weird idle, help please?
02-10-2013, 03:44 AM
#26
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RE: weird idle, help please?
ORIGINAL: JohnP2
I was the one who suggested he fatten his gap, merely to rule out having too small of a gap (and we ALL see that too often). However. this has been a FASCINATING thread concerning idle gap I'm spendin my Saturday night talking idle gap on an Internet forum. I am proudly hooked! ;-) We always hear .5mm can be too small and 1.0mm too big, so I agree that sounds ideal. .7mm sounds about right (at worst the best starting point). In thinking about it, most of my best tunes had ~.7mm gap.
Anthoop (and I LOVE your avatar by the way!) you posed some great questions. If i'm to deduce this thread, it's that you work your mixture around the idle-stop gap. i.e., that is what you start with and go from there. Only assume this is the first entry way of air, and you stabilize that and work in the fule mixture.
I was the one who suggested he fatten his gap, merely to rule out having too small of a gap (and we ALL see that too often). However. this has been a FASCINATING thread concerning idle gap I'm spendin my Saturday night talking idle gap on an Internet forum. I am proudly hooked! ;-) We always hear .5mm can be too small and 1.0mm too big, so I agree that sounds ideal. .7mm sounds about right (at worst the best starting point). In thinking about it, most of my best tunes had ~.7mm gap.
Anthoop (and I LOVE your avatar by the way!) you posed some great questions. If i'm to deduce this thread, it's that you work your mixture around the idle-stop gap. i.e., that is what you start with and go from there. Only assume this is the first entry way of air, and you stabilize that and work in the fule mixture.
For me it is not a case of adjust the gap to X and that is where it stays, most important is to get the amount of fuel correct for the amount of air, then adjust the gap for the correct idle speed to prevent the clutch engaging. In the video (OP) the engine has an uneven idle, pointing to an incorrect mixture, this can be fixed by altering the amount of fuel or air....whether we adjust air or fuel does not matter...if (when we have the correct mixture) the idle speed is too high/low it can be adjusted with the idle screw.
I think Neal and I are reading from the same page...just using different methods to get the same end result.
02-10-2013, 05:57 AM
#27
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RE: weird idle, help please?
ORIGINAL: Anthoop
It is nice to have a natter about a hobby you love with like minded poeple.
For me it is not a case of adjust the gap to X and that is where it stays, most important is to get the amount of fuel correct for the amount of air, then adjust the gap for the correct idle speed to prevent the clutch engaging. In the video (OP) the engine has an uneven idle, pointing to an incorrect mixture, this can be fixed by altering the amount of fuel or air....whether we adjust air or fuel does not matter...if (when we have the correct mixture) the idle speed is too high/low it can be adjusted with the idle screw.
I think Neal and I are reading from the same page...just using different methods to get the same end result.
ORIGINAL: JohnP2
I was the one who suggested he fatten his gap, merely to rule out having too small of a gap (and we ALL see that too often). However. this has been a FASCINATING thread concerning idle gap I'm spendin my Saturday night talking idle gap on an Internet forum. I am proudly hooked! ;-) We always hear .5mm can be too small and 1.0mm too big, so I agree that sounds ideal. .7mm sounds about right (at worst the best starting point). In thinking about it, most of my best tunes had ~.7mm gap.
Anthoop (and I LOVE your avatar by the way!) you posed some great questions. If i'm to deduce this thread, it's that you work your mixture around the idle-stop gap. i.e., that is what you start with and go from there. Only assume this is the first entry way of air, and you stabilize that and work in the fule mixture.
I was the one who suggested he fatten his gap, merely to rule out having too small of a gap (and we ALL see that too often). However. this has been a FASCINATING thread concerning idle gap I'm spendin my Saturday night talking idle gap on an Internet forum. I am proudly hooked! ;-) We always hear .5mm can be too small and 1.0mm too big, so I agree that sounds ideal. .7mm sounds about right (at worst the best starting point). In thinking about it, most of my best tunes had ~.7mm gap.
