Jon H Posted March 23, 2015 Share Posted March 23, 2015 You can also measure the dimensions of the bearings you removed and put that in but getting the number off the existing bearing is the beast way. I would expect the rear bearing to be a 6002 (it was on my os91) but the front will be something more obscure as its imperial and I cant remember the number. I doubt it will be necessary to replace the cam shaft bearings unless they feel nasty as well. Quote Link to comment Share on other sites More sharing options...
A.A. Barry Posted March 23, 2015 Share Posted March 23, 2015 MikeS, Hi, the bearings in the OS range are not hard to replace, but care is needed, they can be difficult to remove, I've done quite a few, getting behind them to push out is the hard bit, they have a very small ridge on the inner bearing race to push on. If ya having problems, send the whole engine to an OS dealer, for the repairs, it may save ya having to buy another Good luck Barry Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted March 23, 2015 Share Posted March 23, 2015 Isn't this just the excuse reason to get a Laser Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted March 23, 2015 Share Posted March 23, 2015 I wonder where the metal fragments in the glow plug came from? Bits of metal from bearing cages & the like are not uncommon in 2 strokes as they find their way from the crankcase to the combustion chamber via the transfer ports. This is not possible with a 4 stroke as there is no path between the crankcase & the combustion chamber. Might it be possible a small metal fragment has found its way into the carb whilst the engine has been in the workshop perhaps? This has then been drawn into the engine when it was running & caused the subsequent problems..... The 91 sounds to me like it might have partially siezed...how new was it? Another possibility might be a loose gudgeon pin circlip (if this engine uses them...I'm not sure) get one of these between the piston & liner & it will make a real mess.... I hope you get it sorted..... Quote Link to comment Share on other sites More sharing options...
MikeS Posted March 24, 2015 Author Share Posted March 24, 2015 Steve. I feared the worst when I saw a fragment on the glow plug and expected damage to the liner etc. However I wonder if the fragments made its way up the breather pipe to the carb from the cam nipple. The engine was around two years old and maybe 20 flights and it was fitted with a 13x8.5 prop. The wrist pin is held in by a white which I believe to teflon plug. Mike Edited By MikeS on 24/03/2015 07:33:03 Quote Link to comment Share on other sites More sharing options...
Jon H Posted March 24, 2015 Share Posted March 24, 2015 Posted by Frank Skilbeck on 23/03/2015 17:28:09: Isn't this just the excuse reason to get a Laser Why wait for the engine to fail? Just get one anyway! Joking aside though, it is possible for metal debris to get up past the rings into the combustion camber. Depending on what the material is it may not leave any serious marks on the liner. The breather pipe is another possibility but it would need to be quite tiny to get through the nipple. The prop you are using is a little small but its not bad, and given the model you are flying I doubt it was left flat out all the time so over revving is unlikely. Quote Link to comment Share on other sites More sharing options...
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