EGB 953 Posted April 7 Share Posted April 7 Just acquired a lovely first series Acro Wot from a gentleman who no longer flies. All looks in decent nick, except for the silencer on the OS46SF engine, which is missing the rear casing - it apparently fell off in flight some years ago. it doesn’t seem that easy to replace, in looking at the manual an OS873 silencer is specified but I don’t seem to see many of those available. are there other options? Are silencers fairly standard or do you have to go with one specified? Do all engine types have different sizes or would the silencer for a more recent OS 46 fit? Quote Link to comment Share on other sites More sharing options...
David Davis 2 Posted April 7 Share Posted April 7 Good Morning EGB! Just Engines offer a range of silencers, either standard or "quiet," which will suit your engine. In order to be sure, just measure the distance between centres of the mounting holes, dimesion "c" on the drawing. They claim that their silencers with 35mm between the bolt holes will fit an OS engine which has 35.5 mm spacing. https://www.justengines.co.uk/product-category/exhaust-systems/two-stroke-exhausts/standard-mufflers/?v=11aedd0e4327 A range of special exhausts is available to order from Weston UK. I had one made for an SC 32 and it is very impressive though they are more expensive than a standard silencer. https://www.westonuk.co.uk/Genesis-Pipes/ 1 Quote Link to comment Share on other sites More sharing options...
EGB 953 Posted April 7 Author Share Posted April 7 32 minutes ago, David Davis 2 said: Good Morning EGB! Just Engines offer a range of silencers, either standard or "quiet," which will suit your engine. In order to be sure, just measure the distance between centres of the mounting holes, dimesion "c" on the drawing. They claim that their silencers with 35mm between the bolt holes will fit an OS engine which has 35.5 mm spacing. https://www.justengines.co.uk/product-category/exhaust-systems/two-stroke-exhausts/standard-mufflers/?v=11aedd0e4327 A range of special exhausts is available to order from Weston UK. I had one made for an SC 32 and it is very impressive though they are more expensive than a standard silencer. https://www.westonuk.co.uk/Genesis-Pipes/ Good morning! thank you that is very helpful, I will measure up and get in touch with them. What are the advantages of the specialist ones? Better engine performance? Quote Link to comment Share on other sites More sharing options...
Engine Doctor Posted April 7 Share Posted April 7 Hi EGB. The weston silencers or pipes are tuned for outright performance or throttle responce and are verh good . Your os silencer mising part is likely the same size as those fitted to many chinese clones like ASP, SC etc. There are loads about secondhand have alook on ebay and check mounting hole centers. Also measure the inside diameter of the exhaust you have and you may a used end cone and through bolt on here . 1 Quote Link to comment Share on other sites More sharing options...
EGB 953 Posted April 7 Author Share Posted April 7 52 minutes ago, Engine Doctor said: Hi EGB. The weston silencers or pipes are tuned for outright performance or throttle responce and are verh good . Your os silencer mising part is likely the same size as those fitted to many chinese clones like ASP, SC etc. There are loads about secondhand have alook on ebay and check mounting hole centers. Also measure the inside diameter of the exhaust you have and you may a used end cone and through bolt on here . Thanks! Will browse this afternoon! Good to know there’s a fair bit of standardisation. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted April 7 Share Posted April 7 A common mistake with the OS style 2 stroke silencers is to assume that the rear nut secures the rear section. It’s a lock nut which should only be tightened AFTER the through bolt has been properly tightened. I suspect that this is the cause of lost silencer parts…certainly a common reason for leakage. 3 Quote Link to comment Share on other sites More sharing options...
David Davis Posted April 7 Share Posted April 7 This might be suitable for your engine. It's cheap enough but it could do with a clean. https://www.ebay.co.uk/itm/355534920581?itmmeta=01HTWSZWXSYGJ193VZ1JVBTGB2&hash=item52c7885b85:g:EDcAAOSwIvdl7xjg Quote Link to comment Share on other sites More sharing options...
EGB 953 Posted April 8 Author Share Posted April 8 13 hours ago, David Davis said: This might be suitable for your engine. It's cheap enough but it could do with a clean. https://www.ebay.co.uk/itm/355534920581?itmmeta=01HTWSZWXSYGJ193VZ1JVBTGB2&hash=item52c7885b85:g:EDcAAOSwIvdl7xjg Thanks, I measured the gap between the mounting holes and it is 37mm. As luck would have it I have found a silencer for an Irvine46 that fits nicely. 1 Quote Link to comment Share on other sites More sharing options...
David Davis Posted April 8 Share Posted April 8 I hada similar experience! I bought an OS 46 AX second hand minus the silencer but found something suitable in my box of two-stroke exhausts. I must fit the engine to the club's trainer and remove my beloved Enya 50 which is destined to go into a Calmato Alpha. Can't have such a beautifully made engine in the clumsy paws of beginners! 😏 1 Quote Link to comment Share on other sites More sharing options...
Nigel R Posted April 8 Share Posted April 8 Another on fleabay, new SC silencer that will fit. https://www.ebay.co.uk/itm/203005035517 1 Quote Link to comment Share on other sites More sharing options...
Robert Welford Posted April 8 Share Posted April 8 There is an OS silencer with 37mm centres for sale here: https://classifieds.bmfa.org/acadp_listings/os-3071-silencer Quote Link to comment Share on other sites More sharing options...
EGB 953 Posted April 8 Author Share Posted April 8 2 hours ago, Robert Welford said: There is an OS silencer with 37mm centres for sale here: https://classifieds.bmfa.org/acadp_listings/os-3071-silencer Thanks, I have sourced one already but that’s a great spot. Quote Link to comment Share on other sites More sharing options...
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