That is very true. But mine had none of those issues. This Traxxas 3.3 engines carb mod allows the carb gap to be set to 2mm. Contrary to all other advice that say 1mm gap is the normal setting. It won’t work any other way. I believe it is the only reason this works.
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Traxxas 3.3 wont idle.
- Thread starter MrAllthat
- Start date
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monstertruckier15
RCTalk Addict
The stock carb gap is 1mm and that is factory setting. + 1/2 turn is ok. I suspect you have something more wrong if you have to open 2 mm. How are you setting the low needle. It should be flush with the barrel not the ball linkage ( if you set to ball linkage then 1 turn in or .020 in). The high should be 4-1/2 to start but don't go past 4 turns out. You may have blockage or crap stuck inside needles. or the carb body is bad. Once the idle screw hole strips out. I would just buy a new carb. As for using super glue it just doesn't work well.
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Very true about the gap. Everything else is set to all standard settings. High-Low needle flush. It’s a new carb as-well. It’s a bit crazy. It won’t work unless the gap is 2 mm!
monstertruckier15
RCTalk Addict
All I can say is High idle is due to compression loss or a air leak or junk is blocking the needles. I just messed around with a 2.5 r engine and had a same problem. It would only run with the idle open past 1 mm +1 full turn. It would run high. I put the carb back on another engine and it ran fine with the factory settings.
Your probably right however, when I rebuilt this engine I did a water compression test. I believe all nitro engines lose some air. This engine is not on high idle although it is set to 2mm idles as it should. If I was to remove my mod and revert back to 1mm + 1 full turn it would not work. All my other nitros have never had an issue like this and all carbs are set to 1mm + or -.
monstertruckier15
RCTalk Addict
I think the piston and sleeve is worn past usage. I had similar problems with other engines and it came right back to this. I can't put a compression gauge on to see what it is but I it turns over real easy and no popping sound. I know when OS engines go bad but because of the tall head I can't do a reading traxxas engines.
I am expecting a brand new carb for my 3.3. When it arrives I will make another video showing that this Traxxas will not idle with the new carb. It will run on high revs until you want to idle or brake the engine will simply stall won’t idle. Why don’t you try to the mod to the carb?
monstertruckier15
RCTalk Addict
The high idle has to be because the piston and sleeve are worn out and it has to rev high to keep the motor running. The factory idle setting is correct. A new carb will do the same thing. Remove the piston and sleeve and see if the piston goes threw the sleeve to the top or past. The pinch is gone!
the only thing you can try is fuel with more oil lube. 18% oil lube. I don't know how much your using now but More oil lube will bring back a engine depending on how use it was? Less is only going to make the engine run worse.
the only thing you can try is fuel with more oil lube. 18% oil lube. I don't know how much your using now but More oil lube will bring back a engine depending on how use it was? Less is only going to make the engine run worse.
Good advice. However it seems to me that you believe this engine idles high? If that were true the wheels would never stop spinning? I use 20% fuel. Surly if what your saying applied to my engine my mod shouldn’t work because the wheels would never stop spinning on high idle setting?My wheels do not spin.
monstertruckier15
RCTalk Addict
The piston sleeve is worn out. The high idle has nothing to do with wheels spinning. they engage at a certain RPM. The high idle has to do with the engine not getting enough air fuel mix due to low compression. The pinch is gone. A new carb will do the same thing. Once you loose compression the engine needle setting change and you will notice problems and try to adjust for it but nothing will work. Only a new piston and sleeve will solve the problem.
I respectfully disagree. This idles correctly and not high as you say. If I was to open the idle speed screw on any other nitro engine I believe the wheels would never stop spinning. When I set my idle speeds I make sure the wheels don’t move all. The idle is the rpm and this engines rpm is amazing. If as you say I fitted a new carb (without my mod) and open the speed idle screw fully it would not idle ever. It would start at high rpm but once you try to idle it would stall/engine cuts out.
monstertruckier15
RCTalk Addict
You can disagree but the truth is the idle should be set to 1mm or just above the engine stop running. NOT 2mm open. That is not correct setting and you have a problem. Which is the piston and sleeve is worn out. The engine needs more air and fuel to start and run due to the low compression. A compression gauge will tell you that. But you will never admit to it.
As for the fuel 20% is the nitro content NOT the oil lube content. I expect you fuel is less than 14% which isn't good. More oil would help your problem but it may be too late. If you have gone past 4 turns open on high needle then your engine is defiantly to late. With less oil lube you should stay away from 4 turn or less open.
This truck has a double clutch system and setting you idle to where the wheels just start to spin is bad.