Anthoop (and I LOVE your avatar by the way!) you posed some great questions. If i'm to deduce this thread, it's that you work your mixture around the idle-stop gap. i.e., that is what you start with and go from there. Only assume this is the first entry way of air, and you stabilize that and work in the fule mixture.
For me it is not a case of adjust the gap to X and that is where it stays, most important is to get the amount of fuel correct for the amount of air, then adjust the gap for the correct idle speed to prevent the clutch engaging. In the video (OP) the engine has an uneven idle, pointing to an incorrect mixture, this can be fixed by altering the amount of fuel or air....whether we adjust air or fuel does not matter...if (when we have the correct mixture) the idle speed is too high/low it can be adjusted with the idle screw.
I think Neal and I are reading from the same page...just using different methods to get the same end result.
I am talking a much more refined tune then just having the idle low enough that the clutch isn't engaging......In racing we have to be far more particular with our tune then that, prety much everyone at the track automatically has their idle low enough not to engage the clutch, that's quite basic really ........unfortunately You can have the idle low enough to not engage the clutch, but still so high it causes all sorts of tuning and driving issues..........As I say most guys set their idles way too high, and for bashing you can get away with it, but with racing you cannot.....My idle will range from 0.3 mm -0.6 mm ................ I cringe when I read these forums and guys are giving people advice of setting the idle to 1-1.5 mm , and cringe even more when they suggest running sport fuel with more oil then nitro.... talk about setting someone up for immanent failure LOL !
02-10-2013, 11:49 AM
#28
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RE: weird idle, help please?
I could point you to far more cringe-worthy answers to various questions on other forums I frequent.
Most of the people asking tuning advice here are not racing and are running RTR engines, my advice to those people is start from the manufacturers settings and work from there....although we know how dubious those settings can be sometimes:-
Slide gap= 0.25-0.5 ... http://www.racing-cars.com/images/Te...anual/fp10.jpg
Slide gap 1.0 ... http://www.cmldistribution.co.uk/dia...%20_3-Port.pdf
Both pretty similar engines but very different base settings....they both work with those settings.
At the end of the day (after adjustment) the hope is that the needle will be in the correct position pertaining to the slide gap....but those settings will at least get it running.
Most of the people asking tuning advice here are not racing and are running RTR engines, my advice to those people is start from the manufacturers settings and work from there....although we know how dubious those settings can be sometimes:-
Slide gap= 0.25-0.5 ... http://www.racing-cars.com/images/Te...anual/fp10.jpg
Slide gap 1.0 ... http://www.cmldistribution.co.uk/dia...%20_3-Port.pdf
Both pretty similar engines but very different base settings....they both work with those settings.
At the end of the day (after adjustment) the hope is that the needle will be in the correct position pertaining to the slide gap....but those settings will at least get it running.
02-11-2013, 04:42 AM
#29
Senior Member
RE: weird idle, help please?
ORIGINAL: Anthoop
I could point you to far more cringe-worthy answers to various questions on other forums I frequent.
Most of the people asking tuning advice here are not racing and are running RTR engines, my advice to those people is start from the manufacturers settings and work from there....although we know how dubious those settings can be sometimes:-
Slide gap= 0.25-0.5 ... http://www.racing-cars.com/images/Te...anual/fp10.jpg
Slide gap 1.0 ... http://www.cmldistribution.co.uk/dia...%20_3-Port.pdf
Both pretty similar engines but very different base settings....they both work with those settings.
At the end of the day (after adjustment) the hope is that the needle will be in the correct position pertaining to the slide gap....but those settings will at least get it running.
I could point you to far more cringe-worthy answers to various questions on other forums I frequent.
Most of the people asking tuning advice here are not racing and are running RTR engines, my advice to those people is start from the manufacturers settings and work from there....although we know how dubious those settings can be sometimes:-
Slide gap= 0.25-0.5 ... http://www.racing-cars.com/images/Te...anual/fp10.jpg
Slide gap 1.0 ... http://www.cmldistribution.co.uk/dia...%20_3-Port.pdf
Both pretty similar engines but very different base settings....they both work with those settings.
