Overheating?

[RZMike]

I've been reading through the overheating threads for the last 2 hours. Got some good ideas and tips, however, after reading all that I'm not sure overheating is my problem.

I have a 03 KDX 220 that I bought from the original owner 5 months ago. It's been running like a champ until this past weekend. We were riding in the woods. Alot of 2nd. and 3rd gear stuff. Air temp was 65. It ran fine for about an hour then when rolling on the throttle to accelerate hard it would die. If I got off the throttle quick enough it would recover and keep going. It's done this before when fouling a plug, so I changed the plug - didn't help this time. Fearing a more serious problem I parked the bike. When I got home I washed the bike. I always ride it up and down the driveway a few times after washing and it ran just fine. So I figured I must have overheated it. After reading all the threads, I'm not so sure now. It didn't boil over and I haven't lost any coolant. Does this sound like a overheating symptom?


Here's the specs on my KDX. Motor & pipe stock. Airbox has three large holes drilled in the lid. Jetting - 145 main, 42 pilot, needle clip in the middle slot. Looking a the plug, it appears a little rich. Also has the occasional spooge from the pipe/silencer joint that I interpret as a rich condition.

This is my first KDX, so any help would be appreciated.

 

[KDXruss]

IMHO, It dosen't sound like overheating. It sounds like 'loading up' and fouled plug.
When I first got my 220 it was rich with stock jetting. Riding it slow, through tight nasty stuff ( small throttle opening) always made it load up and eventually foul the plug.
So I jetted down and I also run a hotter plug. It is a racing machine after all you have to keep it hot and cleared out. :cool:

 

[crhines]

Doesn't sound like overheating to me. When a bike overheats the radiator generally boils over, it runs raspy, and you can smell the motor running hot.

I have found that if I'm off the throttle for a while, it will load up a bit; example, if I'm descending down a long hill, it may take a couple of seconds for the carb to clear out when I get back on the throttle. If I were to hammer the throttle in this situation I think it may cut out.

By the way, I have a 99' 220 with a Procircuit Pipe, air box mods, FRP porting, and stock carb. My carb is 38 pilot, 145 main, and needle on top clip (leanest) at sea level. I testing multiple jetting combos and found that a bigger pilot just created more spooge.

 

[RZMike]

Thanks for the replies. When it ran fine after cooling off for a couple hours, I jumped to the overheating conclusion. Now, I have to agree that it doesn't sound like overheating.

I'll try playing with the jetting some. Maybe it is just loading up. I also read some interesting discussion about the float level. I haven't ever checked that - might be a little high.

Thanks again for the help....

 

[76GMC1500]

Might be a little low, too. Sounds like the bike is running out of gas and then slowly filling up the bowl while it sits.

 

[RZMike]

Might be a little low, too. Sounds like the bike is running out of gas and then slowly filling up the bowl while it sits.

Yes, that was my very first impression out on the trail. I checked the gas cap vent line and even pulled the fuel line from the carb, but couldn't find anything wrong.

Hopefully, I'm going to have time tonight to pull the carb off and have a look.

 

[76GMC1500]

You may have gas in the tank, but that does not mean its filling the carburetor float bowl at an acceptable rate.

 

[RZMike]

You may have gas in the tank, but that does not mean its filling the carburetor float bowl at an acceptable rate.

Well, I've pulled the carb off to have a look. Nothing appears out of order. The inside in clean as a whistle. Taking 76GMC1500's hint, I connected the fuel line to the carb leaving the float bowl off and turned the gas on. Looks like it's getting plenty of fuel.

Put the carb back on and took it for a ride (I've got about 1 mile of single track around the house). After approx. 30 min of riding it started acting up again. Same characteristics as in my first post. If I keep trying to ride it, the problem progresses to the point it will only run for about 5 seconds then die. Sounds like it's starving for fuel as 76GMC1500 suggested, but don't see any evidence of that. I pulled the carb again while it was hot and tried the whole fuel flow test again with the float bowl off - nothing.

What about ignition? Do the KDX's have any history of the CDI's failing? My Yamaha RZ350 had simular symtoms when it's CDI went.