disapearing coolant

02 WR426F Since I've had the bike I have contiuously had to add coolant every time I ride for any length of time usually about a half a pint or so. I havent noticed any leaks anywhere I have check the bike by letting it run on the stand with a fan blowing in the radiator to keep it from over heating and have found no leaks. Do you think it might be a head gasket,how can I tell without tearing the engine down or can I ? The bike runs Great no problems. :thumbsup:

Check to see if it is getting into your oil! :devil: Otherwise you are evaporating it and have a hot running engine which is also not good. :thumbsup:

WR426 are running so lean when stock that many riders don't even need the hot start to start the bike even when it is really hot.... A lean engine runs hotter. Check this out. I agree with what was said. If you have no coolant in your oil, you are evaporating it and it means that your bike runs too hot. You may have no gasket problem at present but it might come in this case... What is your jetting and what temp and altitude do you run? I'm not a jetting king but some guys here could help you with that for sure

Guys I've been through the carb and the jetting is perfect according to the plug. I have great flow through the radiators. I have leak tested it (again) :thumbsup: and no leaks. I just purchased some Water Wetter by Redline, I'm gonna try this to see if it helps. Its supposed to releave the surface tention of the water giving it better heat disapation properties.

The coolant has to be going somewhere. If it's evaporating it's making steam out of your overflow tube. If you have a WR with the catch tank you should loose NO coolant unless it is going into your crankcase or your cumbustion chamber and out the tailpipe. Sometimes the water pump seal dribbles a little.

If the catch tank is removed then the best you can hope for is it's getting past a weak radiator cap and out the overflow tube.

Presure test your cap or replace it one from another bike and see what happens.

That coolant will not just disapear like that.

From what I've seen if it was a head gasket and the coolant was leaking into the cylinder you would be getting some white smoke out the exhaust. Could be a waterpump seal. I'd check my oil. Those are the only two things I've run into in the past.

Most bike shops will have a radiator pressure tester. It's a special radiator cap that you fit to the bike which allows you to pressureise the cooling system, and read any leakage on a guage.

Guys this problem is really testing my knowledge. There is no water in the oil plug looks great the coolant dose somtimes disapear from the overlow tank, the cap hold 12lbs of preasure and the cooling system will hold 21lbs with no problem I think theres a coolant grimlin steeling my coolant. :thumbsup:

any bubbles appear when you run the bike with the radiator cap off? Unlikely that coolant 'leaks' into the combustion chamber. 12psi in the water jacket, and a few thousand psi in the chamber. Stupid question. Is it possible you had an air lock in the system somewhere? If this happens it would appear that you are losing coolant, but it would just be getting sucked into the radiator to replace the air. Next step it to fit a temp trobe in the radiator hose and check the running temp.

Well I finaly decided to tear down the top end in an effort to find the problem, here is what I found. On the tear down the headbolt nearest the exhaust was loose I'd say less than 15ft lbs, no signs of burn through on the head, cylinder or gasket. How ever I checked the head with a straight edge and it was warped. So I very carefully blocked the head with a 4X6x1 peice of machined aluminum stock and 100 grit emery cloth checking it with a flat piece of glass and a feeler gauge till it was perfectly flat. I also did some bowl blending and contour work on the ports leaving the intake with a cutter finish and polishing the exhaust and boy what a differance it made especialy with the yz cam settings. Here is the bad part, yesterday I carried it to the track for the first time since the mods and no coolant loss but how ever with the new found power and a rear tire that is half worn, lots of wheel spin. After a couple of 5 lap outings I desided to let it rip and see what kind of lap time I could get. On a jump that can be doubled or tripled I can usualy triple fairly easily I had too much wheel spin and ended up landing on the face of the trip landing casing the bike really hard wich resulted in a terrible crash, the worst I have had, two hyper extended wrist 3 broken ribs dilocated hip, but no worries I'll be back on as soon as I can stand it. Oh the bike came out with only some scratches, broken clutch lever and bent and rotated brake lever.

ohh nasty! Get well soon.

:thumbsup: Ouch!!

It hurt just reading that post! :devil: Get well soon.

I had a similar coolant issue a while ago. never used any coolant for the 1st 4 months I had the bike, then over a few rides it lost the contents of the overflow and about an inch out of the radiator. Flushed the system, put in some new coolant and bled the air out. Hasn't used a drop since then :thumbsup: It's going harder than ever before, so I'll just leave it alone for now.

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