What WAS wrong with my OS .25 LA???

I simply cannot get it to run properly.
Starts ok. Very difficult to adjust the speed. After a minute it just screams away, and then stop.
Running on 10% nitro , 20% oil 50/50 Sullivan uniflow tank.
Stock needle valve .
Have the same setup on the os .46 LA. . That one runs just great.

I heard something about cracked backplate.
Would that give these symptoms?
This started hapening a few days ago. Before that it was quite ok.

.............
Took the engine out of the airplane.
Discovered that all 4 backplate screws were loose....

I sounds like a fuel flow issue. If the engines starts, leans out, and then stops it sounds like it's running off the prime. Is your fuel tank ok? Might have some dirt stuck in the needle valve.

>This started hapening a few days ago. Before that it was
>quite ok.
>

If this is the same engine you planted in the soft ground a few days ago, better check the entire fuel system for dirt. Sure sounds like you got something in your spraybar/NVA. Next worst scenario is that something got bent in your NVA.

No that was the .46. I checked the fuel flow.
I cannot get it to run properly on the ground either. I can see the fuel flowin.
I'll try a bench run tomorrow.
Norvald Olsvold

Remove the needle valve and squirt some fuel through it backwards. If there is anything in it, that should clean it out. Then check the spray bar for dirt. Just a small speck can mess things up. But the back plate can work loose and cause the same problem. Check that the bolts are tight and that they are not digging into the plastic plate. I am not a fan of these and recommend that you replace the back plate with a metal one from a 20/25 FP or 25 Thunder Tiger.

>.............
>Took the engine out of the airplane.
>Discovered that all 4 backplate screws were loose....
>
>
>Norvald Olsvold

OK, now comes the next problem. On the plast back plate it is so easy for the screws to dig into the back plate. It may not even be that the back plate came loose, but that the screws dug in in the first place. If this is so, when you tighten them, the screws will go in deeper. They can work themselves loose again (digging deeper) and you end up tightening again until the screws bottom out and you end up stripping them out of the case. I have seen this happen. Another reason I recommend your getting the metal back plate.

Can you ship me one Leonard.
I'll send the money the usual way...
Norvald Olsvold

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to get over it.

If you can't get a metal backplate then put washers and lockwashers on the screws for the backplate, it looks bad but it won't eat your holes out. Don't use locktite, it's useless if vibration works the backplate holes bigger. Dennis

A major symtom of not being able to needle is a bad or cold plug.
What glow plug are you using. I recommend the Standard Thunderbolt Long for this engine.