Hangar 9 nut Posted July 31, 2016 Share Posted July 31, 2016 I have two OS 61rf non pumped engines but they have two different size rear bearings can someone tell me why this is from the outside they look the same ! Quote Link to comment Share on other sites More sharing options...
Owdlad Posted July 31, 2016 Share Posted July 31, 2016 I would guess the larger bearing engine is a later model Edited By Owdlad on 31/07/2016 04:50:13 Quote Link to comment Share on other sites More sharing options...
Hangar 9 nut Posted July 31, 2016 Author Share Posted July 31, 2016 Thanks Owdlad could it be one is a long stroke and therefor has bigger bearing ! Quote Link to comment Share on other sites More sharing options...
Hangar 9 nut Posted August 2, 2016 Author Share Posted August 2, 2016 All sorted now new bearings on there way from Modelfixings,Owdlad I think you are right ! Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted August 2, 2016 Share Posted August 2, 2016 OS have specified some "odd" sizes in the past - it may be that they were getting difficult/expensive to source and they modified the casings to take off the shelf bearings. You are always best measuring the old ones very carefully - it's not unknown to find bearings in model engines with a mix of imperial and metric dimensions! Edited By Martin Harris on 02/08/2016 17:28:26 Quote Link to comment Share on other sites More sharing options...
Hangar 9 nut Posted August 2, 2016 Author Share Posted August 2, 2016 thanks Martin I got an OS 61rf in a model along with a spare rear bearing I then purchased another OS 61rf which needed a rear bearing so I thought I had a bearing that would suit but hey ho the new engine had a larger bearing but all sorted now sent them off to Modelfixings and the new ones aRE IN THE POST ! Quote Link to comment Share on other sites More sharing options...
Bill Michie Posted August 4, 2016 Share Posted August 4, 2016 Yep, correct; the earlier RF/SF (long-stroke) OS .61's had a smaller rear bearing, whereas the later ones had a bigger dia (I think, for a bigger dia crank as well as OD). Look closely at the engine crankcase, and the earlier ones have a more noticeable reduction in case dia at the brg position, the later ones show only a very slight reduction in diameter. Bill Quote Link to comment Share on other sites More sharing options...
Hangar 9 nut Posted August 4, 2016 Author Share Posted August 4, 2016 Received bearings today from Modelfixings and they fit like a glove cant wait to run it and tune it to my pipe! My other RF obviously has the smaller bearing.Great service from Modelfixings by the way ! Quote Link to comment Share on other sites More sharing options...
Former Member Posted August 4, 2016 Share Posted August 4, 2016 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Hangar 9 nut Posted August 4, 2016 Author Share Posted August 4, 2016 Yes Percy the wording came out wrong ! Quote Link to comment Share on other sites More sharing options...
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