David Ovenden Posted October 30, 2022 Share Posted October 30, 2022 (edited) A question to those of you with a Saito 125. Does it have a spring in the carb to push the throttle barrel out as it opens? Obviously there is diagonal slot in the barrel which (with retaining screw in the body) causes the barrel to move in and out and controls the mid/low mixture. But should it have a spring too. My Saito 115 has a spring. But the 125 instruction manual doesn't seem to show one; and on the Macgregor site the photo of the replacement throttle barrel for the125 doesn't show a spring, whereas the photo for the 115 does. So does anyone you know if the 125 should have a barrel spring or not? Edited October 30, 2022 by David Ovenden photo added Quote Link to comment Share on other sites More sharing options...
John Stainforth Posted October 30, 2022 Share Posted October 30, 2022 I don't think it has a spring. I have a Saito 125 out of an aeroplane at the moment, and its throttle barrel moves freely to any position and stays there, i.e., there is no indication of a spring in there. Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted October 30, 2022 Share Posted October 30, 2022 https://www.rcservis.sk/data/Texty/Navody/SAITO_FA/Manual EN FA-125a.pdf no spring,,, Quote Link to comment Share on other sites More sharing options...
David Ovenden Posted October 30, 2022 Author Share Posted October 30, 2022 (edited) Yes, I have the manual and (although the picture is a bit vague) I couldn't see a spring shown. Which begs the question, why do the saito 82, 100, 115, 120 etc all have springs but not the 125? Cost cutting? Surely not. I suppose it must work OK without one. Though mine seems to lack a bit of precision in returning to the same tickl-over rpm, which is why I was investigating the carb. Will give a clean up in the ultrasonic cleaner and retry. Edited October 30, 2022 by David Ovenden Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted October 30, 2022 Share Posted October 30, 2022 Is there enough space for a spring ?, if so put one in it can't hurt. Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted October 30, 2022 Share Posted October 30, 2022 The point of the spring isn't necessity to return the barrel to closed position, it's there to take out the play in the helical groove so that the radial position of the barrel always coincides with it's horizontal position. Quote Link to comment Share on other sites More sharing options...
David Ovenden Posted October 30, 2022 Author Share Posted October 30, 2022 Yes exactly, which is why it's surprising the 125 doesn't have a spring when other Saito engines do. And my 125 is exhibiting some lack of precision at tickover revs. It seems likely that a barrel spring would help with this. Quote Link to comment Share on other sites More sharing options...
Andy Stephenson Posted October 30, 2022 Share Posted October 30, 2022 If there isn't a spring in the carb then it's missing and there should be one in there. I have noticed that these springs can be of such light gauge wire that they can be almost invisible so it could be missed by the casual observer. I had a carb on a 2 stroke that had taken a knock and wouldn't give any kind of consistent running. The cause was a slight bend in part of the carb, it was catching barrel and not allowing the spring to do its work. Quote Link to comment Share on other sites More sharing options...
Paul De Tourtoulon Posted October 31, 2022 Share Posted October 31, 2022 I will have a look at my carbs David to see if you could use one of mine . Quote Link to comment Share on other sites More sharing options...
David Ovenden Posted October 31, 2022 Author Share Posted October 31, 2022 Thanks Paul Quote Link to comment Share on other sites More sharing options...
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