KX60 Idle Speed

Have a KX60, which is idling too slow to a stall.  The idle speed screw in completely in. I can fool it by tightening up the throttle cable but something is not right.  The screw seems to be contacting the slide and it is open ever so slight.  The screw doesn't seem to be worn and I tried without the spring to see if that waws preventing it from screwing in but the screw is bottomed.  Gas was a bit old but don't think thats the issue.  If I had an air leak it should run faster correct? 


Background:  Did a bottom end rebuild quite a while back (over a year), did very little riding up until a few weeks ago.  After the rebuild I returned to 32:1 mix had been 40:1 (possible reason for the crank failure) I must have left a bit of fuel in the tank and it worked past the petcock and gummed up the carb to where it wouldnt start.  After a half baked cleaning it ran good but did have a bog from idle when wacking the throttle. Last week I took the carb off pulled the jets and idle screw out and gave it a proper cleanout.  Got rid of the bog but noticed the low idle as soon as the engine warmed.



I had an issue like this once. The loop on the plunger isn't centered in the lever mechanism to the float. Check the float and plunger for proper opperation.

So did you completely clean the carb or not? If not, start by cleaning the carb, fully disassemble and soak anything that's not rubber or plastic (or remove the rubber/plastic bits first) in parts cleaner for 15 minutes, at least.

Drain, blow out all orifices with compressed air and reassemble.


The KX60 carb is so incredibly simple, there's no excuse not to fully strip and soak the carb every time.


Yes, at a minimum, run 32:1. I run 28.5:1 (because this is half way between 32:1 and 25:1, so one gallon 32:1 and one gallon 25:1).


Drain the tank, use what ever was in the tank to power your lawn mower and start over with fresh pre-mix. With the idle screw all the way in, the bike should be idling around 2500 RPM.


Yes, you could still have an intake leak, but start the diagnostic process with a clean carb and fresh gas.

First cleaning was just a bowl removal and carb cleaner in the orifices.  It started, had a low bog off idle only when you whacked the throttle in neutral, kid rode that afternoon without issue.  I striped it the second time cleaned with carb cleaner, pipe cleaners, nylon brushes and air.  After that cleaning the bog was gone.  Went riding and after fully warmed my son noticed a problem, which was the slow idle.  I screwed the idle down then adjusted the cable so we could continue riding.  Cleaned again same way and also used a fine wire for the tiny holes in the needle jet. When it started it idled very slow with the screw all the way in, but I wouldn't say it was fully warmed up.  Tonight's cleaning, was a strip, soaking in cleaner for 15 minutes followed by rinse and air. Fresh gas, cleaned air filter, tried with no filter, new plug. Same thing after the third cleaning.  Let it sit for 4-5 minutes and it idled very slow but did stay running. Took the filter off, no change. I think as it fully warms up it will continue to die.  If I backed the idle screw out 1/2 a turn it would die so fully screwed in is nowhere near 2200 rpm.


Regarding kdub’s suggestion I can’t see how the float is going to affect idle speed, if that was messed up wouldn’t it be more an issue at higher speeds. Or spilling fuel out. the overfllow.


The Clymer manual shows no rubber O-rings on the carb, only a gasket on the fuel valve seat and the gasket between the bowl and carb so I didn’t leave any O rings out.

Air leak would actually help things out wouldn’t it? Or show as a problem at other engine speeds.  As I try to think this through it seems like it’s not getting enough air. It doesn’t seem to be loading up with fuel.  Initially I figured the little holes on the intake side of the carb throat might be plugged.  The cleanings should have cleared anything out.  Ran a copper wire into them and didn’t feel anything. The engine speed doesn’t hang up when I blip the throttle; it comes right down to the low idle.


Was thinking of taking the air box and boot off and messing with the intake of the carb with my hand to see if that makes any changes.

How did the choke look? It sounds to me like it's getting a bit too much fuel on the slow speed circuit. This could be the choke or you may have damaged the pilot jet when you poked wires through it. You should only do that as an absolute last resort, I had one jet this past weekend that after soaking for an hour still was plugged. Instead of throwing it out, I pushed a wire through it. But that's only after deciding that it was practically beyond repair.

What's your jetting and elevation?

The loop came off the lever to the float, and then got pinned under the lever.  Ran super weird for a while.  With the way a carb works it should have been cutting the fuel off to soon, which would run the pilot nearly dry.  Then you screw the idle all the way in wich raises the slide / needle just a little.  Letting just a little of that circuit to start working.

Pilot is a 30 which according to Clymer is stock (bikes a 96) the main I can't really read well possible it's a 200.  The needle I'll assume stock too, clip is up two from bottom or down one from middle (stock)so the needle is raised one, I think that's the only adjustment I made from when I got it.  I did replace the choke mechanism 2 years back. Looks good visually no pitting, gum or discoloration.


Since I have it apart I'll give it a longer soak paying special attention to the choke orifices. If the local shop has the pilot I'll pick up another stock size as it worked well in the past and the next larger.


Elevation is 800'


Floats are operational, did not check level. But I think the level is ok fine other wise I'd be leaking fuel or it would die out at higher speeds due to fuel starvation.

I soaked the carb again for a bit longer.  Replaced the jet with a stock size from the dealer.  It appeared to be used possibly from a coffee can of misc jets.  I wouldn't say it's fixed but bike will remain running even after about 10 minutes of warm up. I was able to turn the idle screw out about 1/2 turn from all in, before it would get too slow and die.  I'll see how it goes after a ride.  I'm thinking I will still order a new stock jet and one fatter.  I did run without the filter and airbox.  Placing my finger over the (as your looking at it) left side small hole would slow the idle and kill the engine, no change on the right side hole.  I thought they should both affect the idle circuit.

"Small hole"? You mean the ones on the mouth of the carb, right? There isn't any small holes on the side of the carb that affect anything is there? (shouldn't be, KX60 carb has no mixture screw, however, other VM24? 26? I forget the exact model number do have them. Like from a KX65 or early RM60s).

Don't worry about a jet that shows age. It will work the same as long as the orifice size is correct.


I have another thought. On the top of the carb where the slide drops in, does that have a rubber gasket? What about on the throttle cable? If either one is missing, it could be letting air into the carb causing it to run leaner than it should especially at idle.

Edited by Smacaroni

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