Top-cop-nj

As most of you guys already know I ordered an xtm 457 and it came in this week. After doing the standerd break in over the past few days I began to tune her up and no matter what I do I can't get it to not take off unless I hit the brake which ends up with it dieing. I've adjusted the carb idle screw and the trim on the radio and it's still being a pain. I've tried adjusting the low end/ idle screw to balance it out but to no aveil, I sealed the engine so I don't think it's a leak from the engine. I did change my fuel lines when I got the new engine but I see no bubbles in the line so all seems well there. The weird thing is the throttle will BARELY be open but she revs like a beast, has anyone seen this before?

P.S. I played with it for awhile to try to avoid another troubleshooting thread but I'm desprate.

alvinl

Make sure the trim on your radio is set in the middle, at neutral. Then adjust the idle with the idle screw. If your throttle trim is not set in the middle, your servo can move past the idle position when you hit the brakes. Weird, but i've seen it happen many times. Also, it may take a gallon or so of fuel before the motor really settles down and holds a tune.

bagolies

The same exact thing happened to me. It drove me nuts for awhile. It wound up being a broken clutch spring.

Top-cop-nj

I've exausted all possible things that come to mind, I have to turn the trim way down because if it's at middle it will take off hard and get into second gear on my three speed. Holding the tune isn't my problem the problem is that the truck won't stay still no matter what I adjust, if I brake fully it stops then dies.

46u

My Feedback: (3)

If I understanding what you are saying does not sound like the engine sounds like a clutch problem. Are you 100% you have the clutch installed properly?

46u

My Feedback: (3)

If I understanding what you are saying does not sound like the engine sounds like a clutch problem. Are you 100% you have the clutch installed properly?

One other thing after break in did you adjust the HSN first then the LSN?

Top-cop-nj

yea, I put the clutch together as I did the one before. I adjusted the hsn then the lsn, is it possible the clutch set came off-set after I put it all back together?

Chronic

A broken spring will cause problems very similar to yours, except for the revving up for no reason thing. Sounds like a leak to me.

Strange. Let us know what it was when you get it sorted out.

Top-cop-nj

I don't see how it could be a leak seeing as I sealed it, anyhow is there anything I can do to see if the engine does have a leak or should I just take it apart and reseal it?

Chronic

Whenever I have a tuning issue anything like yours, I automatically start looking for leaks. All it takes is one time pulling your hair out over unexplainable tuning troubles only to eventually find a leak, and you get paranoid about them. Yours is already sealed though, and it might not be a leak at all. I'm no RC engine expert, but that's what it sounds like to me.

What did you seal? Backplate and carb throat? What about the needles? Orings look good? Needle fittings nice and tight?

Have you checked the fuel tank? Submerge it in a sink full of water, leaving the two hoses sticking out. Plug the feed line and blow into the pressure line. Bubbles mean a leak of course.

Top-cop-nj

I sealed the backplate, carb and the throat. I'll test the tank tomorrow and see, I got so fed up with this I was so very close to picking up the truck and throwing it.

bennyblanco

but it still sounds like the clutch!!

46u

My Feedback: (3)

I agree with savage.27 I say check the clutch as well as make sure the bearings are fine, the CB spins and so on. Being you say you have to hold the brakes to keep from moving and then it dies. Sure cannot hurt to check it.

badboy2

My Feedback: (13)

make sure u r using new bearings on the cb..and also could be a loose clutch spring..also make sure the servo horn is centered ..

JayC1968

My Feedback: (3)

I swore I would not return to this forum BUT I see you have an XTM issue......
If you have to hit the brake then it's a linkage problem or a trim and or both... Take the horn off the servo and center the servo with the trim. Put the horn back and re-adjust the linkage for a true 90* servo setting.
After break in with XTM's you will to lean it up a considerable amount as the XTM's break in settings are WAY richer than most.
Xtm's like rich low speed needle settings.
Keep in mind that there are 3 needles. (I saw you said low end/idle) The low end is on the end of the thottle barrel.

It simply sounds like you went overboard in tuning
From what you say it sounds like you need to richen up both the HSN & LSN and open the carb up some to get close to where you need to be, but to be honest I myself would return it to FACTORY settings and start from scratch.

The Factory settings for the XTM 457 are:
HSN= 3.5 turns out from closed
LSN= 3 turns out from closed
ISN= 1mm open

In case you need it........ here's a link to the 457 Pro Engine manual
[link=http://media.hobbypeople.net/manual/146032.pdf]XTM 457 Pro Truck.PDF[/link]

ThunderbirdJunkie

My Feedback: (3)

Jay, I thought the needle settings were flush and flush on the LSN and HSN?

JayC1968

My Feedback: (3)

Nope..... read the .pdf I linked to above.....
Did I mention that the 457 likes MEDIUM heat plugs?

BTW TBJ...... when you say FLUSH is not a good judge in setting... as FLUSH has almost a half turn to 3/4 turn before it can be noticed.
When I give settings it always from closed with VERY little restriction when closing to avoid crimping the o-rings. The very first sign of resistance is closed to me. I also at the first step before firing up an engine is lube all needle o-rings with Associated Green Slime as I seal the engine.

savagelover

linkege......

Top-cop-nj

I took the engine out of the truck today and the cb seemed alittle tight, so I removed 2 of the shims that was over the cb and she no longer takes off on me. It's running well now, this thing runs best at 210 degrees. If it lean it out any further it bogs down and doesn't run smoothly, so I have it set up well as of now and let me add this thing is POWERFUL!

bennyblanco

im glad you got it fix!

Chronic

What was causing that?

Top-cop-nj

No f-ing clue, it runs good for now so I'll just run the hell out of it.