Strange XXX-NT engine problem!
 

I have an origional XXX-NT RTR truck, but the Dynamite Mach .15 engine has been running rough. It refuses to cooperate. I reset the mixture needles, played with the carb, replaced the glow plug, rebuilt the engine, checked for leaks, and done any other maitnence I can possibly think of. The carb is broken, but I didn't think it would make it not start. The barrel of the rotary carb opens as it rotates, but it also moves side to side, another way to look at it is, the servo horn on the throttle, moves in (towards the carb) and out (away from the carb). Could that be my problem? The engine only has about 1.5-2 gallons thru it. When it does run, it sucks up gas VERY quickly, and will not start unless the carb settings are at the break-in positions, which make it way too rich. Once the engine is going, I can usually tune it to make it leaner. It also doesn't stay running for very long. After I modified the XXX-NT to fit a TRX .15 EZ-START system, it starts a little easier, but still not like it should. The other thing it does that makes me wonder is that sometimes, when I plug in a 7.2V battery to the EZ-START motor, then hook on my glow ignitor, it will start in one more crank, AND RUN GREAT! But other times I take it out and try to start it, and I am using up a 7.2V battery on nothing but pops and snorts. It's weird! Anyone got any ideas?

No one got an answer for me?

after further thought...

dont know if I am the right one to answer that one...

1.5 to 2 gallons. Well since you rebuilt it, it should give you no problems. Probably a starter box would eliminate most starting issues. They are just that much better than any kind of roto start units.

That said you probably don't want to get a box, which nothing wrong with that I just mention it b/c they take care of so many problems that aren't even really problems to begin with. Ok, enough with that.

I had a dynamite motor a long long time ago. I hated that motor. Not really the motor but the carb. Even after a rebuild the thing wouldn't run for beans. I figured newer ones would be better now, but maybe you are proving that theory wrong.

My suggestion to you is to not spend another dime on the motor. Run the life outta the thing, then go buy an os motor. CV-R, TR, Tz, any of the os motors should make you fall in love with nitro all over again. They are affordable, powerful, and have great tuning carbs. Good luck to ya!!

im with jbrow1 get a starterbox then get your self a better engine like a O.S. cv/cv-r, tz.

When you rebuilt the engine did you replace the front bearing? Even on the OS engines I take them out and replace it with a rubber seal bearing. Most of the time the bearing gets worn and leaks through the front bearing. This might be your problem.

After re-reading your post it doesn't sound like you rebuilt it. Since it's around 2 gallons I'd take the motor all apart. Then see how far the piston pushes up in the sleeve. If it goes to the top it's time for a new motor.

A worn motor will run, but it hard to start and needs to have a very high idle to keep from stalling when you let off the gas.

I rebuilt it, but I didn't replace any internals. After checking all the parts, I took the conrod, crank, piston, block, and carb and set them in a pan full of water, then boiled the crap out of them. This freed a lot of grime from the inside of the block, and before long, I had a light scummy/oily residue on my pot! After I took them out, I cleaned all the outside parts, and reassembled them. I installed a new glow plug, chucked the starter, tuned the carb, and went outside. It took a while to get going, but when it did, I made sure it was tuned for break in, and ran it around at low revvs (because the thing doesn't idle long before dying). The top of the piston is clean, and everything is snug, but it doesn't seem to have as much compression as it should. I did have an O.S. engine before. It came in a used Kyosho Field Beetle I bought for $150. It obviously had several gallons through it, but it did start and run alright. The only problem I had with it was the idle. It would'nt idle very low. Mabey it's the way it was made, or mabey it was me just being used to the MACH .15, but it just idled high. I tried to turn the idle down, and played with the low speed mixture for a while, but I gave up after it kept dying. After I took the engine apart to see what shape it was in, I found that it was beat pretty bad. There were a lot of scrathces in the sleeve and piston, and the top of the piston was grimey, but it still ran alright! It wasn't long after that it started giving me trouble, which is suprising, because the piston was beat up so bad I was suprised it ran at all! Especially when my Dynamite seems to die when the wind blows! I guess I should just go for a new motor. Before I do I will probabl try a new carb. I want to see if Dynamite makes a slide carb, mabey I'll have more luck with that. If I do get a new engine, I want it to be a nice, classy Italian job. A Rossi, Novarossi, PICCO or something like that. Either that or try and see if I can stuff a TRX 2.5 in there. I might as well. Why get another $70 or $80 motor when this might happen again. The only other question I have, is what is the quality like with the Italian mills? Are they really all they are supposed to be? Thanks for all the help by the way.

Well you're describing the symtoms of a motor that has lost it's pinch. Same with the os motor you talk of. I wouldn't waste my money on a different carb.

As far as motors go, I run a novarossi mt .12 The thing is bruishly powerful, super fast and is supposed to have great engine life. I think the carb is as good as any os one I've had also, but have heard of those who have problems with them. The mt .12 isn't made any more, but there is a motor that is the same thing just called something different. I don't remember the name.

The main difference btw the high dollar motors and the 80 dollar motors is you're just out more when they lose pinch. I just built an os cv .12 to replace my nova because I only need the nova on select tracks. So I will run the cv to death on all the other tracks because I like it, it's got great usable power, and I can get new piston and sleeve for 20 bux.

That all said if your piston and sleeve is still good, google search osrocket. He'll pinch your sleeve to better than new for 20 bux or so. But still I personally am not a fan of dynamite motors and would go get an os or whatever motor you feel like getting.

I can't fit the piston totally through the sleeve yet, but there's more play than I would like. Mabey I'll just get an O.S. .12 or .15. Before I do, I'll run this one as much as possible. Like with my E-MAXX, if I got to get a new one (in the E-MAXX's case, the motors) I might as well watch the old one burn, right? Unfortunatly, the E-MAXX motor won't quit (unlike the MACH .15)! It shouldn't be that hard to destroy the Dynamite though. Thanks for the help!

The CVRX would be a good little motor to get.I think you might have some fun watching the Dynamite explode, catch on fire etc.

Sean

Just in case any one was interested, here is a link with pictures of my XXX-NT. Just scroll down a bit and there will be a thumbnail. Click on it and there you go!

www.TeamPlatinumRacing.com/Rides.html