Man, I wished I had cleaned my carb, I had my Revo with a 3.3 and it sat for years. I pulled the engine, cleaned it up to the point it would spin by my fingers. Once it began to run, and get hot, the funk that was in the dirty carb let lose all the funk and spat it out of the loose glow plug hole. God I pray I didn’t screw up my engine.
First person I have ever seen that actually knows the low speed needle. Not that traxxas flush junk. Or the one that gets me the most is people say half turn out from closed.
I have a question, I can’t get my 3.3 to run when I floor it no matter how rich or lean it is I’ve tried the stock settings and it still never wanted to go when full throttle, and when it did do it for a second it would shut off after I let off of the gas, do I need to rebuild my carb?
I must admit Jason, this video came in perfect timing, my carb on my Slayer 3.3 needs cleaned, and this seems like the best video on rebuilding it. Great job!
RE: Tuning woes with REVO 3.3 The operating temps should be at 270ish, I run my engines at around 245-280 depending on the day. here the guide, I’ve just copied this from a file on my computer so sorry if there are some inconsistencies with your problems. (I’ll share this around. Cheers) now, for the idle being too high or too low, first set it back to factory which is 4 turns out on the high speed needle and 1.75 turns out on the low speed, start the truck and run it around to let it warm up, once you have it warmed up bring it in and let it idle, if it's to high you will need to turn the idle screw out maybe 1/4 or 1/8th of a turn, and see how it's idling then, if you can’t get the truck to start, give it a little bit of throttle, once the engine is warm it should start up very easily. then one you have it idling you can start tuning, when your tuning, go in very small increments at a time, and ALWAYS tune the high-speed needle first, I usually go by 1/12 or 1/16th of a turn at a time, but must guys go 1/8th of a turn, after each adjustment do a few high-speed passes, take very careful note of 3 things. 1. the performance, has it gotten better or worse? when you start getting the rpm up does it sound like it's cutting out? if it sounds like it's cutting out then you are to lean and need to richen the HSN, if it is loading up and the performance is very sluggish then it is rich and you can go a little leaner 2. the smoke trail, there should always be a nice, clearly visible trail of blue smoke coming from the exhaust, always, if you cannot see a good trail of smoke, it is another sign of being to lean, if you’ve a lot of smoke at all rpms then you can go a little leaner 3. the temperature, since this is your first nitro truck it is a good idea, you get a good, reliable temp gauge, the engine should not go over 270 degrees F, if it does it is another sign of being to lean and you should richen it up just a little bit, but something most people over look is that you should not run under 190 degrees, if you do the piston sleeve doesn't expand enough and the engine will wear out very quickly. a last note on the high-speed needle is, never tune by one symptom alone, never tune just by performance, or smoke trail or temp, use at least two, so if you lean the engine out and the temps go from 220 to 230, and you note it's a little more powerful and go a little leaner, the only time you should ever tune by using just one symptom is when: A: you run to lean and the engine start hesitating and cutting out B: the temp goes above 290 degrees F in both cases you need to richen the HSN by at least 1/8th of a turn if not more. now for tuning the low-speed needle one the high-speed needle is set to where you want it, you can start with the low speed, start off at the factory setting, and just like the HSN tune in small increments of at least 1/8th of a turn, if not smaller, when tuning the low speed, you are aiming for a nice crisp throttle response, if you run the low speed to lean you will eat through glow plugs very quickly and it can damage your engine. once you start getting close to what you think is the best throttle response, tune in smaller increments, once you get it so as soon as you touch the throttle the engine start revving up and doesn't bog down at all, so as soon as you hit the gas, the truck takes off, once you get to that point do not lean it any further, and for a safe guard i like to richen it by 1/16 of a turn. to test to see if the low-speed needle is set to rich or to lean you need to do the pinch test, all you do is pinch the fuel line, and count how many seconds it takes for the engine to die, when you pinch the fuel line, the engine should idle normally for a second or two, then just before it dies it should rev up a few hundred rpm, then die on the count of 3. if the engine dies in 2 seconds or less, or does not rev up at all, you are to lean and need to richen the low-speed needle, if the engine takes more than 3 or 4 seconds to die, you are too rich and can lean the engine out a bit more. for then engine not start, check to see if the glow plugs good, to do that just take the plug out, connect it to the blue glow wire, hold the glow plug up against the cooling head, insert the starter wand into the truck and press the red button, if the wire in the plug glows it's good, if it doesn’t you need a new plug, if the plugs good it may be because the engine is flooded, so you need to take the glow plug out, pinch the flue line, turn the truck upside down and turn it over with the start wand and see if that helps. once you have done all your tuning you might have to set the idle again, if you do just follow the steps I posted at the top of the page, you should never have to touch the idle screw unless the truck is idling high enough for the clutch to engage, or that low it won’t start.
