Baxter,, my Hyper 50 sputters and stalls as I spool up, this has been going on since I bought my first Hyper 50 back when they were first realest,, in the past I could not get it to Idle for any length of time, many times it would stall as I walked to the flight line,, but as of right now the engine Idles fine (since I rebuilt it, new ring, new bearings), but this engine only has a total of 3 gallons run threw it including before the rebuild, but it will still sputter and stall on the spool up,, to get pass this sputter I have to raise the throttle extremely slowly, yet I never know if it will stall as I spool up,,

but too add I have had this SAME problem with both my Hyper 50s !! of course my # 2 Hyper I have tried the same mufflers, fuel, plugs,,

I have tried the 60B carb, different brand plugs & diff heat ranges, different fuel brands & diff Nitro percentages, 5 different mufflers including the MP2,,, and all kinds of tuning,, still I have the problem,,

I have not yet burned 30%, lately I have been burning Magnum 20% and I have had the best Idling results "it seams the problem was wose with 15%", once this gallon is gone I have 4 gallons of Magnum 30 waiting..

can I get a comment please ??
thanks !!
Jim

If a model engine that's been properly broken-in will not throttle-up without sputtering, it likely has the idle mixture set too rich. You may also have configuration difficulties, such as how the fuel system's set up, the type of exhaust system used, and so forth. Your best bet would be to "hook up" with another heli flyer to help debug the difficulty. Because you have two engines that have the exact, same problem, we'd look for something procedural or systemic. It would not be something with the engine, itself, other than adjustments.

well it did this sputtering with and without the Header Tank, but I have been wondering lately if it is my fuel line size, I have always used the medium size, that's about the only thing I have not changed, I never used the small size, I will try the small (I'm waiting for a new Main Shaft now so it will be a few day before I can try again),

thanks for your time !!!
Jim