Trucks Tmaxx 2.5 'rebuild'

bigone5500

bigone5500

Well-Known Member
Needles are at factory break-in settings. High side is 2 1/2 out. Low is flush with the slide. I'll get another vid.
 
bigone5500

bigone5500

Well-Known Member
I have a hard time doing it. I talked to the guy today who I bought it from. He said he may have ran it 4 or 5 times so I don't really think the engine is worn out. I think it has just about as much compression as my new one.
 
bigone5500

bigone5500

Well-Known Member
My neighbor used to fly nitro RC helis back in the day. I'll take it over there tomorrow and see if he remembers how to get it running right. That's assuming they are the same.
 
Tony

Tony

Staff member
I can run an engine one time and destroy it. In fact, when we were locked to only a .12 size engine in 1/10th scale Nitro Off-Road, I would put a fresh build in at the beginning of the main. Now, my engine was not stock with a VERY heavy port job, knife edging the crank to the max and cutting the cam to not only lighten it for higher RPM but also adding a groove to 'sling' fuel into the engine. I had these engine screaming during the main, but the engine only lasted one race. Hours of work, Gone in a 5 minute race. But all of the wins was 'almost' worth it lmao

So don't take what he said to mean the engine is perfectly fine. The engine should start and run with stock settings, but should be slow and absolutely PUKING fuel out of the exhaust. If it is not running, then there is something wrong. Judging by the smoke and the way it sounded in that very short video, it sounds lean to me after watching a few times. You leaned it out per my suggestion, now, take that 1 hour on the low and the 4 hours on the high and remove them. Back to completely stock. Now, go the opposite way. 1 hour richer on the bottom and 4 hours richer on the top.

This is a DRASTIC change, but it will tell me a lot.
 
Tony

Tony

Staff member
bigone5500 said:
My neighbor used to fly nitro RC helis back in the day. I'll take it over there tomorrow and see if he remembers how to get it running right. That's assuming they are the same.
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They are most definitely not all the same. Airplane engines, you fire them up, once they are running and a little warm you hold it nose to the sky (making the longest and hardest pulling distance for the fuel) and you lean that sucker out until you hear MAX RPM! That engine is now tuned for THAT DAY! Humidity and pressure will affect a tune in a drastic way.

Nitro engines in a car or truck rely on a lot of Passive Cooling rather than active cooling like you get from the prop on an airplane engine. On a car or truck you need to tune it after running it hard for a minute or two and temping the head. If you don't have a temp gauge, get one. It is the best investment you can make when dealing with ground pounders.
 
bigone5500

bigone5500

Well-Known Member
I have a fluke 62 that I can use. I'll tinker with it more tomorrow. Surely it's not worn so bad that I can't get it running.
 
Tony

Tony

Staff member
The fluke will read good for static temps, but instant temps, you really want an inferred thermometer. Trust me, best money spend when it comes to these engines and long life. Point and shoot, like a cell phone camera!

and try the richening deal I mentioned. if it helps, let me know because I probably know what is going on...
 
bigone5500

bigone5500

Well-Known Member
My parts came in today. I'm going to focus on installing the new bulkheads and if I get time I'll rebuild the shock. I also plan to change all the shock oil to 40W. I want to see the difference in the two trucks with different viscosities.
 
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