the 'torpedo' shape Edited June 8, 2016 by woody Quote Link to comment Share on other sites More sharing options...
honestthomas Posted June 8, 2016 Author Report Share Posted June 8, 2016 (edited) Ah Woody, I was hoping you'd see this. Thanks for the input. So it's a 250 then, can you shed some more light on how you know this? Edited June 8, 2016 by honestthomas Quote Link to comment Share on other sites More sharing options...
woody Posted June 8, 2016 Report Share Posted June 8, 2016 Frame number lends itself to the 76 250 - the series that begins 56**** so they could have run into the 57 too with the MK3. The Ossa frame numbers aren't as well documented as the Bultaco for example and some number runs don't appear on any listings. I had an all green bike which began 700 with matching frame / engine but there is no mention of a 700 number run on any of the lists available. Your also has the correct features for the MK3 with damper position, swingarm and forks. The early MK3 had the short front pipe and torpedo silencer but later MK3 had the longer front pipe (or maybe only on the 350 version?) with much longer back box, as seen on the green models. Not sure about your front pipe from the picture as it isn't clear whether it's original Ossa or not, so it could have originally had the longer type? My brother had a MK3 250 back in the era, it was the same as yours. All 350 trials motors had the barrell with split fins, only the 250 up to the MK3 had solid fins like yours has, the green model 250 changed to split fins Your bike looks as though it's done little competition use as the bashplate still fits both sides... 1 Quote Link to comment Share on other sites More sharing options...
honestthomas Posted June 8, 2016 Author Report Share Posted June 8, 2016 (edited) Woody. Aye I see what you're saying with the engine/frame numbers there, it makes more sense for it to be a later run out of the 250 than an early pre recorded 350. I'd seen you mention your 700 numbered green bike before in a similar post in the past. Are the frame/engine number sheets found on the Internet from Ossa factory records or from users that have recorded what they've come across do you know? And yes from your other posts actually, about rear shock mounting points on the swing arms I'd concluded it was a MK3 frame, and just because of the photos I'd seen on various sites of all other MK3 frames being a 350 I just presumed mine was one. Only the last week or so I noticed I'd not seen a 350 with the shorter exhaust or the plain fins on the head, without slits, and that some mk2's had a vertical one on one side? I thought it was a 350 but I had a funny feeling and now with more info I agree I thinks it's a 250 also. Really appreciate your help on this, like I said I was hoping you'd see the thread lol. Also yes it doesn't seem to have been ridden in anger at all, the sump guard didn't have a mark on it. The engine and frame too is scuff free, is this unusual ? Edited June 8, 2016 by honestthomas 1 Quote Link to comment Share on other sites More sharing options...
woody Posted June 9, 2016 Report Share Posted June 9, 2016 The cylinder is the definitive ID for 250 as only the 250 up to the MK3 inclusive had solid fins. All 350 had split fins. On a MAR it isn't possible to fit a 250 barrell to a 350 engine and vice versa due to different stud spacing. But that aside, your engine / frame number is also in the MK3 250 sequence range. Your bike is identical to the one my brother had. Only the MK1 and very first MK2 MARs had split outer fins on the head, the 350 and later MK2 and MK3 all have solid outer fins. The green models had a different style head with mounts for a head steady The chassis ID charts must have come from Ossa records originally but no idea who obtained them, but not all are as comprehensive as others with some missing number sequences that others have, and some sequences missing from all of them. There are still the odd few bikes out there that have had little use, even some that have never been sold or used from new if stories are to be believed, but yours definitely looks as though it's had little serious use, if any. Quote Link to comment Share on other sites More sharing options...
honestthomas Posted June 11, 2016 Author Report Share Posted June 11, 2016 Yeah I'm getting you now. Again Woody thank you very much really appreciate your input and time explaining. I really hoped you'd see the question and pass your eye over the job. Now there's a few other general questions I have, am I ok send you them direct? Can you do that on here? Nothing personal, still about the Ossa's. Quote Link to comment Share on other sites More sharing options...
stan wellback Posted June 11, 2016 Report Share Posted June 11, 2016 The front wheel, and therefore the fork legs ,are in back to front. the foot rests have been altered. you would not bother doing that to a garage queen. As for sump guard not being scratched, there is plenty of metal to polish scratches out on an OSSA guard. Quote Link to comment Share on other sites More sharing options...
honestthomas Posted June 11, 2016 Author Report Share Posted June 11, 2016 Haha Stan I hope you're right. I've done those things whilst waiting for a new carb. Quote Link to comment Share on other sites More sharing options...
woody Posted June 12, 2016 Report Share Posted June 12, 2016 You can send me a PM if you want with any questions but to be honest you're better off just putting them on the forum as there are several on here that are knowledgeable on Ossas, so you're more likely to get the answer you need than just asking one person Putting the forks in the other way around was done by some to improve the front brake action, I believe the idea behind this was that when you roll a bike backwards the brake always seems to work better than when it's going forwards, therefore if you reverse the front end so that the wheel in forward motion is now going in the same direction as it was when it went backwards in the conventional position, the brake will work better Never been convinced of this myself as the brake will seem to work better backwards as there is no weight on the front wheel therefore less resistance / force for the brake to overcome, plus the wheel is barely moving when going backwards, in comparison to the speed it will be rotating, or the forces imposed on it, when going forwards. It won't actually cause a problem fitted that way around as the axle is in-line therefore steering and handling aren't affected. The fork drain plugs though, are now at the front instead of the rear of the legs. Re: the bashplate - I'm referring to the fact that it is still what looks to be a perfect fit on the clutch side which means it hasn't been bent up in the middle, which forces the back down and away from the frame due to repeated impacts from hard use. None of the bashplates I have can be bolted up to the frame at the rear on the clutch side as the two don't meet Quote Link to comment Share on other sites More sharing options...
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