220 overheating

[dougjc]

Here is some background first. My bike (2003 220) is all stock except for some extra holes in the air box cover and the rejetting described. I ride at sea level to 200-500 feet max. My plugs had been very sooty so I changed the stock 145 main jet to a 142 and replaced the stock 42 pilot jet to a 40. I also moved the needle jet from the 3rd to 1st position. I run my mixture at about 35:1. No, I have not been able to do the plug chop yet.

During a very tight woods section of an enduro yesterday, I stopped and noticed that coolant was boiling out of the vent tube. Most of the riding was in 1st gear. I also thought I heard some knocking or pinging at higher RPM's (maybe to lean?). The coolant resevoir was empty and I could not see any fluid in the radiator although it might be half full or so. My plugs still look dark brown so it doesnt seem overly lean. Could the move to the 1st needle jet clip position be too much and cause the bike to run too lean/overheat?

 

[McRider]

The needle clip position doesn't have any effect until you are above 3/4 throttle, so I don't think that would be the problem in a tight woods section. If it was a hot day and you were not getting much air through the radiators, it may have been unavoidable. It has happened to me on a long slow mountain climb.

 

[dougjc]

It was only 80-82, so I don't think it was the weather.

 

[DENNY]

1. Do you have radiator guards?
2. Is your carb stock other than jetting?
3. Did you check the radiator before you road? Not the overflow!


If you are riding Michaux in Sept. look me up and I'll show you what I've done to my 220. It's my third KDX and I have them figured out for where you live. Just ask any SPER member where Denny Mann is.

 

[nectar]

....don't worry about it....mine would leak radiator fluid from the res. all the time when riding in tight trails....and everytime I check the actual raditor it was full...you said you check the radiator?....did you try to full it with anti-freeze?...cause it's really quite hard to see if its empty just by looking into the radiator....anyways good luck with it....

 

[dougjc]

Denny,

1. Do you have radiator guards? No, well yes, the stock white plastic ones
2. Is your carb stock other than jetting? Yes
3. Did you check the radiator before you road? Not the overflow! Yes, the radiator was full (99% sure I checked prior to race)


Unfortunately, I will be out of town and cannot make the Michaux. It would be great to hear more about your bike and/or meet up some other time.

Doug

 

[BRush]

If you were looking in your radiator and could not see any fluid, that would be problem #1 (and likely the only problem). What coolant/mix are you using now?

Besides the other suggestions given, Look at the radiator fins. Are they mashed flat from impacts or tree branches? If so you may have to dismount the radiators and use a small blade or screwdriver to reopen the air passages. Tedious works, but it pays off.

Other coolants:
1) Redline Water Wetter and distilled water. I’ve used this with great success to cure boil over. Just be sure to change it out when the weather begins to cool down (no anti freeze protection).

2) No personal experience, but some others have posted positive results with Evans (non-H20) coolant.

 

[kdx633]

your bike is 2003, did you ride tight woods stuff before any jetting changes? If so did you boil over?Are you sure it was full in the first place?Just like suspension linkage lube you can't always be sure the factory got it right.Dealer should check this during prep (you know that three-hundred dollar added fee for opening the box).And last the air bleed screw on top of cylinder was that purged.trying not to jump all over everywhere but I had similar problem on mine first time out.these are steps taken when refilling coolant and the problem never came back.

 

[rice1825]

I have had the exact same issues happen a few times (4-5 times) in the tight woods, and I specifically checked to make sure the radiator was topped off before each of those rides, and after the ride all the anti-freeze had disappeared from the overflow, and radiator looked empty too. Mine is an 03 220 as well. I tried changing to engine ice, and upon refilling the system I used the air screw to bleed the system. Still have the same problems. As of right now, I check the radiator before every ride, and even during rides and enduro's. If low, I refill with my camel back until the race is over. Then it is home to flush the system again and refill. I am thinking about taking the overflow off all together, as I read a few people say this solved their problem. Until I hear another solution, I will be just refilling and keeping an eye on it. I don't know what else might be the problem. My oil isn't milky, and the bike doesn't have any other problems. It seems to be running good.

 

[DENNY]

With the stock carb I doubt this is a lean condition. The best advise I could give is watch the Jeff Fredette Maintenance video. Jeff removes the overflow tank and builds an air dam that forces air through the radiators. I did this back in 92 and with every KDX since without any over heating problems.

 

[KAY DEE EXER]

Could you give me some info about that air dam and how to do it please.

 

[outrgus]

USE EVANS COOLANT AND YOU WILL NEVER HAVE ANOTHER PROBLEM AGAIN. THIS STUFF IS AWSOME.

 

[DENNY]

It's on the video but basically it is using duct tape on the sides of the radiators. So all of the air goes through the radiator and not around them. I have logged over 12000 miles on 3 different KDX motorcycles without over heating.