trx 2.5 engine idle hanging up
10-19-2004, 08:55 PM
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trx 2.5 engine idle hanging up
i have a tmaxx with a trx2.5 engine and i was wondering, after i tune the high speed to good performance and not overheating and i go to the low speed when i turn it in a 1/16 at a time eventually the engine will hang up(idleing real fast) and then finally idle down. i am pretty sure that i need to riching the low speed 1/16 or until it will not hang up. also is a nova head a good cooling head. thanks.
10-19-2004, 09:47 PM
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RE: trx 2.5 engine idle hanging up
well are u tuning for performance or by temp? you want to tune for perfornce then check temp try that. is this ur first trx 2.5? if so it may take a few gallons to learn how to tune thats what happened with me.
10-19-2004, 11:14 PM
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RE: trx 2.5 engine idle hanging up
yeah this is the first trx 2.5, i was very unhappy until i worked on it for about a month and learned how to tune. i love the motor it is very reliable and if tuned right it should last a long time. about the tuning, i personally tune for a safe performance, i don't go overboard trying to squeeze every last bit of power out of my engine, my motor runs safely at about 240-250f with good power. the only thing was the engine hanging up when the low speed needle is to lean, i am just wondering if that is the cut off point on leaning the lsn. Also i was wondering does alot of other slidevalve engines do the same thing by hanging up if the low speed is set to lean. i tuned a friends savage 25 and never had that problem, or is it just with the trx 2.5. alot of people hate the motor, but the truth is u have to be very careful on adjusting the thing as i learned out the hard way.
10-20-2004, 09:36 AM
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RE: trx 2.5 engine idle hanging up
The engine is great ,it's that carb. that can be a problem . I would set the L/S at flush and work on the H/S make sure that the seals are in good shape and the linkages are set right, RED
10-20-2004, 06:13 PM
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RE: trx 2.5 engine idle hanging up
i would just go to stock settings and tune from there. Here is how i tune my truck personally. i start with the HSN and then get the perforance i desire, then when its at that i check the temprature and if its in a good range leave it there. even if im running 210 i keep it there becuse i got good perforance and its running good. if its running good why mess with the LSN?
10-20-2004, 06:46 PM
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RE: trx 2.5 engine idle hanging up
Im in the process of tuning my first nitro motor right now.. it is also a trx2.5 Mine hangs up just like yours does..
hopefully I can pick up a temp gauge, and a friend of mine can help me tune it properly this sunday
hopefully I can pick up a temp gauge, and a friend of mine can help me tune it properly this sunday
10-20-2004, 11:59 PM
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RE: trx 2.5 engine idle hanging up
i called the tech line at traxxas and the guy said that if the engine is hanging up to richen the lsn 1/16 and run the truck a few high speed runs to get any excess fuel out of the carb, and then check it if it still hangs up than richen it another 1/16 until it idles down with out hanging up. Also if u ever go and readjust the high speed needle because of it overheating always set the lsn back to default, which is flush with the slide and then if u have messed with the idle screw make sure that it is 1mm open and then readjust the high speed and then on to the low speed. The reason i say this is because by leaning out the hsn u cut the fuel flow and this makes the lsn leaner which on the trx 2.5 causes it to idle fast and then dies because it starves it for fuel, this is why they say to alway tune the hsn first because everything else revolves around this screw.
10-21-2004, 07:55 AM
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RE: trx 2.5 engine idle hanging up
ORIGINAL: nitroman99
i called the tech line at traxxas and the guy said that if the engine is hanging up to richen the lsn 1/16 and run the truck a few high speed runs to get any excess fuel out of the carb, and then check it if it still hangs up than richen it another 1/16 until it idles down with out hanging up. Also if u ever go and readjust the high speed needle because of it overheating always set the lsn back to default, which is flush with the slide and then if u have messed with the idle screw make sure that it is 1mm open and then readjust the high speed and then on to the low speed. The reason i say this is because by leaning out the hsn u cut the fuel flow and this makes the lsn leaner which on the trx 2.5 causes it to idle fast and then dies because it starves it for fuel, this is why they say to alway tune the hsn first because everything else revolves around this screw.
i called the tech line at traxxas and the guy said that if the engine is hanging up to richen the lsn 1/16 and run the truck a few high speed runs to get any excess fuel out of the carb, and then check it if it still hangs up than richen it another 1/16 until it idles down with out hanging up. Also if u ever go and readjust the high speed needle because of it overheating always set the lsn back to default, which is flush with the slide and then if u have messed with the idle screw make sure that it is 1mm open and then readjust the high speed and then on to the low speed. The reason i say this is because by leaning out the hsn u cut the fuel flow and this makes the lsn leaner which on the trx 2.5 causes it to idle fast and then dies because it starves it for fuel, this is why they say to alway tune the hsn first because everything else revolves around this screw.
"flush with the slide" do you mean reset it so that the head of the screw is even with the piece around it? I dont know what the slide you speak of is..
10-21-2004, 11:16 PM
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RE: trx 2.5 engine idle hanging up
yes flush with the piece around the screw. also u can screw it in all the way and then back it off 1 3/4 turns out and this is also right on with the default setting on the lsn. as u lean out the lsn after the high speed is set, lean it out slowly until u get good take off, or until it starts to hang up and then back it off a hair until it idles down smoothly, also when the engine is cold or just cranked up it will idle quicker so don't make any adjustments until it is up to temp or just do a few high speed runs.
