First i have a ds650 2001 completly rebuilt motor from crank up. has fmf pipe. thats all, however i have an over heating issue, i have manualy wired the fan so it runs all the time does not help ! i have tried taking out the thermestat dont help eather ,but thurm stat does open properly and i reinstalled it. i just tried engine ice today filled the system with it and still over heats. Yes my water pump works not sure how much pressure it makes but it works. i am out of ideas please help. could my jetting be so far off that it over heats?? also my oil breather tube shoots a mist of oil while its running any ideas with that would be a big help? thanks

 

you have a head gasket problem, check your head to make sure its not warped

 

is this for the oil spraying out or for the over heating. im asking because when i rebuilt the motor i used all new gaskets so im wondering. thanks for the help

 

How do you know it is overheating, do you have a temp gauge installed?

I ask because many assume its overheated when the expansion tank overflows, but fact is a leaking head gasket causes combustion pressure to enter the coolant system and force coolant from expansion tank simulating overheat. I know its a new gasket, but if there is a problem with warp, or if install was not properly torqued, or if gasket was somehow damaged, well you get the drift...

If it is actually overheating, are you sure you have it filled? This is tricky for some, as you must warm the bike up with the radiator cap removed, and once you see flow down the hole from thermostat opening and start seeing bubbles gurgle up you have to top it off repeatedly til its full and no more gurgle, cause you won't get all the air out and get it full until the thermostat is open and there is flow. it will never ever draw coolant from the expansion tank to top itself off unless ALL air is removed from system. even with thermostat removed, it takes flow to get all the air pruged from all the recesses of the cylinder and head, it must be topped off running.
fyi running without thermostat will NOT reduce temp, it only allows the coolant to spend LESS time in the radiator which is the opposite of helping.

 

yes i have installed a temp gauge in the hole for the fan switch sence the fan is wired on all the time yes that is the hot side of the therm, wanted to know if the stupid light was right, and it is. light comes on about 210 and temp goes up till 235 when coolent starts boiling. I was looking at it today and didnot see any light threw the radatior, it took me 20 mins with the pressure washer to get all the mud out, so i am going to try that and see what happends. thanks for all the help, i am also going to do a leak down test and see if i get bubbles in the coolent. any other ideas would help.

 

I wouldn't worry about the leak down test, the head gasket aint gonna cause an overheat, it just causes the situtation i described, sounds like you found your problem a dirty radiator aint gonna cool anything. be light and careful not to bend all the aluminum cooing fins over with a pressure washer and if some get bent you can get a tool to straighten them its like a tiny plastic comb auto parts stores have them

 

A leakdown is a mighty fine idea - a bad head gasket seal (depending on degree of failure) may not be evident by watching the expansion tank.

It also gives you the ability to verify the condition of all 4 valves that have been subjected to improper cooling due to your overheating issue ... as well as piston ring integrity.

 

I mean I do agree a leakdown test is a perfectly fine idea, it just has nothing to do with the overheat problem

 

Was atv over heating before rebuild job? what cause the engine to fell making it need an rebuild job? or an upgrade?

 

to be honest im not sure i baught it with a screwed rod and a messed up pistion and head. the over heating could have caused it but i dont think so. i have not gotten to put it back together yet working so much and it is 96 deg with 100 per cent humidaty so i will up date when i get it back together.