c00lguy

I need help with the idle gap. I've always been told to do a .5mm to 1mm gap. When you look at the idle gap through the carburetor, are you suppose to look at it straight down? The reason I ask is because let's say you do a 1mm gap. If you look into the carb at an angle, that 1mm gap is actually bigger. How are you guys looking into the carb? Straight down or at an angle. Thanks!

Kyosho KE21 and KE25 engines.

MotoGod

iTrader: (118)

Straight down, pull out your restrictor as well.

c00lguy

Thanks!

Hoese37

iTrader: (5)

Easy way to do it is get a paper clip that is about .8mm and slide it in the carb throat with your restrictor out. Now adjust the idle gap until the slide just touches the clip, and there is very little resistance when you pull on the clip.

Apco1

iTrader: (2)

So you do in fact take out the restrictor to set the gap? Wouldn't the gap disappear once you put the restrictor back in?

YANMAN

iTrader: (41)

Yes and yes.

MotoGod

iTrader: (118)

Yeah you do, otherwise the idle gap would be quite a bit bigger than what you set it to with the restrictor in. Yes it will disappear from view with the restrictor in, but rest assured it's still there ;-)

Hoese37

iTrader: (5)

It does visually disappear, but the restrictor doesn't fit tight against the slide so a gap is still there.

c00lguy

Ok now I get it! I think I was setting my Gap wrong the whole time LOL. I think thats how I managed to blow my previous KE25. I had gap set to 1mm with the restrictor on it. It was hard to hold a tune and I think my LSN was a bit too rich.

Once the Idle is set to .8mm to 1mm, next step is to tune the LSN correct? And when tuning the LSN, do you also need to adjust the idle again to keep the idling down?

I am about to do another engine break-in for a KE25. To my understanding... for the first 5 tanks, I should leave the A, B, and C needles at factory correct?
My question though is once the engine has been broken in, how do I adjust the HSN and LSN? Meaning, once the engine is broken in, do I completely turn the HSN clockwise, then do 2 full turns counter clockwise and tune from there? Same concept with LSN...fully close the screw then do 2 full turns open and start to tune from there? The idle gap, I'm assuming I just need to set it at .8mm to 1mm like normal.

Thanks guys for the help! I want to get this right this time. I've gone through about 8 engines over the last 6 months. I keep blowing them and I think its because I have my idle gap and LSN all mucked up! What is the general rule as far as the LSN -5-6 seconds for the pinch test? Where on the fuel line do I do the actual pinch because I know the closer to the gas tank you go, the more time it will take to stall the engine. Thanks again.

Hoese37

iTrader: (5)

Idle gap will stay the same, and you will tune your final idle speed by the LSN. When you start tuning after break in, go from the break in settings.

stoney452

iTrader: (1)

I never mess with the idle gap I just warm my engine up and then set it by sound then adjust the lsn if I need to.

Ccolemugen

iTrader: (10)

Look in the "the engine tuning bible" section in the off-road engines forum. It's a sticky at the top of the page. This was very helpful to me when I first started to get the "feel" of engine tuning. It's very dificult to get general answers because every engine tunes differently. This will help you understand exactly what you are doing to the engines fuel flow when your adjusting the needles. You might also want to look at "the engine break-in bible as well. It would be hard for me to find the time to correctly break-in 8 engines in 6 months.

vandalzzz

easy way to set 0.5mm gap :
Take a piece of twisted pair used for computer networks, split it, pick one of the wires, remove isolation. According to specs copper wire itself should be 0.4-0.6mm, usually it is exactly 0.5mm, and it's safe to recheck with calipers.

MotoGod

iTrader: (118)

Paper clip is easier to source for most non-IT people ;-) usually they measure @ 0.7mm

nv529

iTrader: (53)

Numbered drill bits work great for setting idle gap too.

#76 = .5mm
#73 = .6mm
#70 = .7mm