The o-rings on the needles will dry out over time so they very well could need replacement. The o-rings on the needles are really small and are sometimes tricky to find. I ended up buying a couple o-ring kits for various engines to get the sizes I needed. I would take the carburetor to a hobby shop and see if they can match up some new ones.

I found a new xtm 24.7 on eBay for $45 so I went ahead and snagged it as a back up

Well I rebuilt it and I'm at a loss...factory 3.5 1.4 this that and the other and it won't run right..

If I gun it falls on its face and dies instantly

Factory settings on the high speed and low speed needle are way too rich for a broken in engine. Try to lean them down 1/8 turn at a time until it revs up nice going WOT. If it loads up really bad idling, lean the low speed 1/8-1/4 turn so it will idle and not totally load up and work to get the high speed set before fine tuning the low speed.

Thing is I've read hsn/lsn 2 3/4 2 1/2 then I've read 3.5/ 4.5......

I did see milky glob come out the pipe when I fed the throttle..

I think carb is all over the place...And possibly junk..

And I know one needle is over compensating the other but which one since ex .28 is so vague

The base setting for the low speed is having the needle backed out so the screw head of the needle is flush with the throttle arm. It doesn't really matter how many turns it is if it's set flush with the arm. For the high speed... If 2.5 isn't allowing it to rev up, try 3.5. If that doesn't work, open it another 1/2 turn until it does. If the main needle (high speed) screw head is flush with the holder tube or close to it, change the o-rings for sure.

Flush how?

Gonna try again today..

Read somewhere that 2.5 is lsn and 2 3/4 is Han

Seeing that Brown glob yesterday says either overly rich or poor compression piston shot

I did notice the rod was new but never saw rings come to think of it. Is there

Nevermind I know what flush is


Really appreciate the help thanks

She is running now

At the top end she cut out like out of gas so I riches it by 1 hr increments till she flew but no second gear??

I'm almost there

Usually the transmission won't shift if the high speed is too rich. Once you get close to a good setting, it will start shifting.

Remember I'm salvaging a basketcase so everything is suspect...

But I will run it some more ...had to rewind pull cord...so if i Can rewind that this nitro is about licked lol

Ok got another problem ....I'm either stuck in second or first is that tall ..I'd say top speed is 35mph

Flywheel isn't factory and does it matter
Clutch shoes one side look new other side look distorted and wore weird.


I went by factory turns 9 1/2 out from bottom by xtm manual..

What else could keep it from shifting?

And can order any flywheel and shoes since xtm are scarce and junk....and what kind? What's good?

Thanks

35mph on a stock MT is pretty good. It may be shifting and you're just not hearing it. If it was stuck in first gear, it would top out at about 15mph. You should get a manual with exploded view of the transmission setup so you can take it apart and make sure everything is properly adjusted and in working order. I also suggest posting pictures of the things you aren't sure of - example is the clutch shoes. There are different styles used on different trucks over the years and since we don't know how much your truck has been messed with, pictures help determine what you have and how to determine what's wrong if anything and how to fix it if needed.

9.5 turns out on any setting sounds like a LOT..

9 1/2 does but that's what the manual said and I downloaded all of them.

Clutch is a 3 shoe style if that helps

9.5 turns on what?

The 1.5 set screw maybe I read it wrong?

Xtm mammoth mt manual

You must be talking about the set screw in the 2spd hub? Check to make sure there is only one screw to adjust. Some 2spds have two screws.

I found two but one is 2.0 and that takes it apart

I gotta wait for my new servos since these scrapped out and yup throttle while driving luckily it died with throttle closed..


Btw I got that .15 screaming max temp 250° then the tank cracked or son thing cause fuel was leaking from the bottom

Anyways thanks again for the help

Me again!
Put a new 24.7 in it broke in and it runs great temps are 200 to 235 depending on how hard I run it. Idle temp 160 to 180 ..temp gun record s highest and average temps.


Installed new 3 shoe aluminum with heavy spring

Problem....

No shifting at all

I even held it and saw for myself

The adjustment screw has went from tight to loose still no action...it acts like a center diff.

Sad part is my losi lst that is electric with a mamba 2 and 1700kv motor can't even touch this truck from a dig and top end.

So I'm not sure what to do next

If you're sure it's got a 2-speed transmission, then you need to probably pull the 2-speed apart and clean it. The 2-speed hub may be damaged or the drum the hub runs in could be as well.

What about a spring and rod? I just read on another forum about that..

I guess I'll have to tear the center out

Are both gears pinion to be lined up and meshed to the spur gears?

That's the way I did it going by pics and old manuals

http://www.rc-recycler.com/media/cat...70000_0924.jpg

According to the exploded view I saw of the transmission setup, it appears that there is a 2-speed hub clutch that uses a small pawl that pops out when it's spun fast enough and that pawl should engage the inside of the drum that covers the 2-speed hub. If the spring or pawl breaks in the hub, it won't shift and also if the "catch" in the 2-speed clutch drum is broken or damaged it won't shift. It appears, based on what the drawing showed, that the 2-speed works similar to that on the jato. The screw in the 2-speed hub controls the shift point - tighter screw = later shift, looser screw = earlier shift. If the spring under that screw is damaged, it may not tension the pawl correctly.

I'm just going on what the parts diagrams showed. I've never dealt with a center diff equipped truck.

The diagram I used: http://xtm-dealer.com/Mam%20explosion.html

No your right and prior owner abuse has been evident so I think it got over tightened or not there ( the spring)

So more digging

Good luck. Sorry I'm not more of a help.