First RC and starting with Nitro and I'm Clueless to how i assemble it. Any help is awesome.

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Fix the TRX 3.3 or go with the never ran os max 18?


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NewToRc&Nitro

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I just got a pre owned nitro jato a few weeks back and the engine attached was a TRX 3.3 and the previous owner had broken the piston rod, he made sure I was aware and gave me a Discontinued OS Max 18 cvr nitro engine that has never been ran with it. How do I piece this thing together and should I just buy a new piston for the 3.3 engine already attached or should I go with the OS engine as I've heard its a uncommon and expensive high performance engine? Both engines are missing the pull starter and the OS replacement starter is $50 alone so I just need advice on whats more worth my time and effort and money when it comes to this jato. Also most of the chassis and body are upgraded to alum parts. Ill attach photos to the post and thanks for any help.

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monstertruckier15

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The os .18 cvr You have is the non pull start version. It dosen't have a pull start. The conversion kit is not available (new crank shaft, starter shaft, new back plate ,one way bearing and starter well over $100) . So that won't work. You can buy a new connecting rod for the Traxxas engine $30 but more may be wrong with engine. You can use the Ez start for the Traxxas motor. I would check the condition of the piston and sleeve. Push the piston threw the sleeve until it stops. If it stops short? its good. If it goes threw the top? I's bad. A new rod and piston kit is $100. A new short block less carb and starter is $135. Sell the .18 crv and use the money for the parts you need.
 

D3MON

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the O.S. is far superior quality than the TRX, but as said above its a bump start engine, so would need a bump/starter box to start it.
if the con rod snapped there is a good chance that the piston and sleeve, or primarily the sleeve has been damaged, but piston and sleeves are matched, at the price it would cost to rebuild the TRX, i would get a dynamite .19 Mach 2 for 110$, better power, better carb, more ports for top end power.
ever since the re-design of the conn rod on the TRX 2.5 and 3.3 they are much more known to fail, and engines themselves are OK power. but the extra power the 3.3 has over the 2.5 it tends to split the rod down the center prematurely unless you replace it every gallon or two so prevent failure while running and ruining the internals.
depending on condition of the O.S. might be able to sell it (if you dont want to go for bump start), and have enough from the sale to pick up the Dynamite .19.
 

monstertruckier15

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Rebuilding the traxxas engine is the cheapest route. The rods rarely break unless you lean the engines out and use fuel with less than 14% oil lube. I have 10 traxxas engines and haven't broken a rod yet. The piston sleeve doesn't get damaged from a broken rod. So they may sill be good. You will have to check it out as I described. A classic example when you try and lean a engine out with less oil lube!
 
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D3MON

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Rebuilding the traxxas engine is the cheapest route. The rods rarely break unless you lean the engines out and use fuel with less than 14% oil lube. I have 10 traxxas engines and haven't broken a rod yet. The piston sleeve doesn't get damaged from a broken rod. So they may sill be good. You will have to check it out as I described. A clastic example when you try and lean a engine out with less oil lube!
70$-80$ piston and sleeve, 20-30$ for bearings, 20-30$ for a conn rod, already right there is 110$ and thats hoping the crankshaft hasnt been damaged or worn con-rod pin, crankcase hasn't been damaged etc.
oil doesn't compress as much as fuel and air... it will be harder on the rod to try to compress the chamber to cause ignition, running too much oil does no favors to save excess strain on the rod.
running too lean or over-revving them also will cause them to fail, but at the ratio of them compared to other engines failing, and all the material removed when the rod was redesigned, and the omitting of the oil hole, yes it is a part fault causing them to fail more often than most any other engine.
metal spinning at over 30-40k RPMs can damage alot, punching holes in the crankcase, marring the piston skirt, jamming into the sleeve against the piston, and as said they are a matched set, so if you buy one, you have to get the other or it will not work correctly.
 

monstertruckier15

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Compression has nothing to do with the connecting rod breaking. it has to do with friction and oil lube. Oil lube reduces friction. Less oil and leaning out the engine will damage the rod causing it to break.
Piston and sleeves are always sold as sets . That doesn't mean you have to buy a new one if the rod breaks or replacing other parts just to drive up the cost to justify a new engine. I have rebuilt many used engines with used parts and I don't match piston sleeves once used. I always save old parts as the can get some life out of them. All that matters is that you still have a pinch. In many cases there is no need to buy other parts that what is obvious needed. When a rod breaks I replace the rod and clean the engine inspect it for other damage and it's good as new. I bet Op doesn't have to spend what you say to fix engine. He doesn't need all the other parts you say! :eek:

I will give a used good rod for free. Or check you LHS store and see if they have used traxxas engines. There's no need to buy a new part if you can find a used one.
 
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D3MON

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i was agreeing with you and now I'm wrong for agreeing? i never said he would for sure need it as said in my first comment... i was agreeing with part of your first comment saying that more parts most likely will be damaged? i was trying to just help the guy and elaborate more, and give him some insight and what to expect as with my experiences and what I've seen with con rod failures, and alternatives if that was the case.

i won't and will never recommend mixing and matching pistons and sleeves unless they are already used and do not have another matching piece for them rendering them unusable otherwise, also judging that this is his first nitro, i doubt he has a stockpile of pistons and sleeves to to try to match up to make work.
 
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monstertruckier15

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I have 30 yr's experience with nitro engines and have only broken a few rods. The engines were used and You know what to expect with used engines! The only thing I had to replace was the broken rod. Nothing else. I cleaned the engines out and put the new rod in and they are still running today. Don't go and say that he is going to have to buy a bunch of new parts when in fact all that is broken is the rod. Making a big deal and spending someone's else's money. I gave good advice and the Op can make there own decisions. Buying a new nitro engine is expensive and A dynamite engines is more expensive than fixing what he's got. It all come's back to engine breaking and tuning and oil lube. When a rod breaks it's because the operator leaned out the engine too far running wide open too soon and not enough oil lube.
 

D3MON

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I have 30 yr's experience with nitro engines and have only broken a few rods. The engines were used and You know what to expect with used engines! The only thing I had to replace was the broken rod. Nothing else. I cleaned the engines out and put the new rod in and they are still running today. Don't go and say that he is going to have to buy a bunch of new parts when in fact all that is broken is the rod. Making a big deal and spending someone's else's money. I gave good advice and the Op can make there own decisions. Buying a new nitro engine is expensive and A dynamite engines is more expensive than fixing what he's got. It all come's back to engine breaking and tuning and oil lube. When a rod breaks it's because the operator leaned out the engine too far running wide open too soon and not enough oil lube.
wow thanks for putting words in my mouth that i never said, if thats what you think i wrote, might go re-read through what i wrote again?
funny thing is i AGREED with YOU in your advice that likely more may be wrong with the engine, now you are saying that i am trying to force him to buy stuff when i was outlining what items typically fail or should be replaced when a con-rod goes...
 
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monstertruckier15

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No other parts are going to fail if the rod breaks. Driving up the cost to justify a new engine. If that is the case I doubt it then the Op has to decide the best option. I already offered a free rod. So no investment yet.
 
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