My new XTM mega monster truck (mmt)

Welcome to RCTalk

Come join other RC enthusiasts! You'll be able to discuss, share and private message with other members of our community.

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.

gsbuickman

RCTalk Basher
Messages
62
Reaction score
26
RC Driving Style
  1. Bashing
  2. Racing
Hiya Guys :) . I know it's been awhile but for the last several years I put my ground vehicles on the back burner and focused mainly on my fast electric offshore boats instead. The rc boating around here has come to a standstill and I got tired of running by myself so I let them go and picked things up with 3 new 8th scale rigs, of which this is one of them.

I don't know why but I've always been a fan of global Hobby, xtm and I've had my fair share of them but I've never had a mega monster truck before so this is my first. I've had a number of 8th scale rigs like the Genesis, LST XXL & Savage 5.9, so I can honestly say this thing is a beast although it's not quite as wide as what it should be it still gets the job done. the gentleman I bought it from picked it up new then he took it home and parked it after which it sat there because his friends got out of Nitros and he didn't want to fiddle with it by himself. So , it's out there collecting dust until he got tired of looking at it and sold it to me for $200 , needless to say it was money well spent.

DSCN3796.JPG DSCN3797.JPG DSCN3794.JPG
 
Yep, both the mega monster truck and the mammoth AR bigger than my LST , as in they're both wider and longer.
 
Killer rig! Awesome score on the find (price)!
 
Thanks, this also came with a big box Child full of all his miscellaneous Nitro stuff because he just wanted to get rid of it all. I dug through the box of stuff and filed most of it in the garbage can but there were a few miscellaneous Parts here and there that Ikept, but I also found an Ofna hyperforce. 25 with the head off but otherwise complete amongst the stuff.

it had been sitting around long enough open like that, that everything was gummed up so tight the rotating assembly and carburetor were frozen solid. I disassembled it and with the help of a lot of WD-40 and some gentle persuasion she finally came unstuck so I continued working on it until she was free and spotless clean. I put it back together and I bet money that this motor had never even been run as tight as the pinch is and the compression it's got. after going through all those parts and filing most of them in the garbage I was beginning to think that maybe I should have dickered him down on the price a little bit, but with the way this new motor turned out it's all good. Now I have a force. 25 & a Mach. 21 for backup Motors if either one of mine goes south.

IMG_20161016_225440.jpg
 
Nice!!! Have you gone thru the carb as well? Thinking of the motor was as bad as you say, the carb has to have been stuck similarly.make sure all your valves and the butterfly/slide is smooth as silk now. Replace the o-rings, get a lil green slime in there! (the associated stuff, not the gunk you're removing now!) If it's as tight as you say, and the bearings are perfect, it will run beautifully!!! Way cool, this deal just keeps getting better! Like they say in 'football' (sort of) SCOOOIOOOOOOOOORRRRRRRRREE!!!!!!
 
Yep, I don't know how long he had it sitting around like that but it was gummed up good, thankfully it cleaned up real nice. now she's clean and skins free. rather than mess with the carburetor I was going to put a mach or xtm carb on it but they wouldn't fit. So I took this one apart and went through it as well and got it cleaned up and installed back on the mill.

there were 4 Motors in that box of stuff but this was the only one that was salvageable. coincidentally the other three motors that word junk also happen to be HPI purple head Nitro star big block Motors like the ones that come on Savages, and I can tell you from personal experience their absolute crap just like Traxxas motors are.
 
I haven't a clue as to what the you motors are about other than a few friends who would run their savages with me. Its funny, don't misunderstand me, I am not one to promote the traxxas motors... I know what they are... However... I have 2 traxxas 3.3s and they both run super strong and have been very reliable for me. I guess between breaking in correctly, proper maintenance etc and of course, tuning, I've been very lucky. I've seen a LOT of posts from ppl who have had nothing but bad luck, right from the get go with their traxxas products.
But back to your score... I would LOVE to see some video of that truck romping when you get it all right to how you want it (sounds like it's going great already!) They are such bad ass trucks!!!
 
Thanks, this Beast purrs like a kitten & runs as stable as a motor could possibly be. the first time I fired this Beast up I've lost some gas in the tank which is huge by the way and pulled the starter without priming it and she immediately fired up on the first pull. at the moment she only has 3 full tanks of fuel thru the mill. since this Beast has a big ass gas tank I only run half a tank at a time otherwise it takes an hour or more to run a full tank dry.

when I tune my big block Motors I set them to run according to operating temperature. my preference for Motors is Team Losi xtm Team Associated and Thunder Tigre mills. every motor is a little different butt depending on what the motors preference is for running the best, I'm looking for 190° - 205° when warmed up at a stable idle. after a high-speed pass I see temperatures around 220° - 245° @ the glow plug, according to my digital laser temp gun. as far as videos go, the only RC's that I've done nice HD videos of are some of the boats that I've had. one of these days I might have to do some of my ground Vehicles as well.
 
