RE: OS FP/LA -.15 Carb
I've flown a lot ofFP engines, and they all "slobber" fuel out from somewhere. And as far as longevity Ihave one I've been running since 1992I've taken it apart twice to degum it. It doesn't feel like it has much compression anymore, yet it runs; and it's black from all of the fuel that sprays out of the front bushing and carbuerator.
One of the places a lot of the fuel comes from is the venturi. I think that because the carb is an airbleed style, and not fuel meteringexcess fuel actually getsblownor drawnout of the carb and sprays all over the engine. The fp .40's and .25's that I have all do it, you can feel it (and see it) on your hands if you put your hand just behind the engine. I've oftenwondered if an extension on thecarb intake would fix that? Someday I'lltry it.
They also drool a little bit out the front of the crank case because of the plain bushing, that keeps it lubricated, it's not the same as having a bearing up front. If it runs, run it. My .15 is basically the same as the FP, but it's an OS Max, it's so old it has a strap on muffler! Still runs, although I admit it doesn't have nearly the amount of flight time my old .40fp has. And another complaint I often hear is they don't transition well, or are hard to adjust, that just hasn't been so for me. If you adjust the air bleed properly they will idle all day, and transition right up to full throttle. Most of them Idle a little rich from the factory, and will load up or flood if left to idle a lot. I'll be the first to admit though that they are not as powerful as an equal sized BB engine. They are not designed to be; the carb is smaller, the timing is different, no ball bearings. But, they are lighter than most equal sized engines, the .40fp, for instance, works nicely on a plane that calls for a .25. It weighs less than some .25 size BB. engines and will swing a 9X7 prop if you want to go fast ( have this setup on a .25 sized extra 300L...waiting for repair!) or an 11X5 on a plane under 4.5 pounds will go straight up as long as you want to climb.
can you tell I like .fp's? I've never had to replace a rusty bearing in my 20 year old .40fp, I can't say that about my YS or Saito that I've had for just about that same amount of time. I buy them up cheap at swap meets.
Austin