XTM Mammoth 24.7

[NitroSmoke24.7]

I have a XTM Mammoth 24.7 nitro rc truck. I bought it off my buddy for 50 bucks cause it had been sitting. It still had gas in it so i cleaned out the tank, all the lines, and carb. the motor was a bit sticky, I'm assuming from old gas turning into gel, so I took the carb off and sprayed some cleaner in the intake and crank it for a little bit and it freed up. I tried starting it and it would start for about 3 seconds and die. After a while of pulling it the pull start got very stiff so i figured i flooded it. I took out the glow plug and cleared it out, but when I put it back in it was still very hard to pull. It pulls with ease when the glow plug is out.

I think that i might have bent the connecting rod. I was wondering if it could be anything else besides that.

 

[D3MON]

is it getting hard to pull near the TDC, then it frees up? or all the way through. could be the "pinch" of the engine. (no idea how much experience with nitro you are, but the pinch is the mechanical reduction in size of the inside of the cylinder which generates the seal to give compression, nitro engines do not have rings, so use pinch instead to give it that seal.)

either way, i would really recommend tearing the engine down and inspecting. (note which rotation the piston AND sleeve are when you take them out, you can put them in backwards and it is not good to do that.
that way you can guaruntee all the debris is out of the engine. and make sure there is no scarring in the cylinder walls.

 

[NitroSmoke24.7]

is it getting hard to pull near the TDC, then it frees up? or all the way through. could be the "pinch" of the engine. (no idea how much experience with nitro you are, but the pinch is the mechanical reduction in size of the inside of the cylinder which generates the seal to give compression, nitro engines do not have rings, so use pinch instead to give it that seal.)

either way, i would really recommend tearing the engine down and inspecting. (note which rotation the piston AND sleeve are when you take them out, you can put them in backwards and it is not good to do that.
that way you can guaruntee all the debris is out of the engine. and make sure there is no scarring in the cylinder walls.

I took the engine apart this weekend and noticed the lower bushing on the connecting rod is pretty worn out and ovaled. i think it might have been getting cought up.

 

[olds97_lss]

The xtm 24.7 wasn't the best engine, but they did tune easy and had decent power. Aside from the plastic backplate, they were a decent RTR engine. If it's been run long enough to egg out the crank, it was either abused/ran lean or has a lot of time on it.

Any decent big block should be able to replace it. I know dynamite has a .28 for around $100. Not picco/novarossi quality or power, but should keep you running for 5-10 gallons if taken care of.

https://www.amainhobbies.com/dynamite-.28-rtr-nitro-engine-w-pullstart-dyne0571/p543544