The XTM 24.7 wasn't a bad engine. A tad underpowered by todays standards, but ran pretty economically. I remember the tank on my mammoth st. The thing seemed to run forever. I ran one of those engines in my BB revo until it wore out and started flaming out on me and the OWB stopped responding to cleanings.
 
Yep, I can fill the tank on my Mammoth St with 20% O'Donnell or Duratrax Red Alert and it'll run for about 35 min before it lean burns and goes dry. the tank on this mega monster truck is a different story, it's a massive 290 cc's. when I started the break in process on this motor I learned the first time not to ever fill the gas tank full again, because it quite literally took an hour and a half to run dry running figure eights and medium speed passes up and down the street in front of my house. that was no doubt the longest break in tank I have ever run and from now on I only run it half a tank at a time.

I've never been a fan of temperamental little. 12 -.18 small block Mills however I have had a few that were surprisingly reliable and a lot of them that were junk. I'm not exactly a fan of .21 big big blocks either , but there are times when they are appropriate especially in lightweight buggies and truggies like my Mammoth St. I can run my mammoth St down to the end of my block and turn it around so it's coming back towards me down the center of the street and hold it steady at 1/3 throttle and let it build its own momentum and by the time it passes me halfway down the block I can clock it doing 60 mph before I have to get off the throttle and hit the brakes in case someone is coming around the corner at the other end of the street. some people may think he's xtm 24/7 Motors are a little underpowered but under the right circumstances they can still push a rocketship plenty fast. much like the monster .28 big block xtm Mill in this mega monster truck, this damn thing is a Powerhouse and provides all the power it needs and then some. With th the 7" tall tires, 4" of ground clearance and the 15 pounds of weight this thing gets moving so fast it can reach stupid speed real quick. with the rotating mass of these big ass tires and the tall ground clearance it reaches a point when momentum over takes control and you have to get out of it and get it back under control again.

http://www.rcgroups.com/forums/showthread.php?t=758037
 
I had no idea the tank was so huge in those trucks! I don't know why, but I find it amusing!
I would imagine getting one up to speed needs to be a well thought out endeavour! :hehe:
Even getting my revo going at too speeds requires thought so as not to destroy the truck, humans, wildlife... !!!
I would Def enjoy some video of you can find the help and time!
 
I have had that exact truck for about 4 years now. Tough as nails and flies over everything like it isnt there......

Mine has Redcat 17mm hex deep offset wheels and losi 420 series super bolt ons mounted and I changed to a Proline F 650 shell........

XTMMammothMMT018.jpg
as I got it from a buddy....

DSCN5028-1.jpg


Parts are hard to find here in the USA so I buy arms and such as I find them, otherwise it is a beast running the OFNA .32 engine in it now as I wore out the SH .28 it came with......
 
That's awesome, thanks for the heads up on those Red Cat Wheels. have you swapped out the dog bones for LST-2 dog bones yet ?. the problem I've read about people running the .32 Motors in these is they shear the dog bones and have to be upgraded to the LST 2 bones. after that it's party on...
 
Yes I got the Losi CVD bones to try on mine, when I got it one front was broken so I used the losi cvd bone....
 
I always think its a bad idea to have so much exposed to the elements on flat plate chassis like that. Definitely would never want to really run it through the muck.
 
actually in a lot of ways it's better because even when you do get it deep in the muck & mud there's nothing to keep the crud in, and it rolls right off the chassis. it's the same principal that applies to really good mud tires. the better they "clean" or get the mud out rather than the tires getting plugged up with it the better they work
 
Last edited:
I have not run mine in the muck and mud yet, but I bet it would do pretty well considering the size of the tires and all the power that .32 force engine has....
i just dont want to have to clean all the mud off the truck......
 
cleaning them is the easy part. you can shake the excess crud off then put a plastic bag over the air cleaner or a rubber plug or balloon over the carburetor Venturi, then drop it in the bathtub and douche It Off. if you really get it dirty give it an initial rinse off, then shake the excess water off of it and spray it down with simple green or Windex. then let it set for a couple of minutes and douche it off again. set it outside and let it dry after which Lube everything up with a little bit of WD-40 and you're ready to roll
 
Compressed air helps a lot to get the big chunks off... And no baggies required!
 
Back
Top