One thing I've learned DO NOT use excessive force to screwing the carb needles in as it will knacker up the needle point. I use crt monitor stands the type that bolt onto the wall or bolt to bench to store car on so suspension is hanging free and you don't flat spot tyres.
As far as the fuel inlet nozzle goes, it doesn't matter if you get the nozzle exact, as long as it's close. The high speed housing has a hole, and if it mattered, you'd have to turn/crank the nozzle into the carb the exact amount of threads/tightness as factory.
I was wondering if you can make a follow up video of the Traxxas Tmax startup, tuning and running after you rebuild the carburetor. Thank you in advance.
hey its not really a trx 2.5 carb, its the same one on the 3.3, you should change name to something like "How To Rebuild/Clean/Take Apart A TRX engine Carburetor" or somthing like that, that way people can find the video a lot easier. its just a sujestion =)
Great explanation on the rebuild. I rebuilt mine a few days ago, and now I'm having issues with fuel getting to the carb. I replaced the fuel lines, and I keep getting air bubbles in the line to the carb. I have the Revo 3.3 with the long fuel line that wraps around the roll bar. After I put everything back together, I plugged the exhaust, and the fuel went right to the carb, but after it sat, it formed the air bubbles. I guess I just need to shorten the line on it to keep it from getting air in the line. Thanks for the video.
RakinBill glad to help out. Another thing that could cause air bubbles is the tank isn't completely sealed when running. Check the tightness of the O Ring for the Fuel Tank Cap.
darkeclipticheart It's a brand new tank, but I will check for air leaks. I used zip ties on the ends of the fuel lines to make sure they are sealed too. If I place my finger over the exhaust pipe when cranking, it fills the fuel line almost immediately. I'm also going to replace the zip ties on the exhaust pipe in case it's leaking and not building enough pressure to pressurize the tank. Thanks for the tip.
mattster197 That could be the problem. I shortened the fuel line to the tank, and used small zip ties on all the joints, and the problem has went away. It runs great, now all i need to do is get the carb needles set properly. She is running a little fat on the HSN, so I'm going to work on getting it set after I get back from vacation.
does it work without the blue boot? i cleaned out my old traxxas carb, but the boot rippled as it hasnt been used in almost 9 years and it's quite hard to find the parts for it in my country (indonesia) anw this vid helped me alot in cleaning out my old T-maxx so hyped to get it back working!
hi my low speed needle is 6 1/2 turns out but in my manual it says 3 1/2 for break in, but when I put it to 3 1/2 turns out it just cuts out as soon as I touch the throttle. its only a cheap GO 18 engine out of a ftx carnage, and it is broken in, it's had about 1 1/2 liters through it.
+Gary Leopard Adjust it to where it preforms. Weather Altitude and fuel have tremendous influence on how an engine runs. For your setup 6 1/2 isn't out of the norm.
very helpful video I watched your video and changed my carburetor of revo 3.3 I have some issue with my revo after the 1 3/4 turns of idea screw there is no any gap, very hard to blow fuel doesn't pass to fuel line and it won't start any help will be highly appreciate
very few carb cleaners will hurt plastic, almost all ive used have never had an issue with plastic... however BRAKE cleaner will surely damage plastic... best bet would be throttle body cleaner, as it is made specifically to be safe around sensors, and a lot of sensors are plastic
I have a 0.28 engine that just wont start, or run after i start it. it will only run on the fuel i primed into it. Now i know i have a different carburetor to you, but your guide was very helpful. I hope that re building the carb will heal and cleaning in. Note the first time i did this, i changed the fuel inlet to a more accessible position, so i will have to change it back, hope i can get it running tomorrow, again thank you for your video. :D
