Dear RCV,
My RCV 91CD engine has an idle needle problem. It unscrews itself during flight making the idle blubber and quit during landings. I tune it perfectly before each flight but every time I have to re-tune it before flying again. I think the low idle needle needs a new O-RING. Since this engine is cowled AND powering a float plane makes my problem with this engine a real pain in the butt because I have to go swimming each time for one thing to retrieve my plane, then remove the cowling to adjust low needle. HELP!

Since O-RINGS are commercially available can you please advise me as to what size (ID/OD/Guage) I should purchase to replace it with? I don't think sending in the engine should be required.
Engine purchased privatley NIB on RCU in 2008.
Has less than 1 gallon ran through it.
Has hung from cieling more than flown-hangar queen.
Goldberg Cub on floats-14X6 prop.
Du-Bro anti vibe 4 cycle engine mount

I would fly it more if this problem was resolved.
First noticed idle needle anomaly 3 years ago and have been putting up with this problem for a long time. I want to fix it.