At the end of the day (after adjustment) the hope is that the needle will be in the correct position pertaining to the slide gap....but those settings will at least get it running.
This is exactly why nitro can be such a challenge for people starting, as even the manufactures writing the instructions don't even know the proper way to tune and setup their own engines properly.........talk about confusing people with terrible advice..........
At the end of the day, bashing or racing their is a proper way to tune a engine and a improper way to tune a engine......tuning around a large idle gap causes all sorts of of issues............
02-11-2013, 10:50 AM
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RE: weird idle, help please?
ORIGINAL: supertib
tuning around a large idle gap causes all sorts of of issues............
tuning around a large idle gap causes all sorts of of issues............
02-11-2013, 05:01 PM
#31
RE: weird idle, help please?
ORIGINAL: Anthoop
The only reason I can see for that is people using the LSN to adjust the idle speed.
ORIGINAL: supertib
tuning around a large idle gap causes all sorts of of issues............
tuning around a large idle gap causes all sorts of of issues............
Is there ever a reason to tune LSN for idle? Not talking about the ability to idle.....but idle performance....if that makes sense.
Thanks!
02-11-2013, 10:57 PM
#32
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RE: weird idle, help please?
Adjusting the LSN on a nitro engine is a must do on all types of 2 cycle engines. Most all the engines leave the factory with the LSN and HSN set very rich. They do that to protect the engine when breaking it in, as the engine loosens up you will need to lean the both high and air fuels settings. Do not touch the idle screw till after the engine is fully broke in. That way the engine has settled into it's, and the idle has stabilized enough that you can turn the screw counter clock wise to lower the idle rpm some. You will want turn it down just to where the clutch is not try to grab and roll off. that will get you in the ball park so you can tune the low side needle. Most cases you will want to screw it in an hour at a time let set for around 8 seconds or so to stabilize the air fuel mixture. after you get it right the idle will be running to fast again and will need to be adjusted. Test the car and see if it responds from idle to mid rpm, if all is well then start you HSN by leaning it in one hour at a time till it leans over some. Then back it out to where it was the best setting before it got lean. Now it should hold a tune for a good long time, provided you use the same fuel every time you run the engine. I hope this helps you out some. I wish I could help you out more? anyway this is what works for me that's why I pass it on. All the best Arless
02-12-2013, 05:01 AM
#33
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RE: weird idle, help please?
you can get away with using the LSN to adjust idle speed much easier if your tuning a short needle carb...on a long needle carb your best to never adjust idle by the LSN.....Short needle and long needle tune differently and require different strategies....
02-12-2013, 09:51 AM
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RE: weird idle, help please?
ORIGINAL: JohnP2
Is there ever a reason to tune LSN for idle? Not talking about the ability to idle.....but idle performance....if that makes sense.
Thanks!
Is there ever a reason to tune LSN for idle? Not talking about the ability to idle.....but idle performance....if that makes sense.
Thanks!
So, it is yes and no (from me) to the question I think you are asking.
02-13-2013, 07:18 PM
#36
RE: weird idle, help please?
I spent an hour yesterday jacking with the tune on my OS .25xz.. I think I'm happy with it, and will post a video of it on the trackso youguys can tell me where to improve. I'm definitely learning there is a difference between a "tune", and a "race-tune."
One of the items I'm working on is RPM decrease after mid+ throttle. What is the rule of thumb for this? I've heard/read a breadth of suggestions, but the majority seem to state it should decrease to idle 1-2 seconds after letting off WOT.
I don't know the answer so am trying to learn what I can on the subject. Thanks!
One of the items I'm working on is RPM decrease after mid+ throttle. What is the rule of thumb for this? I've heard/read a breadth of suggestions, but the majority seem to state it should decrease to idle 1-2 seconds after letting off WOT.
I don't know the answer so am trying to learn what I can on the subject. Thanks!
02-13-2013, 07:38 PM
#37
Senior Member
RE: weird idle, help please?
