ORIGINAL: bgfireman
I have a OS 70 fl. It is giving me a little trouble. It has a great idle, and the high speed needle seems about right on the ground. When it is in the air however the top rpms sound like they go and come. I am wondering if air is getting in around the high speed needle and leaning it out in the air. It is on a 40 size stick. When it runs right is great fun, but you know when it does not well its not fun. In the past I have seen some people put a small piece of fuel tubing on the needle and cures a leaking problem. If this is the fix how big of a piece should be used? Anyway a little help would be greatly appreciated.
Alan
Do as directed by the first responder.
If the problem persists after following the first responder's suggestions, you may be having a problem with fuel foaming. That is - engine vibration shaking the fuel tank so hard that it is causing air bubbles to form in the fuel, which varies a great deal and which can affect how your engine runs. The simple way to check for fuel foaming is to give your gallon of fuel one or two squirts of original formula "Armor All" liquid that is meant to restore plastics. If this works, then you know that you will have to find a way to isolate your fuel tank from the engine's vibration. Also rebalance your prop.
Ed Cregger