OS 46las problems ???

[scott bolton]

 Hello Men,I have a new 46las engine. I had it reworked slightly,Hemi head,Direct NVA into venturi "supertiger" nva. The problem i'm having is twofold one it can be very hard to start because it floods very easy & it also only wants to run and hold a good stunt run on muffler pressure. It will not operate on a good 4-2 break on uniflow wheather in a plane or on my test stand. Also to make matters worse the other afternoon on my 3rd flight & 3/4 through the pattern it shut off just like a light switch while inverted and destroyed my arf nobler. This is the first OS engine i've gotten and have heard lots of great things about them. If anyone has any ideas on what might be happening please fire away.  FYI glowplug was good,2.5oz fuel left & clean NVA not sure on this one boys???  THANKS FELLAS !!! SCOTT

[Paul Taylor]

Hey Scott,
I am true blue fan, but far from an expert on engines. I can tell you what I know about them, and it will only take a second.


As for starting them, I learned the best way from Chris Sterner. I call it the Sterner Start.

Put your thumb over the vent and "pull" the prop over 3 times, remove your thumb and flip three times. Now put the glow stick on and flip hard. It should fire right up. At least it works for me.

As for the 4-2 break. Not sure you really need this engine to break. The best advice I got was set it at 10200 RPM and let it go with a 11.5x4.5 APC prop. And I do run it on muffler pressure.

I have one that is box stock on my son's Tutor 2. Did not change a thing and this engine is the best running of the 3 that we have. I have one on my Tutor 2 and one on a Scratched built Cardinal. The other two can be a little harder to start but I still use muffler pressure on a clunk tank. Set it and forget it.
Hope this helps.
Paul

[Garf]

Quitting cold is either the wrong plug, or too much oil in the fuel. I just had my OS S35 do that. The plug had gone bad.

[Jim Pollock]

Use a hotter plug until the engine is well broken in!

The best plug ever for an OS was a Champion.  Too bad they don't make them any more.  A Thunderbolt idle bar plug will suffice these days.

Jim Pollock   

[Wynn Robins]

first off - you shouldn't modify the OS LA engines - they are one of the best engines straight out of the box that you can buy..... save changing the remote needle valve ......however - if you but the OS needle that suits the front mount - you will have no issues either.

The LAs LOVE muffler pressure and run best when set up this way.  they DO NOT 4-2 Break EVER!!!!!!!  run them in a wet 2 cycle on muffler pressure - HOT glow plug (I use 4 stroke plugs), plastic clunk tank (single sintered brass clunk) 5% nitro, 20% oil (15% Synthetic, 5% castor)

I never understand why people modify these engines - they are bullet proof and fool proof straight out of the box!!!

[Steve Helmick]

What glowplug, fuel and prop? Does it still have the cheezewhiz backplate? Who modified it...and WHY?

I have run one quite a lot. Other than an aluminum backplate, .272"-.285"  venturi, PA spraybar, and PA Tube Muffler (for weight, plus the .46 muffler is on my Magnum XLS .36..also for weight!) , with 11.5 x 4 APC, T-Bolt idle bar and Powermaster 10-22, launching at 9,600rpm...it's stock. Runs great. With muffler pressure. Ran fine without it, too.

If it's got 10 runs or flights on it, it should be ok...I flew mine on the 2nd tankful. I think you've got a leak. That plastic backplate can do that, but the one I saw quit in about 3 laps, every flight. The metal backplate fixed it. Your fuel could have too much oil, but I doubt it. The first gallon through mine was 10-29 all castor, and it never missed a stroke. It could be the glowplug, esp. if it's a Fox. I've been witness to a lot of magical improvements when those were removed!  Steve

[Scott B. Riese]

OK just two cents.
The LA-46 is ready right out of the box. NO rework is need. There are mods you can do but only reach a one way run...hard 4 stroke. That's good.
OH the engine does a good 4-2-4. If you need.
The engine likes 10% nitro GMA 10-22 with 2-4 oz of castor added.
HOT PLUG
Good prop...11x5 zinger is a good starting point at 9800 no pressure.
OR 11.5x4 and run it at 10200. This engine likes this RPM'S even with pressure.
.156 spray bar .272-.280 venturi.
One head gasket.
NOW the biggest problem the tank. YOU have to have a good tank...one that works.

Scott....we need some more info. What plane? Tank? Up right engine? Prop? Rpm's? Glow Plug? Fuel?
WE all can help....


