simple nitro tuning question

[flyp]

My idle seems high, it rolls just slightly, anything less it stalls....and after running awhile, when I brake hard and idle for more than 5 seconds, it stalls and is difficult to restart?

 

[dougc]

Your idle speed is to high. Take off your air filter then trun on your radio and turn the idle speed till it is about 2mm from closing

 

[robriguez]

Friend of mine recent;y had the same problem. It turned out to be two issues.

1) His idle speed was set too high. Follow Dougc suggestion and adjust the idle set screw.
2) The spring on his two shoe clutch came undone. The clutch shoes were draggin on the inside of the bell even at idle. When he would brake hard at high speed his engine would sputter and sometimes die.

I would check both of these just to be safe.

 

[wdavidhicks]

It's also possible that your low speed needle is set too rich. Have you done the fuel line pinch test?

 

[jon2]

First off what type of engine is it? Second, 2mm may be a bit too much. All you need for the opening is 1mm. you should check your brake set up as you may be having an incorrect idle or LSN settle set up.

 

[kwong2001]

Originally posted by flyp
My idle seems high, it rolls just slightly, anything less it stalls....and after running awhile, when I brake hard and idle for more than 5 seconds, it stalls and is difficult to restart?

Could be a bunch of things. Idle mixture could be too rich or too lean.

Engine is probably overheating (I assume you don't have a temp gun). That also can make it harder to restart. And give you a crappy idle.

You could be running too rich on the HSN and when you go from WOT to idle, some unburned fuel is still in the engine and floods it.

Could be the clutch engaging like robriguez said.


Oh yeah, personally, I dont adjust the idle by visually seeing how much the carb is open, I play it by ear and listen to the engine at idle. It's more accurate IMO.


This is what i'd do, some people might not agree. Rework the LSN and keep the idle just a tad on the high side. Then with your temp gun (if you have one), rework the HSN so your engine is running at anywhere from 170-200 degrees depending on your engine. Then bring down the idle to where the clutch isn't engaging. Should be pretty tuned

Now if you don't have a temp gun. Rework the LSN using the pinch test, if it dies 1-2 seconds after you pinch the fuel line then it's set just about right. Pay attention to how much smoke is coming out of the exhaust when you go WOT. It should be pretty linear, meaning the same amount of smoke is coming out every time no matter what RPM you're at. If more smoke comes out, lean the HSN a little, if less comes out, richen is up a tad. Generally though, at idle, you won't see a whole lot of smoke like when you're driving around.

my .02

 

[flyp]

thanks for the suggests. I don't have the LSN so that seems to be the real trouble. I got everything running great except it still rolls at the lowest possible idle setting. I checked the clutch and seems kinda of shoddy and noticed the higher end Kyoshos (i have the gs-15r) have a better clutch so I ordered one, a cheaper option until I upgrade the so an engine with a LSN.

but I have another question, can I just get a better carb, seems Kyosho doesn't sell one seperatly for the gs-15r, but will any other brands fit?

 

[RobH]

welcome to rcnt!

I don't know a whole lot about carbs that don't have a LSN. All I can offer is this small quote for Ron Paris:

For sport engines which lack a low-speed needle, the idle-stop screw is the only method of adjusting the engine’s idle speed. For these engines, simply turn the idle-screw clockwise to increase idle speed, and counterclockwise to reduce the idle speed.

As far as changing the carb goes, yes you can change them, but typically you end up with a carb from another engine transplanted on yours. Knowing which of the carbs out there will fit your engine is anyone's guess as each carb is typically designed for on particular engine. Hence, there is no reason to publish the measurements.

If you have a Local Hobby Shop (LHS), someone there may be able to look at it and give you some advice.

If it were my R/C, I'd probably go buy a good engine like an OS or something that is easy to tune. *shrug*

Good Luck and once again welcome,
Rob