My LST has been sitting on the garage floor for months and it's just been getting in my way. The last time I ran it the engine just locked up totally. I keep kicking it around to get it out of the way and I finally decided to see what's going on in that little tiny engine. I yanked the mill out, pulled the head off, pulled the head button off and... whoa. What happened in here?! Looks like maybe the glow plug exploded and the filament tore up the combustion chamber. Has anything like this happened to anybody else? The last time I ran it the engine just completely stopped; it didn't flame out or run out of fuel. I turned the engine over a few times and it finally came around but refuses to start. There aren't any visible metal shavings in there anymore but I can't imagine what else would have marked up the chamber that badly. I apologize for the poor image quality. I didn't feel like whipping out the big camera for such an impromptu photo.
Need to see inside that thing, that looks like you may have lost a bearing. BTW Nitro motors do this crap all the time.
I went ahead and bought a replacement engine altogether. The cost for a new piston, sleeve and head button was half the cost of replacing the engine. And that's assuming the crank, conrod and carb were still good. I've been through my fair share of nitro motors but never had one just completely grenade like this one. With the last engine that blew up on me (TRX 3.3 in a Revo) I literally broke the engine mounts off the case and cracked the case open. I was actually a little proud I could do that much damage
seems like it might be kind of a stretch for a bearing to make its way all the way to the top end. and get past the piston. thinking maybe your assesment of the gloplug fraggin out might be more plausable nex. perhaps a portion of the cylinder let go at one of the ports? if your old cylinder still has pinch and isn't scored, here is your opportuntiy to do a little port work. if you mess it up, well at least you have a new one. anyway, good call on plunkin down the coin for a new mill. now you have some spare parts WHEN you need them, and you will eventually... Nitro, it can be a love hate relationship ;D best of luck, D
It's actually more common than you would think for bearing material or any material for that matter to make it's way to the top of the cylinder. A glow plug flint "usually" won't cause anywhere near the damage seen here.
Well, whatever the cause I've got a new engine in the LST and breaking it in. It's been so long since I've actually driven it that I'd forgotten a lot about it. When I got to the "give it 1/2 throttle for a tank" phase it started to shift into second gear and it surprised me at first. Then I remembered that it even has a high/low gear selector. It was almost like discovering new features.
It's actually more common than you would think for bearing material or any material for that matter to make it's way to the top of the cylinder. A glow plug flint "usually" won't cause anywhere near the damage seen here. [/quote] Sin, yeah, now that you mention it, and i ACTUALLY think about it with a nitro/two stroke mindset.. makes total sense. i think i was thinking kind of with my automotive mindset, (like a dumass). But yeah.. fuel, ports, hydraulic pressure from the piston coming down into the case..all makes total sense. The fuel and case pressure forces the bearing material right through the ports and into the top end.. bingo. Apologies for my ignorance. i don't have much experience with nitro honestly. (as if you couldn't already tell :-[ I got rid of mine without ever really gettin to run them much/ they were always broke down) Anyway, It looks like the piston has a some scoring right at where the port windows would be.... now it is all so clear. Sorry for being a dumbass and commenting on something i don't really know that much about. My bad.
No reason to apologize, this is all for the sake of learning and bettering our-self. No one is ever wrong, they are simply not educated yet in the field as it should be put . Believe me when it comes to anything other than ground rc, I am a complete newb. :-\
Maybe this weekend I'll pull the whole crankcase open and solve this mystery. I know the wife is tired of it sitting on the dining table...