 I had one in my VEGAS at 65 oz Worked well.

[Paul Taylor]

If is ani't broke don't fix it.
I would only change the back plate if the engine has been crashed hard. You have to watch how tight you turn the screws also on the back plate. If you over tighten them you could cause a crack / leak. If you think you have a air leak and you know the tank and fuel lines are good then swap out the back plate.
RPM's are between 9800-10200 depending on the plane and prop.
And yes forgot to say sounds like you need a hotter plug. There is a chart floating around on the web I thing about plugs and hottness.

Here is Ryan's Tutor 2. Box Stock LA 46 Blue. it is like a swiss watch. And most Tutor 2's need a little nose weight so the stock muffler worked out great.

[john e. holliday]

A little silicone glue around the plastic back cured my problems with all the LA's I run,  .25, .40 & .46.  DOC Holliday

[Bob Reeves]

Wrong compression can also make them shut off like a light switch.. Might be the hemi head lowered the compression too much. When my ST 51 was doing this lowering the oil from 22 to 20% fixed it but it's a stock engine.

[scott bolton]

 Well men just a note of THANKS for all the great information on my LA46.Ater some monday morning quarterbacking & some more testing on my engine stand I do believe I may have had a glow plug fail. The plug that was in the motor at the scene of the crash was the original OS short glow plug.It is very possible that was what caused the problem. I also found out last night if i gave it two choke flips & two free flips that baby would fire up on just one or two flips of the prop.I do plan on making a quick purchase of some thunderbolt RC glow plugs and putting it in another plane ASAP! Once again THANKS for all the information & HELP!!! What a GREAT tool this site & forum has grown to be.  THANKS, Scott Bolton  Inverted=down is up & up is down !!!!

[Matt Colan]

Was it too lean the flight before?  On my OS 35S, I had a lean run, so I richened it up too much, and I just did shallow wingovers and the thing just quit.  Changed plugs and everything was fine.  what fuel are you running?  Too much oil can bog down a motor and it can quit.

[Mark Scarborough]

I must interject the prop that has resolved a LOT of the run issues Pat and I had with the LA 46, ( ok so they werent all that dramatic of issues,, ) The APC 12.25 x 3.75 prop is a really solid performer on this engine. No reduced diameter, no changing nothing, just bolt it on, use 10-22 powermaster, .272 -.275 venturi, supertiger sized needle assembly, thunderbolt plug, ( i dont use the idle bar plug) 9800rpm

[Clayton Berry]

I must interject the prop that has resolved a LOT of the run issues Pat and I had with the LA 46, ( ok so they werent all that dramatic of issues,, ) The APC 12.25 x 3.75 prop is a really solid performer on this engine. No reduced diameter, no changing nothing, just bolt it on, use 10-22 powermaster, .272 -.275 venturi, supertiger sized needle assembly, thunderbolt plug, ( i dont use the idle bar plug) 9800rpm

I love mine.  APC 12.25 x 3.75 prop.  2-4 break.  Uniflow, no pressure.  Tongue muffler.  Fox idle bar plug.  A very long venturi that I actually made on Hal Howard's lathe (three hours maybe - no idea what the ID is) and an ST NVA.  Never had the head off.  Brodak 22% 50/50 10% fuel.  On a Cardinal, on a slightly oversize Twister, and now on a biplane based on a 38 Special set of plans (it's an SE5 now).  Actually, am using a 12/5 wooden prop (don't recall the brand, and it's outside right now - perhaps a Rev-Up) on the SE5.  I choke it, make it bump, and one flip.  Usually.  A great engine.

The Cardinal just got heavy from soaking up oil (41.7 to about 48).  All monokote.  Stuff leaks.  Started with a Tower 40, but the LA46 made more power.

The Twister lookalike probably didn't need the power, but I just like the engine/prop.

The biplane needs the power.  Tower 40 wasn't working out.  But, it does alright.  Still trimming the diameter by grinding it on the pavement on take off.

My two cents.  With tax, that'll be about $145 dollars.

[Scott B. Riese]

Hey Guy's...ain't if fun to get an engine right out of the box and have a user friendly engine! Good power...fits a lot of planes. And less then $70. So kewl.   

[Gene O'Keefe]

Right on Scott - box stock except for aluminum backplate - Sig champion fuel - ONE flip starts and really does a perfect 4-2-4 break - I wouldn't run it in a fast 2 cycle - one of the best running engines I own - it really loves the
APC 12.25X3.75 prop.