Bike over heating in traffic

Last fall before I put my bike (85 Maxim X) away I was experiencing a overheating problem when sitting in traffic. Once the bike actually over heated and dumped a bunch of coolant. The problem is that the days this happened it was relatively cool (5c / 40F) and the bike wasn't running that long, 1st traffic light on the way home from work, (2km - 1 1/4 miles). The time the bike dumped coolant I watched the gauge hit the red line and heard the fan kick in. It's almost like the coolant is not circulating. I'm pretty sure the theromostat is ok but am going to take it out and check it. Is there anything I can check in the water pump? Any suggestions?

Thanks

--
Regards;
85 XJ750XN (Maxim X)

 

motorcycles don't hold a lot of fluid. i think my ninja 600 only held 2.5 quarts. so, sitting at a light won't take long to heat up. at what point on the gauge did y our fan come on. is it in the normal range or higher. it might be the fan switch kick on too late. did the bike cool down as you rolled down the road. if it stayed hot that would be a sign of plugged radiator. OR closed thermostat. a closed thermostat would heat up faster then a plugged radiator. you can pull out thermostat. put in a pan of water and let the water boil. using a thermometer read what temp the water gets when the thermostat opens up. i beleive most bikes are rated at 160.

it could be a bad waterpump not circulating very good. or not spinning at all. could also be something as simple as a radiator cap not holding pressure anymore. you should see water circulating with the cap off though indicating waterpump is doing SOMETHING.

measure the temp difference between the two radiator hoses. water going into the radiator will be hotter then water coming back out. with the fan running the outgoing hose into engine will be even MORE cooler.

if you have a harborfreight close by. they sell handheld laser thermometers fairly cheap. i have the 1500 degree. works really good. although not for use for a pan of boiling water. as your measuring 2 heat sources. the hot water AND the bottom of th pan.

 

If the thermostat is good and was full of fluid (with no air pockets) can only be 2 things. 1st have you noticed it running warmer and warmer over a period of time (months) would be radiator. 2nd I am not saying it couldn't be the water pump but they usually don't just quit. If you havn't pulled the thermostat yet start it up let it warm up see it the radiator is getting hot easy way to check see if the upper hose is getting hot close to radiator if it is. thermostat is opening. feel the cooling fins on the radiator make sure its warm everywhere and no cold spots if it is probably not the radiator. There is a possibility that its the thermostat even if it is opening could be sticking on occasion . To be honest i would replace it then you know its not that the rest of the parts are a lot more money. There is 1 other possibility could have a bad head gasket or cracked head. to find this problem you need to take it to someone with a sniffer Its a detector that is used to detect exhaust gas in the radiator. you have to remove the radiator cap to check it but it only takes a few min

 

Water-cooled? Whats that?

 

cracked head or gasket usually mixes oil with the water though. and usually puts out TONS of water vapor out the exhaust.

since he lost water just sitting at a light though. that can't be good for the engine. not that it would do harm on the first shot if not gotten toooo hot.

 

not necessarily true. If you have a crack large enough to pass coolant yes it will either get in the oil or go out the exhaust but a hairline crack will pressurize the cooling system and blow coolant out of the overflow when the engine gets warm. I have replaced them before. Cars are really bad about it if you crack the cap they are ok. But would not recommend that on a bike

 

Thanks for all the replies. I haven't noticed any water vapor coming from the exhaust or oil in the coolant. The bike ran fine in traffic all summer when the temps were much higher. Normally it had to be pretty hot out and I had to be sitting for a while in slow traffic. The gauge would creep up to the boarder of the red on the gauge then the fan would kick in and the temp would drop back. But the last two times as soon as I stopped at a light the temp started to climb. The fan kicked on right when it was suppose too but the bike dropped maybe a 1/2 cup of coolant. As soon as I got moving the temp dropped back to less than 1/2 the gauge and was ok. Is it possible to over fill the rad? Could the system get an air lock? I had noticed that the reservoir was low and added coolant. After this is when I had the trouble.

Because of where the bike is stored starting it is not an option. I'm doing some work on it so I will pull the thermo and do the boiling water test to see if is opening up.

Thanks for your help. I'll keep you posted.

 

Can a shop do a pressure test on a bike rad the same as they do with a car?

 

anyone with a sniffer can check it. It only takes a few sec all you do is pull the rad cap off stick the hose in the top and sniff it. Hopefully it passes its not an everyday occurrence and usually it has to run pretty hot to cause it but better safe then sorry Have you checked the t-stat yet?

 

since he said the bike cooled down as he started rolling. that would indicate everything is working just fine.

it could be just a bad radiator cap not holding pressure. but water does expand as it heats up. you probably just lost the overflow if everything was plum full.

keep an eye on the reservoir. there's probably nothing wrong. if you find it is heating up faster then normal. specially when the weather starts warming up. a new thermostat and radiator cap would be good insurance.

if it does get hot again. you could try revving the motor a little to see if it comes back down. that would be a good indication that the waterpump isn't circulating very good at an idle. but may be nothing to worry about.

do a google search and see if others have had the same problem.

 

Or it could have a bad fan switch. I think i would replace the t-stat just for piece of mind. I had 1 stick on a boat it opened up thought everything was ok. Took it out 4-5 times then it stuck again when the alarm went off it was to late and lost the motor .Was a pain going 2 miles on a trolling motor

 

I don't know much about the details of a water cooled bike...but it seems like the fan should switch on well before the bike is about to overheat? Is the fan generally off on the maxim x until the water temp reaches 180 deg or more?

 

i've had 2 honda v65 magnas and one ninja 600. none of which the fan came on untill the gauge ALMOST hits the red.

it would be nice if motorcycles used numbers instead of bars. don't know about the rest of y ou all but i'd prefer an actual temp. just for the sake of knowing degrees instead of bars.

 

If that's the case, then I'm not entirely sure MaxFly has a problem. If the needle ALMOST hit the red and the fan kicked on, but didn't ACTUALLY hit the red, then the bike didn't overheat.

The overflow is a natural result of a fully filled radiator reaching such a high temp.

Am I wrong?

 

I should clarify, my assumption is that the gauge is less accurate than the temp sensor for the fan. So even if the needle is barely in the red that doesn't mean the temp is too high. High, yes, but not overheat high.

 

The fan is coming on right when it is suppose to and always did. My issue really is the bike heated up way faster that it normally did all summer when it was a lot hotter out. Snowwy66, thanks for the tip on the rad cap. Now that you mention it I remember someone else having pretty much the same problem and it turned out to be the rad cap. When I get a chance I will test the thermo and add a new rad cap. When the bike is back on the road I will post an update and let you know if the issue still persists.

 

This post is so old I don't know if you are still on here, but I'm having the exact same symptoms with my 700 Maxim-x and wonder what you found to be the problem. I stopped at the Yamaha shop and the mechanic said he doesn't have a clue but would love to have me spend a couple thousand dollars there for him to figure it out.....eventually.