ORIGINAL: JohnP2
I spent an hour yesterday jacking with the tune on my OS .25xz.. I think I'm happy with it, and will post a video of it on the track so you guys can tell me where to improve. I'm definitely learning there is a difference between a ''tune'', and a ''race-tune.''
One of the items I'm working on is RPM decrease after mid+ throttle. What is the rule of thumb for this? I've heard/read a breadth of suggestions, but the majority seem to state it should decrease to idle 1-2 seconds after letting off WOT.
I don't know the answer so am trying to learn what I can on the subject. Thanks!
I spent an hour yesterday jacking with the tune on my OS .25xz.. I think I'm happy with it, and will post a video of it on the track so you guys can tell me where to improve. I'm definitely learning there is a difference between a ''tune'', and a ''race-tune.''
One of the items I'm working on is RPM decrease after mid+ throttle. What is the rule of thumb for this? I've heard/read a breadth of suggestions, but the majority seem to state it should decrease to idle 1-2 seconds after letting off WOT.
I don't know the answer so am trying to learn what I can on the subject. Thanks!
what glowplug are you using ? and what fuel ?
02-13-2013, 08:04 PM
#39
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RE: weird idle, help please?
ORIGINAL: JohnP2
Still running the P3 (I have the P4 but did not put it in). Losi Nitrotane 30%
Still running the P3 (I have the P4 but did not put it in). Losi Nitrotane 30%
as I told you before, a P3 is a very hot plug, you will struggle to tune out the high ringy ping ping till you use a cooler plug.........
02-13-2013, 08:46 PM
#40
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RE: weird idle, help please?
I have read thru most of this discusion and there is an old school way to adjust the LSN needle and I also discuss some glow plugs.
http://www.xenonproject.com/tuning-y...gine-a-10.html
The old school way of adusting an LSN is called a pinch test. The engine should only run for a few seconds after pinching the fuel line.
- [*]Step 2. Low-Speed Fuel Mixture Adjustment
- The low speed mixture adjustment is performed only after the high speed needle has been correctly adjusted. The easiest way to adjust the low speed mixture is by doing the "pinch" test. The valve is located where the throttle arm pivots.
[/list]
“Pinch” Test
Having set the high speed needle correctly, take the RC vehicle and pinch the fuel line going into the carburetor. The engine should run for about 2-3 seconds, speed up, and die.
If the engine runs longer than 3 seconds, give the low speed needle a 1/16 turn clockwise. Run the vehicle again and retest. Repeat as necessary.
If the test results in the engine dying immediately, without speeding up, richen the low speed needle by giving it 1/8 turn counter clockwise. Run the vehicle again and retest. Repeat as necessary.
Once the low speed needle is correctly adjusted, the engine throttle should respond very quickly. It is now time to adjust the idle speed.
Now we can get into Glow plugs while there is no perfect solution for these in the winter time HOT plugs will keep an engine running longer because in the cold air temps you require richer fuel mixtures, In the summer time Meduim Heat Glow plugs will last longer in most fuels between 10 to 30 % nitro. Why because the Filiment is thicker. For racing engines some suggest cold plugs when running 30% or over nitro content. Problem with Cold plugs they will flame out if the idle screw is not set right on the edge of clutch engagement..
This chart indicates the direction in which you should adjust the fuel mixture when faced with changing conditions. It assumes the engine is currently well tuned. You could face any combination of conditions listed in this chart. Knowing how to adjust the fuel mixture is a crucial part of operating and maintaining your RC vehicle. Higher Air Pressure Lean 
Lower Air Pressure Rich 
Higher Humidity Lean Lower Humidity Rich Higher Barometric Pressure Rich Lower Barometric Pressure Lean Higher Altitude Lean Lower Altitude Rich Higher Nitro Content Rich Lower Nitro Content Lean Higher Oil Content Lean Lower Oil Content Rich Hotter Glow Plug Rich Cooler Glow Plug Lean [Back To Top]
We hope you found this information useful and enjoyed our easy to use tutorial guide. For more tutorials, how-to guides, FAQs, and much more, please visit our Learning Center at XenonProject.com.
