XJ 700 X - Overheating, Fan Not Kicking On

Hi Everyone,

Thanks for any thoughts you may have on this.

Here is what I am observing:
- Temp gauge needle does move when key is turned on.
- As bike runs, temp gauge does not move.
- Fan never kicks on.
- Has boiled over through the fill tank before I knew there was a problem.

Here is what I think:
- Temp sender is either gunked up or has failed. Is this common, or should I look elsewhere for the temp gauge not moving/working right?
- I haven't tested the fan with a direct current. Is the fan tied to the temp gauge? That is, does it kick-on based on certain level from the gauge?
- Thermostat could be stuck or gunked up. I haven't pulled it.

Before I started ripping things apart, I wanted to see if anyone has seen something similar and could point me to a most likely candidate first. Also, it does look like the water pump has been worked on or rebuilt as evidenced by a homemade silicone gasket. What is the best way to see if it is working correctly.

Thanks for any experience that can be shared around the X's cooling system.

 

When working properly, the fan on a Maxim-X will kick in when the temperature gauge needle enters the red zone on the gauge. A properly functioning fan starts late then, but will cool the bike very quickly.

I've read somewhere (probably here, www.maxim-x.com) that bad or dirty connections on the thermoswitch (located in the vicinity of the thermostat housing behind the ignition coils under the gas tank) can cause false low temperature readings and late fan start. I presume a badly compromised connection would cause total gauge malfunction.

However, as you seem to infer, that wouldn't cause the bike to overheat (at least not until you reached the red zone and the fan didn't kick in) so the thermostat and/or water pump may also be involved.

In terms of checking the water pump, there is one ugly way of doing it. Pretend you are doing a radiator flush. There are several small drain openings along the Maxim-X coolant system pathway (for a real radiator flush) that you could open. Start the engine, rev it up a little (the water pump I think is gear driven) and open a drain. If the pump is running, it should develop enough pressure for the radiator fluid to shoot out much faster than a normal gravitational drain and the engine reving should affect the discharge flow velocity. You might want to have a hose handy for a quick refill or ongoing replenish.

For the thermostat, I'm going out on a limb here but I heard somewhere you could "watch" whether a thermostat is working properly by placing a cool closed one in a pot of near boiling water. If working properly you should be able to observe it open. Gotta admit though I've never tried it.

Artie(RT)

 

Thanks Artie!

I had some time to do some investigating today. The gauge not working was because the lead under the tank was not connected. After re-connecting that, the temp gauge worked fine. I ran it long enough to peg the gauge, but the fan did not kick on. I need to recheck the fuses since I believe one is for the fan.

I read somewhere where a check to see if the antifreeze is circulating is to see if the radiator gets hot. It did. So, while it did not rule out the thermostat, it does look like the pump is working. I hope anyway.

So some progress. The more I run it, the more I see that I really need to redo the carbs before I get it on the road. I don't think the PO did a very good job with them.

 

run a tank of high test with a good dose of seafoam through those carbs before pulling them out, they are NOT fun.

 

JoeFriday,

I also need to redo the carbs on my Maxim-X. It is running fine but when I last wanted to fine-tune it, I discovered 1 idle/mixture screw would turn, 1 had the screw head broken off, and two were frozen. My plan was to order the rebuild kit from chacal (our local forum parts dealer) but then my fork seals started leaking so, being a safety issue, that's my number one priority now.

Keep me apprised of your rebuild. I'm interested in your progress since I also have a Maxim-X.

Artie(RT)

 

mcrwt644,

I'm actually running seafoam through it now. I want to double check the idle jets, so it may not be a complete rebuild. I am waiting on airbox parts, so I am running it without the airbox now. I know some of the problems I am seeing are related to the missing airbox, but I am not sure all of them are.

 

I have encountered more than a handful of "fan not working" issues where the thermoswitch was caked/corroded badly enough to inhibit the sensor from reading the coolant. Pull the sensor, clean it off with a wire wheel and be sure to smear some sealant on the threads upon re-installation.