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I will do a compression test just need to buy a tester. My high end needle is set to 4 turns from closed. I adjust it max 3/4 turns clockwise until I find the sweet spot of high and low mix. I am not saying you or I are correct. When I was first looking for a solution to my “won’t idle” issue none worked. I believe you would change your mind if you heard it and ran it. The only difference between mine and other setting is the 2mm carb gap!
monstertruckier15
RCTalk Addict
So you have turned past 4 turns on high
3-1/4 And you leaned out the engine of fuel and oil lube. No wonder your idle is set to 2mm gap. Good luck finding a compression gauge that will work for the T maxx engine. Very expensive. I run my trucks @ 4-1/4 high and low 1/4 turn out from flush and idle 1mm open. All run just fine. Fuel 15% nitro with 18% oil lube. High idle is from low compression from factory setting. 4 turns is factory start after break in but what you didn't know is 4-1/2 turns is set at factory down to 4 turns after break in. Past that then you lean your engine out. You don't start at 4 turns and break in to ??? there is always a 1/2 turn for break in.
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I seems like you read my reply incorrectly. The manual for Traxxas states: Factory needle settings for high-speed needle to 4 turns from closed. Like mine. Not sure how you read it past 4 turns. Usually I turn on from there not out. My engine runs and ladles perfectly at 4 turns from closed.
monstertruckier15
RCTalk Addict
Turning in means you lean it out the engine less fuel less oil lube. Anything turned in less than 4 turns from out is bad You said it again. That explains the high idle gap you have. I never start a 4 turns out and turn in to tune. I start with 4-1-2 turns out and work down to 4-1/4 turns Not going past 4 turns.
Well I guess it’s a matter of opinion. I’m sure there is a Traxxas official (I believe) YouTube video which shows you start 4 Turns out (as in manual) and lean the mixture until you don’t hear anymore improvements. You run your engines very rich in my opinion. I will set up mine like yours 4 1/2 turns out and work down to 4 1/4 turns. So in your opinion if I set my carb like yours only keeping my 2mm gap my engine shouldn’t idle or run?
monstertruckier15
RCTalk Addict
The high needle has nothing to do with idle. It' has to to with max speed and proper oil lube protecting the engine. Leaning out the engine turning in can damage the engine. 4 turns to start in the manual is for if you lost your settings and to start there. It doesn't mean keep on leaning out the engine from there. Most nitro engines have a tuning window. Example 1/2 -5/8 of a turn . So when you reset the carb back to suggest 4 turns you don't have that 1/2 turn anymore for tuning. You may only have 1/16-1/8 turn. It's best to stay away from the max setting to protect engine.
I start my engines at 4-1/2 and turn down to 4 turns which is the suggested setting if setting is lost. This way I know I am safe. Such factors as oil lube will make tuning different. Your problem is from you went past the 4 turns with low % oil lube and leaned out your engine and this caused the idle to be change to keep engine running. This is loss of compression. I can only suggest more oil lube in fuel to remedy the problem. 18% oil lube is what I run in all my engines. It has helped with some engines and improved the performance.
I start my engines at 4-1/2 and turn down to 4 turns which is the suggested setting if setting is lost. This way I know I am safe. Such factors as oil lube will make tuning different. Your problem is from you went past the 4 turns with low % oil lube and leaned out your engine and this caused the idle to be change to keep engine running. This is loss of compression. I can only suggest more oil lube in fuel to remedy the problem. 18% oil lube is what I run in all my engines. It has helped with some engines and improved the performance.
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monstertruckier15
RCTalk Addict
The high needle has nothing to do with idle. It' has to to with max speed and proper oil lube protecting the engine. Leaning out the engine turning in can damage the engine. 4 turns to start in the manual is for if you lost your settings and to start there. It doesn't mean keep on leaning out the engine from there. Most nitro engines have a tuning window. Example 1/2 -5/8 of a turn . So when you reset the carb back to suggest 4 turns you don't have that 1/2 turn anymore for tuning. You may only have 1/16-1/8 turn. It's best to stay away from the max setting to protect engine.
I start my engines at 4-1/2 and turn down to 4 turns which is the suggested setting if setting is lost. This way I know I am safe. Such factors as oil lube will make tuning different. Your problem is from you went past the 4 turns with low % oil lube and leaned out your engine and this caused the idle to be change to keep engine running. This is loss of compression. I can only suggest more oil lube in fuel to remedy the problem. 18% oil lube is what I run in all my engines. It has helped with some engines and improved the performance.
I start my engines at 4-1/2 and turn down to 4 turns which is the suggested setting if setting is lost. This way I know I am safe. Such factors as oil lube will make tuning different. Your problem is from you went past the 4 turns with low % oil lube and leaned out your engine and this caused the idle to be change to keep engine running. This is loss of compression. I can only suggest more oil lube in fuel to remedy the problem. 18% oil lube is what I run in all my engines. It has helped with some engines and improved the performance.
