Do i need a new engine

[Paul11277]

Hi all. My maxx is playing up big time now. It will only idle at half throttle. Which means i have not breaks because the minute i apply the breaks it stalls because it less then half throttle. I have tried many many many setting on the carb but nothing works i have to trim it to halfway throttle on the remote for it to start. Its also very difficult to start and its blown glow plugs like its some kind of hobby the engine has. Its the standard trx 25 engine. Never really had it running well at all. I fitted an over sized head and this did improve it a lot. But its still never been perfect. It blew 2 plugs yesterday on the same tank of fuel. The head bolts are tight the plug is tight the carb setting are flush on the lsn and 3 turns out on hsn. Have tried opening the lsn right up see if that cured its idleing problems but nothing. changed all fuel lines and air filters. The engine does have compression and on stripping it down a little i noticed small fragments chipping off the bottom of the piston. I cleaned all these because they would cause it to lock sometimes. But the surface and the fit between the sleeve and piston seem perfect no leaks or or scores on the sleave or anything. I still have the original trx 15 engine which to be fair seemed far more reliable and only lacked in torq the speed itself was very simlar really. I have probably not had more than 2 gallons of fuel through it and even thats probably exagurated as i can only actually find 3 half gallon containers of tornado 25% in the garage and thats the only fuel i use. Hope someone can help.

 

[kswiencki]

did you try adjusting the idle speed screw?

 

[mattykane]

okay my megatech .16 was doing the same thing. if any fragments of metal from the bottom end come apart they make their way into the combustion chamber part of the engine and ruin glow plugs left and right. the reason this happened to mine was because some jackass that had it before me had run it without an air filter and it had sat for sometime without one so when i started running it it disturbed all the dirt that had settled in the bottom which made it a bitch to tune and it ate glow plugs like 8 in 3 days
My suggestion to you is to pull the motor apart as much as you feel comfortable doing and flush the crap out of it. i used a a compressor and a glass jar filled with gas..I havent had a problem since. hope it works out for you. -matt

 

[brad55102]

I think the real problem is the idle, But First.....
CLEAN your mil ASAP, DO not run it again until it is completely clean. Take it down to its last part and clean, then lube everything. Check the compression by putting the piston into the sleeve while you have it apart. It should come near the top but not all the way up.
After you have doe this, seal your mil. Use the copper ATV sealant.
After that, reset the carb to the factory settings and start over.
Let me know how it goes.

 

[Paul11277]

did you try adjusting the idle speed screw?

Where is the idle screw. i thought on the traxas engine the lsn and hsn where the only settigs on the carb.

 

[BradZ]

Underneath the air filter. Small screw.

 

[Paul11277]

Oh yes i see it thank. well i have stripped mist my engine. con rod and everything is fine. there is some damage to the bottom of the arch on the underside of the piston. I flushed it through with some old fuel i had in the garage and did it through filter paper su i could see if anymore fragments came out. There where a 2 tiny tiny bit, but no where near as much as i got out when i did it once before. So my question is now. Am i better off changing the piston and sleeve or just running it till the piston gives in. I have a trx 15pro which i intend on exchanging for the trx 25r anyway at somepoint. So even if i do kill the piston in the one i have now i am thinging it is going to make a better spare than my 15pro. Ok it might not be a runner by then but most the parts are the same. My current 25 still has lots of compression too even though the bottom of the piston has some damage the surface and sleve are perfect.