OS55AX prop

[voitty]

Hi Guys I am trying to find a good combo of prop for this engine I have 2 planes with 55ax's and was running both with MA 13x6 K series props now the problem I am having is in the mustang running the 55 inverted runs sweet but in the Edge 540 side mounted it overheats big time and dead sticks. We tried tank heights, fuels, no cowl, carby seating, rich and lean tuning and air leaks in system and I am wondering now if this engine may be over proped even though in my mustang and my mates pulse the engine works fine with the 13x6, any other sugestions would be appreciated.

[gene6029]

Was the motor properly broken in? Has the fuel changed since breakin? I dont think the motor is over propped with the 13-6. I have 2 55AXs & am running 14-4Ws on both of them. One is on 30% heli fuel the other runs on 20% & have no overheating problems. Sounds like it may be getting lean during the flight. Try takeing off on the real rich side & see if it leans out & runs ok once its in the air. With out knowing the history of the motor more its tough to trouble shoot online. I am guessing it flips through smoothly & nothing feels tight or binding? Hope you get it figured out.....Gene

[voitty]

Hi yes the engine was broken in as per manual it had around 15 flights in the mustang before it moved into the edge540. I never had any trouble when it was in the other plane nor do i have any problems with the other 55 in the mustang which is a little newer. Same fuel 5% coolpower which i run in both engines . I did run it very rich and had succesful flights but it seemed very sluggish being rich and when i lean it out to get full rpm and back it off a little like you do it runs for 3-4 mins in the air starts pinging and dies. maybe it just needs to be super rich i dint know.

[gene6029]

Are you useing an OS#8 plug? If not, try one and see if it runs any better after richening it up like you said you did, & it ran ok for a while. The #8 plug may help keep it running while its rich & thus keep it from overheating & shutting down on you. I ran them in my helis & they puke the oil out & keep running. Cheep fix if that helps.....Gene

[rchad]

I would try a smaller prop just to see if this fixes the problem though I think a 13x6 should be fine. Are you using a fueler valve to fuel the plane? If so I would disconnect it and run the line directly to the carb. If the engine runs better then you have a bad fueler valve.

[landon]

Running a 13x4 APC on my Morris TopCat. 10% fuel(way cheaper than 30%). Flys very well. Lots of power and vertical.

[granspeed]

I have an OS61FX on a Yak which is not too different from the 55AX. It's running 13x7's or 14x4W with cowl baffle plates with air inlet holes only over the cylinder head. Engines is mounted with cylinder head on 8 O'Clock position and have no problems.

Have you checked to see if your fuel line has any kinks on the 540? Including the pick-up line inside the tank and the clunk?
How far is the tank from the engine? Maybe not getting enough exhaust pressure???

Let me know if you get it fixed because it would probably happen to me sometime too!!!

[Hemicuda]

This could be a classic sign of poor airflow over the engine. Make sure that the air outlet is 3X bigger than the inlet. You may have to restrict or block off the side opposite the engine cylinder and add internal baffles to direct the air around the cylinder and most importantly over the cyl head. Works on my Edge 540

[voitty]

Thanks for all your suggestions, I have solved the problem now and all I did was tune this plane rich until it starts going into 4 cycle tuning and then lean it out just enough to have it running and throttling up well and that did the trick no more heat problems I guess the 55's just dont like running at the leaner settings .

[wylieruneyjr]

Thats still alot of prop, try a 12x6, and the engine won,t heat-up as bad and you could possible run alittle leaner.