 

Thanks Robert!

There is not much room to work with in that space, so I am guessing the only way to pull that sensor is to remove the top thermostat housing, correct?

 

Sorry amigo, I don't know the first thing about your X. I have only seen one in person and the fellow wouldn't let me mess with it (not that I blame him).

 

Well Robert, it looks like your theory will be spot on. I created a test lead and was able to wire the fan direct and it worked. I replaced the fuse just in case and ran the temp up again. No fan, so the only thing left is that thermo switch.

Once I figure out how to get that switch out and checked, I'll let you know for sure. This one will be a trick for sure.

 

I had the same sort of issue with my x. The PO had the fan directly wired to the batter and had a toggle in between. It was nice to be able to switch it off and on at leisure, but I'm a bit of a stickler when it comes to my own bike and originality (factory that is). I replaced the entire fan assembly. I presume that the switch itself was bad as the connections were ok.

Be careful with those mixture screws, those little suckers' heads strip very easily. I've got an extra set of carbs for just such an occasion.

 

It is rather a simple mod to leave the thermoswitch in-line with a manual switch. I've done this mod a few times on various cars/bikes. And it can be done without hacking the harness. Simply determine if a ground is supplied to the fan relay through the thermoswitch or if it switches voltage and provide a switched source of power or ground (based on what you find out).

 

I'm planning on cracking open the thermostat housing this weekend. I was in O'Reilly today getting a couple of things and noticed that they carried MotoRad thermostats which is what maxim-x.com has identified as a replacement. So, I asked if they happened to have the 2040-180. They did a cross reference check, and it looks like the their number is 15868.

I looked at the pics of the MotoRad on maxim-x.com and it looks to be the right one. So, I shelled out the $7.99 and picked one up. Beats the ~$40 that Yamaha wants.

After I get through with the tear down/replacement, I will report back on the results. If this works, this will be a great find.

 

Just in case anyone else runs across this later, the problem was a bad thermal unit. I followed the service manual troubleshooting, but in case someone does not have the service manual, here is what you do.

Take the blue and brown wire off of the thermal unit. Jump the two terminals with the key on. If the fan kicks on, then you are probably looking at the thermal unit as the failure point. If the fan does not kick on, then the fan motor is probably bad.

One last step to verify the thermal unit, take the brown wire, turn the key on, and connect a voltmeter. If you are getting voltage to the brown wire, then you have narrowed it down to the thermal unit.

You can purchase a new thermal unit or take a gamble with fleabay which is what I did. I picked up a complete thermal housing including the thermostat. I now have a spare thermostat and sensor for the temp gauge.

On the subject of thermostats, you can pick up the MotoRad unit that the maxim-x.com site recommends at Oreilly. The name on the box is Murray Ultra, but it is a MotoRad thermostat. The part number is 15868 and should cross reference to the maxim-x.com MotoRad part number.

 

Cool glad you got it sorted out.

 

Good deal on getting the fan going and thanx for posting the info for others. Now before you even think of touching the mixture screws forst look to see if you have the caps. If you don't well thats good and bad. It means they have been moved but also that moisture has gotten to them. Start now and everytime you think of it for a few weeks prior to messing with them put either some 3 in one oil or a very small amount od pb blaster. wd something right on top of them to let it seep down and help them move better.

 

I've been chasing a similar problem, but mine started as a leak around the thermo housing upon removal i found that the previous owner had had it apart before and used rtv sealant which was now leaking. After I opened the housing i found the rubber thermostat ring but no thermostat at all. So does anyone here know the part # for the thermostat itself or a replacement ? i do know the stat is 52mm outside diameter and 180 degrees open but can't seem to find one.

 

no thermostat at all 8O

Late reply, but just in case:
all of the X's use OEM part number = 3GM-12410-00-00