Any way to keep the KDX cool?

kevinkdx

Member
Mar 25, 2001
481
0
I have a 93 KDX 250 and on an 85 degree day after I play around in the sand for awhile it will spit coolant over the overflow tube and onto the ground. Is there anything that will keep my bike running cooler? Does Water Wetter work? any suggestions are well appreciated.
 

kmx125r

~SPONSOR~
May 23, 2000
127
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Hi Kevin,

I, too, have a 1993 KDX250 and just 30 minutes ago I topped off my radiators, bled any air out of the water jacket (through the bleed screw on the head) and then rode around in the yard for 15 minutes...

Before long I too was spitting coolant all over my driveway. So I'm looking for any help with this issue too.

Recently, I was having trouble with a surging idle, someone suggested that maybe I was loosing coolant and the engine was getting hot which led to the surging. I think they may be right.

Does anyone with a KDX250 have any idea what coolant level is maintained in their radiators under normal operating? Does it run a little low? Can I hook up an overflow bottle like the 200 has and would that help?

Help us out!

Thanks.
 

Jackpiner57

~SPONSOR~
Aug 11, 2002
356
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Do you guys need new radiator caps? They might not be holding the pressure back because the spring is worn out?

Are they overheating?
 

jaguar

~SPONSOR~
Jul 29, 2000
1,507
82
South America
cooling basics: put in a radiator cleaner (acidic) to clean out the mineral buildup that's there as a result of dufusses who don't know to only use distilled water (which don't have minerals). Put in 50/50 distilled water and radiator fluid. straighten out all radiator fins with a knife. change the jetting to be richer but not too rich. take off the ignition cover and see if theres black oil there. If so then its there as a result of a failing crank seal which will cause the bike to run leaner and therefore hotter. They normally last around 2 years.
 

Y2Z

~SPONSOR~
Apr 6, 2002
411
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what do u mean my surging idle, because my bike does that too i think(92 KDX) and everyone tells me my carb needs to be jetted...
 

beefking

~SPONSOR~
Nov 12, 2002
150
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Make sure you don't have any air leaks around the carb boots either-while running spray carb. cleaner on the boots (WD40 would actually be easier on the rubber) and if the engine responds at all you have a leak. The rad. cap could be suspect too, maybe the rubber gasket is worn out/cracked, it is an older bike. You could try a higher atmosphere cap (stock is 1.1 or 1.2 i think?) like what the KX500 runs, 1.9 atm. That would prevent losing fluid, but the bike would still be hot.

Make sure you're not jetted too lean (pilot circuit primarily-if you're on a lean main jet all the time you will most likely be moving fast, cooling the bike). Once you have all that stuff figured out, try running Engine Ice in the rads, it really does keep the bike cooler than regular anti-freeze. Technically, distilled water would keep the bike cooler- but it would also corrode the rads/motor up alot faster.

Good luck.
 
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kevinkdx

Member
Mar 25, 2001
481
0
well i have new crank seals and bearings, the coolant is 50/50 with distilled water and it is only half a year old. The jetting is right on and a few of the fins are bent on the rad. Not sure what it could be. Oh yeah and the Rad cap i had trouble with before so it is also brand new. I also have a brand new cylinder and head with gasket so those are not the causes. Just looking for something to stay cooler... Water Wetter????? does it work?
 

Robcolo

Member
Jan 28, 2002
342
0
Out & up here in the thin air of CO & Utah, most of our 220s overheat & boil. We tried EVERYTHING, hi-pressure caps, water wetter, not climbing sand dunes, etc and nothing worked ---until ---www.evanscooling.com
Get the NPG+ formula and you'll never again boil over or lose a drop of coolant. Follow their directions explicitly - getting every last drop of water out of your system before adding their product is the secret. I don't even check my coolant level any more.
 

skipro3

Mod Ban
Dec 14, 2002
902
0
I agree with Robcolo. My KDX220 still runs hotter than a KDX200 side-by-side, but with the Evans installed correctly, it never boils over or looses any coolant. I've even removed my overflow tank which now helps air flow. Has your KDX always been hot or is this something new?
 

outrgus

Member
Jan 15, 2003
95
0
i also use evans coolant and it works great, bike never overheats and also you don't have to worry about corrosion in your rads. i also think my top end last longer because of the lower heat.
 

kevinkdx

Member
Mar 25, 2001
481
0
This has been an ongoing problem but it has been intensified by my paddle tire which makes me want to play more than usual.
 

Robcolo

Member
Jan 28, 2002
342
0
"Playing" in sand probably puts a heavier load on an engine than any other type of riding -- and much of the time you're not going fast enough to push the needed amounts of air through the rads. Many guys will rejet just for sand [richer on main & needle] as that helps keep things cooler.
 

kmx125r

~SPONSOR~
May 23, 2000
127
0
Hey All,

Got a new radiator cap today (13 psi), topped off my coolant (as per the manual), and took a 20 miles ride. I wasn't too far into the ride when I noticed that coolant was coming out the overflow tube and spilling on to the ground.

After the ride, I let the bike cool down and added coolant to the same level as before... I added 175ml of coolant. So since my system holds 1100ml, that means I lost 16% of my coolant. I suspect it would have continued to consume coolant if I had ridden further/longer, but I can't confirm that...

Further thoughts?
 

motometal

LIFETIME SPONSOR
Sep 3, 2001
2,680
3
Further thoughts...you may want to verify that the bike is in fact overheating.  I know you said the head gasket was ok, but maybe it's worth another look.  Maybe this just means feeling the cylinder with your hand and comparing it to a similar bike, etc.  If the head gasket is bad, it will leak because the combustion pressure is way higher than what the rad cap can hold.

I ran an optional (from Kawasaki) higher pressure cap on a KX100 years ago and it helped, just a thought, may be the hot ticket for some of you sand diggers out there.
 

motometal

LIFETIME SPONSOR
Sep 3, 2001
2,680
3
Jaguar, you are right in theory, but in practice this testing technique works better in cars in in bikes.  There is so much circulation and turbulance even with normal operation, i'm not sure if you could tell a difference, especially if it was a small leak. It doesn't take but a pinhole leak in the gasket to cause coolant to drip out.
 

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