Hello all, this may be a redundant question but why does everyone hate the stock needle valves that come on the LA 25 and 46 motors? I did some searches but all I could find is the backplate which is plastic are prone to leaks. I'm on a pretty tight budget so I hate to spend $90. bucks for an engine and then have to spend another $40 or so on replacement parts. If i'm just sport flying my Flite Streak or Magician do I still need to invest in the extras.

Thanks, Rich

Hello all, this may be a redundant question but why does everyone hate the stock needle valves that come on the LA 25 and 46 motors? I did some searches but all I could find is the backplate which is plastic are prone to leaks. I'm on a pretty tight budget so I hate to spend $90. bucks for an engine and then have to spend another $40 or so on replacement parts. If i'm just sport flying my Flite Streak or Magician do I still need to invest in the extras.

Thanks, Rich

    As far as I can tell, for the 30-40 flights I have flown so far, the stock arrangement on the 25LA is just fine. The one knock I have on it is that one click is a little too big. That's not too surprising since the taper on the needle is much steeper than the old front needle. I also question the durability of the backplate in inverted crashes, it seems like it will break the first time you pancake it inverted into the ground. People tell me they leak but mine doesn't, yet, and if it does, we still have the old reliable silicone bathtub caulk.

     I am running the current 25LA ABC RN *exactly* as it comes out of the box, with NO changes at all in any way. I even used the preset needle for break-in, and it fired on the first flip at a perfect break-in setting. It runs remarkably well, and I have seen no reason to change anything. I have a thread about it here, nothing much to say, take it out of the box, bolt it in, attach 9-4 APC, flip and fly.

     Brett

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I also question the durability of the backplate in inverted crashes, it seems like it will break the first time you pancake it inverted into the ground. People tell me they leak but mine doesn't, yet, and if it does, we still have the old reliable silicone bathtub caulk.

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I would be awfully tempted to cut the needle valve assembly free of the backplate and make a bracket to mount it either to a couple of backplate lugs (like the FP 20 remote needle), to the engine mount lugs, or to the fuselage so that it is parallel to the cylinder and protected by it.  That's how my FP 20 needle is mounted.  It's basically in a position where it won't touch the ground in a crash, and it has survived innumerable inverted crashes.

Or if you fly in a way that you can have both hands free for adjusting the needle, leave it loose and hanging by the fuel tubing.

Tim is right about cutting the needle assembly off.  I broke one of mine (inverted landing) and was lucky enough that it didn't get into the backplate itself.  I made a bracket for the broken off assembly and am still flying it. 

The remote needle valve set up worked extremely well on ducted fan models. But is was sensitive to small adjustments.  I don't see any reason it wouldn't work on a Stunt model.  This is one of the those deals where it isn't harder and it isn't easier, it is just different.


Joe

I ran the .25LA awhile on a Skyray with the stock NV and backplate, and found it hard to start. I'd get fuel into the hose and venturi, and then it'd run back into the tank, and the prime would run out before it drew fuel up to the venturi again. It's not a problem if you use an electric finger, of course.

   I had the same sort of problem. What you need is the old 40VF hot-start "automatic choke" where you flip it and partially block the venturi at the same time, removing it once it goes.

A club member had a twin with two .15LA's that apparently had one bad backplate. It'd go 3 laps and quit, every flight, same engine. Swapped engines L2R, and the same engine quit in 3 laps, but after replacing all the backplates with FP units, no more problems. Run the plastic stuff if you want, but know what to look for when the evil happens.

    Is there any reason why large amounts of silicone bathub caulk wouldn't work? Its just a leak right?  Presumably after the plastic bulges out between the screws and the seal is lost. About 5 years ago I found an RC website that showed that as a cure.


     Brett