trophy truggy 4.6 break in
12-26-2016, 03:01 AM
#1
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trophy truggy 4.6 break in
Hi im fairly new to the nitro scene and im currently in the process of breaking in a trophy truggy 4.6. Currently on the 3rd tank after running in on idle for 2 tanks. All needles are at base settings, i seem to have a problem where the car just idles really fast making the car take off unless i turn the throttle trim on the remote right down. Could anyone explain how i make the car idle steady with the throttle trim in central pisition. Also in the manual it states the lsn doesnt need tuning but on various videos/forums they state the lsn gets tuned after the hsn ?? Any advice appreciated
12-26-2016, 05:33 AM
#2
It sounds like the linkage isn't closing the throttle valve (slide valve) when the throttle is in the neutral position. Using the throttle trim to drop the idle is a confirmation of this. So adjust the throttle linkage such that the throttle is closed against the idle stop when the servo is neutral and trims are centered.
Both needles get adjusted (or should be) every time the engine is run - that is if the ambient temp or humidity is fairly different from when the engine ran last. Set your high speed first for max performance, then back off rich 1/8-1/4 turn. Set the idle mixture so it just barely loads up at idle after idling for 10-15 seconds. You will know your idle is set right if you hit the throttle after say 15 seconds and the engine studders a little bit. If you set it leaner, it will probably run hot. If the idle hangs after a WOT pass (holds a high rpm setting for a few moments after letting off the throttle), the high speed is lean.
Also, you should never idle an ABC engine - they don't last all that long when treated that way. Fire it up, heat it up to 180-220F, and drive it around. Kinda easy at first (ease into and off the throttle smoothly) ramping it up (and leaning it down) slowly.
Both needles get adjusted (or should be) every time the engine is run - that is if the ambient temp or humidity is fairly different from when the engine ran last. Set your high speed first for max performance, then back off rich 1/8-1/4 turn. Set the idle mixture so it just barely loads up at idle after idling for 10-15 seconds. You will know your idle is set right if you hit the throttle after say 15 seconds and the engine studders a little bit. If you set it leaner, it will probably run hot. If the idle hangs after a WOT pass (holds a high rpm setting for a few moments after letting off the throttle), the high speed is lean.
Also, you should never idle an ABC engine - they don't last all that long when treated that way. Fire it up, heat it up to 180-220F, and drive it around. Kinda easy at first (ease into and off the throttle smoothly) ramping it up (and leaning it down) slowly.
Last edited by 1QwkSport2.5r; 12-26-2016 at 05:35 AM.
12-26-2016, 05:52 AM
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Just finished break in procedure, started the tune process by leaning the high speed, noticed after coming off full throttle it sounded mad is that the to lean tone ?? Managed to get idle down using idle needle but ill have a look closely at the linkage after dinner. Ohh and do you still get fuel out of exhaust when tuned right or is that a too rich sign. Beginner lool
12-26-2016, 06:29 AM
#4
Just finished break in procedure, started the tune process by leaning the high speed, noticed after coming off full throttle it sounded mad is that the to lean tone ?? Managed to get idle down using idle needle but ill have a look closely at the linkage after dinner. Ohh and do you still get fuel out of exhaust when tuned right or is that a too rich sign. Beginner lool
If by sounding "mad" you mean the rpm hung for a moment before dropping, then yes it may be too lean. When you make adjustments to the needle valves, do so in small increments.
Do NOT use the idle mixture needle to lower your idle! As you mentioned previously - you could lower the idle with your trim knob. So that means your linkage is maladjusted. You will get your settings all messed up if you don't follow the proper procedures. If the carb is closed tight against the idle stop (linkage doesn't close carb further with more servo movement) and idle is still high, adjust the idle stop. This screw is on side of the carb near the top that runs at a bit of an angle towards the slide valve. Usually it's close to the crankcase. Backing this screw OUT lowers the idle speed. Adjusting the idle stop WILL require adjustment of the idle mixture needle (in the throttle slide valve) richer. Closing the idle gap leans the fuel mixture.
You should have oil coming from the exhaust at all times. Only when the fuel mixture is sloppy rich will you possibly get raw fuel droplets to come from the exhaust, though car engines usually do
not tolerate fuel mixture that rich. Likely you saw oil out of the exhaust - this is a good thing.
12-26-2016, 09:57 AM
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Just come back in from having a play, been leaning with the hsn and havent messed with the lsn. Ill get better overtime i suppose. When i lift car off the ground it goes full rpms, havent messed with linkage but im adjusting rpms with the idle stop screw (1 that makes gap bigger/smaller) and trim on remote. Once the hsn is tuned correct what is the purpose of lsn, does it improve throttle. Only thing what's annoying now is getting it just too sit ticking over with no throttle at all, having to hold brake on.
Last edited by pro8186; 12-26-2016 at 09:59 AM.
12-26-2016, 10:06 AM
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You have given me quite alot of advice, reading back your replys i forget to richen the lsn after backing out the idle screw. Back out tomorrow for more practice. Ohh merry Christmas buddy 😆
12-26-2016, 10:26 AM
#7
It might not be a bad idea to do a little reading in your owners manual and maybe on the Internet as there is a ton of tuning into posted about the subject. The way you're tuning your carburetor is going to cause a lot of grief for you later.
12-27-2016, 11:10 AM
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#update#
Been out with the car today, set idle gap to 1.5mm with brake applied and throttle trim in netutral position. Warmed up engine with hairdryer and fired first attempt. High idle !!! Had several laps, got engine up to temp and tuned hsn clockwise a few turns then 1 turn counter with a nice trail of smoke. Very quick !!! Thats when i managed to get it to idle with a steady forward & backward motion by leaning the lsn by doing a pinch test as it wasnt quiting untill 8 secs. Does not stall either when brake applied. Can u see anywhere im going wrong ?? Oh and i tried adjusting the linkage but the servo was engaging making a noise so i backed off again.
Been out with the car today, set idle gap to 1.5mm with brake applied and throttle trim in netutral position. Warmed up engine with hairdryer and fired first attempt. High idle !!! Had several laps, got engine up to temp and tuned hsn clockwise a few turns then 1 turn counter with a nice trail of smoke. Very quick !!! Thats when i managed to get it to idle with a steady forward & backward motion by leaning the lsn by doing a pinch test as it wasnt quiting untill 8 secs. Does not stall either when brake applied. Can u see anywhere im going wrong ?? Oh and i tried adjusting the linkage but the servo was engaging making a noise so i backed off again.
Last edited by pro8186; 12-27-2016 at 11:15 AM.
