Motocross action overheating cure

[David411]

I read in a later issue of MXA that they had found a simple way of curing the overheating problem in an earlier issue? Does anyone know? thanks ??

[John407]

I subscribe to MXA and have a '04 KXF250. I don't remember any one single simple cure. Drilling holes in the plastic louvers (in front of the rads), boysen impellor and 2 piece cover, higher pressure rad cap, water wetter I can't think of anything else.

[kawy]

if you have a KX250f and it's over heating, go to your local Kawy dealer and tell them you want i high pressure rad cap..it's from Kdx 650 (or something like that)..i can't remember it's either yours is a 1.3 and you need a 1.6...or the other way around..the dealer will know

[David411]

what does that cap do?

[KXMike]

what does that cap do?

i think on the 2004 kx250f there is a 1.1? rad. cap. you can buy the 1.6 rad cap and when you put it on it takes more force from the coolant for it to overflow and overheat your bike.

[David411]

thank you guys/girls for all the help and advice.

[tonydeli7]

if you put the radiators from 05 kxf it won't overheat

[tnt250]

That's an expensive fix, especially considering that the boyesen impeller and cover do the same thing.

[stezlaki]

That's an expensive fix, especially considering that the boyesen impeller and cover do the same thing.

Really?????? Ours has both the bigger radiators and the Boyesen stuff and still pukes out coolant if you stop for more than a millisecond!!

Oh, and a 1.6 cap. Oh, and Carbon Fiber things to force in more air. Oh, and water wetter.

[tnt250]

There must be something wrong, mine idles for 5 mins without puking.

[stezlaki]

There must be something wrong, mine idles for 5 mins without puking.

Could be...........I know they have a reputation for heat, but this thing is kinda rediculous. Thing is, it seems to run pretty good, and doesn't overheat as long as it's being ridden on the track, but if you stop long enough to tell someone your going back to the truck (well, maybe a little longer, but not much), you can bet there will be a trail of coolant behind when you pull away. We're not talking an excessive amount of time here..........my Yamaha will undergo much longer durations under identical variables w/out ever puking. If you were to let the RMZ idle 5 minutes, I doubt there would be any coolant left.

[pooman]

i had 04 rmz 250, changed the rad cap to 1.6 and i have the 05 kxf 250 and have not had both of them puke on me, i do abit of track but mostly trail and enduros.

im sure if i hade to let her stand for 10-15min she would puke....

[tonydeli7]

i just have put 05 rads and it doesn't overheat at all...i think of putting the boyesen impeller... if it is cooler it is better!

[tnt250]

The cooler it runs, the more power you get. Dunno what to tell you stezlaki, what kind of coolant are you running? Are you sure the jetting is right? Also, what kind of fuel? Believe it or not, fuel can change temps 40 degrees either way quite easily.

[gonzo]

Go get a KX65 radiator cap. It's a 1.8. It adds more pressure to the system. Makes it flow better and cools faster. I put one on my 450 and it really helped out alot.

[cdntanker]

I'm beginning to question the overheating myth associated with these bikes, my wife rides and 04 RMZ250, and we were at a MX school last Saturday in smoking hot temps, 35degrees celsius with humidex well over 40, and she could sit idling waiting her turn to run at a jump or corner for the school and that bike never dropped an ounce of coolant. Even my Yammie was running hotter and two CRFs began dumping coolant. She has the Boyeson cover and impeller and runs 2 ounces of water wetter along with the std coolant mix and she's never had a problem?

Maybe this is something that varies bike to bike and we're just lucky but so far this hasnt been an issue for us.

Sure would like to see Suzuki/Kawi formally address this issue, if this really is such a wide spread problem, then they should step up to the plate and address it like they did for the CDI, backfire screen and hotstart cable.

Hopefully you can get yours sorted out, they shouldnt be that finicky, you need to be able to sit at idle at the gate without having to worry about the bike puking fluid.

[2thmperzdad]

If your RMZ is puking coolant, I'll bet that the head gasket is cooked! Mine was. I would loose up to two inches of coolant each time the bike was ridden. I spent $100 on engine ice before I got the problem resolved. I put the 1.6 cap and Boyesen pump kit on, but it didn't fix the problem. Fortunately, I met Bret at www.icwbikestands.com and he had the cure. The biggest problem with the RMZ / KXF is circulation. Bret extended my radiators, but more importantly installed a different piping system that allows for better flow. I haven't had an issue with overheating or puking since, and the bike is raced in 90+ degree weather. Give Bret a call, I am sure he can hook you up too!

[stezlaki]

................ stezlaki, what kind of coolant are you running?

Had the water wetter in there.........now trying some engine ice.

Are you sure the jetting is right?

Actually, no.........we recently got this bike second hand and, as far as I know (according to previous owner) jetting is stock. I've been doing searches on here about jetting for these bikes and it looks like if it is stock, I need to at least go up to a 42 PJ. I may just get a JD kit for it...............not sure. It does have a Yoshi pipe on it, which, as best I can tell supposedly doesn't require any jetting changes. I e-mailed them (Yoshi) to verify, but haven't heard back. We won't be riding for a week or so, so I hope to straighten some of that out. The bike does run good, though, without bogging or popping, for whatever that's worth.

Actually, one question I have regarding jetting has to do with the backfire screen. I'm assuming that these bikes had one from factory (ours doesn't.......has the twin air setup.......we got it that way).........and I read on one of my searches that main jet should be increased one step if screen removed. Does that sound right?

Also, what kind of fuel?

High octane pump gas.........92/93 octane depending on where we get fuel.

[tnt250]

With a pipe and the backfire screen removed, you definetely need to richen up the jetting. 42 pj sounds right, i'd then go from there. You'll have to adjust the fuel screw. With premium, you should be fine although some gas stations have worse quality gas than others so try to get the best that you can (shell, exxon, mobil,ammoco). But the lean condition in the jetting (which you no doubt have) will definetely cause overheating problems.

[mxracer22122]

yeah when i bought my 04 RMZ250 i just had them put a high pressure cap on it before i took it home and i havent had problems since.