Having problems keeping an LRP .28 running.

[dj_sparky]

When I blow nitro through from the pipe tube, it starts, and as long as i keep accelerating it keeps running, but the moment I taper off the throttle, it stops, and then I have a very hard time starting it again. Even if I blow more nitro to it. I've never really managed to even get it somewhat hot, even though I've held it up and accelerated for quite some time. But I've never managed to idle it without it dying instantly.

It doesn't seem to get nitro from the tank without assistance, and even then I occasionally have a hard time starting/keeping it running. Running a medium OS glow plug ATM.

I've set it back to factory, which I've heard are extremely rich, so after I tried and failed at those settings I leaned in both the HSN and LSN. (I've tampered extremely much with these of course, but none seem to work.)

It's on an LST2 by the way, with a standard LST2 nitro tank, and there's a nitro filter on it as well (Connecting the 2 tubes from tank to engine, of course.)

Nitro does flow freely through when I blow on the tube, but what's up with this? I've tried for several days with several glow plugs. As soon as I get more tubes, I will try without the filter, but I don't think that's the cause.. It has good compression, so what is wrong?! Any ideas? Bought it used with about 1.5 gallons through it.

The reason why I don't think it's "destroyed" is because it runs fine as long as I accelerate and keep accellerating, and it has a good compression. Is it just hard to tune this engine or what?

 

[MotoGod]

Is your idle gap set correctly? Is your LSN set correctly? Is your throttle linkage set correctly? Check those things out first. You can't tune an engine that won't stay running ;-) You could always trim up your throttle (via the radio) to keep it running while you diagnose it as well.

 

[olds97_lss]

The LRP's are brutes to break-in. I've done two of them, and neither left me without blisters or torn skin between my fingers. Until you get 4-5 tanks through them, they don't idle well. Even then, until you get about 1/2-3/4 of a gallon through them they don't settle in well. Once you hit a gallon, they are pretty solid though.

For break-in, you have to lean them a bit from factory and up the idle a decent amount. I did with both of mine and between the two, the second one went much better than the first. Pesky learning curve...

 

[dj_sparky]

Yeah, it's not a idle gap issue or anything though. Tried everything stock, tried "my best guess", tried stock + 1 turn in only, etc. Problem is, once it gets somewhat hot, it doesn't want to start it seems. (After I've started and accelerated a bit.) It simply doesn't seem to get fuel to keep going is my best guess. :S

And it's a used engine -- it's been through about 1.5 gallons or less.

I'm going to have to open it up, even though the compression seems fine.

 

[MotoGod]

1 turn in is leaning it quite a bit on either needle. I would bring it back to factory settings and go 1/4-1/2 turn in on both needles then tune a bit from there and see how it does. Kick the idle up a bit so you have a fighting chance of keeping it running ;-)

Also....if this is only happening when the engine reaches operating temps....how is the pinch on it? When I first got into this hobby I fought with used engines...only to find out they had no compression left. Once they fully heated up and the sleeve expanded...the engine would cut off since there was little to no compression left when it was warm.

 

[olds97_lss]

You could also maybe try sealing it up:
https://www.rcnitrotalk.com/forum/showthread.php?t=72487&highlight=seal

Didn't realize it wasn't new.

 

[dj_sparky]

Thanks for the tips. Will have to do a full compression check. I didn't think it was a compression/sleeve problem atleast, since I could pretty much "keep" it running as long as I accelerated. But it wouldn't start again if it stopped, so perhaps it is indeed a piston/sleeve problem. Haven't gotten a chance to open up the engine yet (Can't find the right screwdriver.), but I've given up trying to "tune it" now. Must be a problem in the engine somewhere.

 

[Scrogg]

This issue could be due to a worn rod or bearings. @ 1.5 gallons the LRP is barely broken in, if it was done properly. The bearings are poor quality in these engines. New bearings make a world of difference.

 

[olds97_lss]

I should quit procrastinating and just do that myself to both of mine before they grenade on me. I probably have 4-5 gallons through one and 2-3 gallons through the other. Both on original bearings.

Any recommendations as to which brand/type for a general basher?