EB3 Posted March 12, 2020 Report Share Posted March 12, 2020 We're doing the annual on my Aerotrek A240 which has a 912 ULS. My mechanic noticed that the springs usually attached to the outside of the dual carbs are missing. I think these springs dampen vibration. I'm not sure how to order them since I don't know what they are. I can't find any info (maybe it's because I don't know what they're called). Attached is a photo from the web with the spring in question circled in red. Anyone? Quote Link to comment Share on other sites More sharing options...
BravoFoxtrot Posted March 12, 2020 Report Share Posted March 12, 2020 P/N 838-242, $13.50 each. Simply called "Spring". Should be able to get anywhere they sell parts. I have a friend with an AeroTrek and he doesn't have those springs on his either. Quote Link to comment Share on other sites More sharing options...
FastEddieB Posted March 13, 2020 Report Share Posted March 13, 2020 Speculating here... ...my assumption has been that those springs are there to keep the carbs from blowing out of their “spigots” in the event of a backfire. 1) What we usually call a backfire is more properly called an afterfire. A backfire is when the burning occurs in the intake, not in the exhaust. 2) I had a Yamaha V-twin that on a couple of occasions backfired in a way to unseat the carb on that cylinder. Anyway, that’s my guess. If anyone knows differently, I’m all ears. Quote Link to comment Share on other sites More sharing options...
Tom Baker Posted March 13, 2020 Report Share Posted March 13, 2020 It was my understanding that the intended purpose was support of the carb sockets. In the early days of the 912 I think they had some socket failures. Quote Link to comment Share on other sites More sharing options...
EB3 Posted March 13, 2020 Author Report Share Posted March 13, 2020 Thanks for the info, everyone! Maybe they weren't there in the fist place. The 912 iS in my CTLSi doesn't have them, either. Quote Link to comment Share on other sites More sharing options...
Skunkworks85 Posted March 13, 2020 Report Share Posted March 13, 2020 It appears that the HMM shows the springs to help maintain a critical distance, this will keep the "suspension" of the carb at the proper distance, From what i gather it has to do with the carb possibly sagging(due to worn sockets/age/ect) and that would maintain float levels. Also this might be interesting: all 912 uls engines have the carb support form the factory. Quote Link to comment Share on other sites More sharing options...
Skunkworks85 Posted March 13, 2020 Report Share Posted March 13, 2020 Quote Link to comment Share on other sites More sharing options...
EB3 Posted March 13, 2020 Author Report Share Posted March 13, 2020 Great info, Skunk - thanks! Quote Link to comment Share on other sites More sharing options...
FastEddieB Posted March 14, 2020 Report Share Posted March 14, 2020 Good info SkunkWorks - thanks. Well, maybe we can say holding the carb more firmly in the spigot would also help in a backfire? Quote Link to comment Share on other sites More sharing options...
Boyceyboy Posted April 12 Report Share Posted April 12 Springs are only required if you have the heavy rotax airbox. These are designed to counter that weight to protect the intake rubbers...! Quote Link to comment Share on other sites More sharing options...
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