vtnewb Posted January 14, 2009 Report Share Posted January 14, 2009 Hey guys, New to the forum, but I think you may have the expertise I need. For Christmas I bought my girlfriend a 1976 Ossa MAR with a strong running engine, but standard wear from being stuffed in a barn. At this point we've stripped the whole bike down and all that's left is an engine with a header pipe on it, and the frame around it. Question 1) Can I take the frame off without removing the cylinder? I hadn't planned on messing with the engine as it's running fantastic, and not looking forward to getting killed with price and shipping considering the dollar to the euro/pound. Question 2) How the heck do I remove this header pipe? I am only 23 and havn't yet dealt with a dirtbike older than the mid 80's, so forgive my ignorance. It has this little collar with holes drilled in it all the way around, but don't know what to do to remove it!!! I appreciate any help! Cheers! -Greg in Vermont Quote Link to comment Share on other sites More sharing options...
motovintage Posted January 14, 2009 Report Share Posted January 14, 2009 (edited) the flange on the pipe unscrews from the head, the engine should come out without removing the cyl and head, but I would recomend taking it off and inspecting the piston and cylinder, this is pretty easy stuff and go ahead and get a repair manual Edited January 14, 2009 by MotoVintage Quote Link to comment Share on other sites More sharing options...
vtnewb Posted January 14, 2009 Author Report Share Posted January 14, 2009 the flange on the pipe unscrews from the head, the engine should come out without removing the cyl and head, but I would recomend taking it off and inspecting the piston and cylinder, this is pretty easy stuff and go ahead and get a repair manual I'm sure you're right, I'm just used to doing my top ends with easily bought kits and gaskets. Thanks for the advice, gotto start somewhere! Quote Link to comment Share on other sites More sharing options...
woody Posted January 14, 2009 Report Share Posted January 14, 2009 The engine on a MAR won't come out before removing the cylinder without a huge amount of difficulty, there isn't enough room in the frame cradle to manipulate the engine into a position where it will come out with the cylinder on. If you manage it you'll be the first I've heard of and you won't do it without damaging the paint on the frame. Remove the front engine bolts, remove the rear top bolt and that will let the engine drop slightly at the front whilst pivoting on the bottom rear bolt which you need to loosen. With the engine tilted forward you can now remove the cylinder. If you don't tilt the front of the engine downwards there isn't enough height in the frame to remove it, it will just hit the top frame tube. Once the cylinder is off the engine drops out of the bottom of the frame, not lifted out from the side. To remove without tilting the engine you have to remove the two rear cylinder studs after removing the head. With those out of the way the cylinder can be tilted forward as soon as it has cleared the piston. If the engine is coming out anyway, tilting the engine forward is the easier way to remove it. Replacing is reverse of the above, engine has to go in without the cylinder, get the engine in then replace the cylinder. When removing the exhaust ring be sure to use some sort of tight fitting C spanner. If you use a hammer and drift to turn it, it can be done this way but it depends on how tight it is and should be an absolute last resort. You risk damaging the threads in the exhaust port which are very fine or the ring itself. Quote Link to comment Share on other sites More sharing options...
vtnewb Posted January 14, 2009 Author Report Share Posted January 14, 2009 Thanks Woody, excellent information. Can you tell me if the head gasket is metal, or uses O rings? I can just make myself gaskets, but if it's metal or something strange I want to source it before I crack it open. -Greg Quote Link to comment Share on other sites More sharing options...
woody Posted January 14, 2009 Report Share Posted January 14, 2009 (edited) The gasket between the head and cylinder is a metal (alloy) ring. They can be used over again, no need to replace it unless it is damaged in any way which is unlikely. Cylinder base gasket is paper, any gaskets you need and a fair amount of other stuff are available on ebay USA as well as USA Ossa specialists. See this site for links to various specialists; Mats Nyberg Ossa Site Edited January 14, 2009 by Woody Quote Link to comment Share on other sites More sharing options...
vtnewb Posted January 14, 2009 Author Report Share Posted January 14, 2009 The gasket between the head and cylinder is a metal (alloy) ring. They can be used over again, no need to replace it unless it is damaged in any way which is unlikely.Cylinder base gasket is paper, any gaskets you need and a fair amount of other stuff are available on ebay USA as well as USA Ossa specialists. See this site for links to various specialists; Mats Nyberg Ossa Site Thanks Woody, you're a lifesaver. My girl is going to locate a C spanner to get that header off and dissasemble tonight. -Greg Quote Link to comment Share on other sites More sharing options...
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