Kawasaki KLR Forum banner

1 - 20 of 29 Posts

·
Registered
Joined
·
341 Posts
Discussion Starter #1 (Edited)
I just finished a 685 kit install, and now my bike overheats. It seems fan switch may be bad, since fan does not want to come on. I put a little jumper on the switch, and the fan runs fine. Gonna test the switch in a pot of hot water as soon as engine cools a bit.

But here's my real question: should the fan be needed 100% of time in order to avoid overheating? I rode 5 miles today with all plastics off, and temp gauge headed toward the red if the fan was not on. No idling, no traffic, speeds of 30-40 mph, and air temperature of 65 degrees. But when I added the jumper, and forced the fan to come on, the temp needle stayed horizontal for the next 5 miles. This is in the "normal" range, but certainly hotter than I would have expected on such a cool day, with all plastics off.

I've got good flow in my radiator, and I've burped the system of air pockets. Kit was from Eagle Mike. I also just now replaced my thermostat thinking that was contributing to the problem, but now it looks like the fan switch. (Hope not: a new one is >$100.00!!
 

·
Registered
Joined
·
171 Posts
my cooling needle is always VERY LOW, and a tad higher than COLD on highways
im in southern california, so weather is pretty warm.

the needle hits little over the middle when doing lots of offroading, slow speeding, running on first gear most of the time for hours.
 

·
Registered
Joined
·
171 Posts
i did however hear that previous model of klrs had overheating issues and the new ones have bigger cooling systems, mine is 2013.
im not sure if that is correct.
 

·
Registered
Joined
·
5,547 Posts
I just finished a 685 kit install, and now my bike overheats.
Define, "overheats." If your coolant doesn't boil, and the temperature gauge stays out of the far right red zone, that's not overheating, IMHO. Yet, the cooling system should stabilize coolant temperature somewhat less than such an extreme.

Fan should NOT run continually; only activated when coolant in bottom of radiator exceeds 201 degrees F., activating thermal switch. I'd expect a continually operating fan to have a limited service life.

From your post above, understand your thermal switch never closes, regardless of temperature.

Does coolant temperature gauge ever stabilize at a point lower than the far right red zone, without manual activation of fan (e.g., when riding in cool ambient temperature)? If not, a coolant circulation problem may exist.

Otherwise, I've experienced no cooling problems with my Generation 1, with operational thermal fan switch.
 

·
Registered
Joined
·
341 Posts
Discussion Starter #5
Mine is a 2009, so the red area is at top of gauge, not on the right. Anyhow, with fan running, needle settles at horizontal, or half way to the red. With no fan, needle goes to red. But by then, bike has already stalled. I try to avoid that.
 

·
Administrator
Joined
·
8,256 Posts
Do you have a Thermo-Bob installed?

Make sure that you didn't incorrectly connect the inlet and outlet hoses to the water pump. It's easy to do.

Make sure that the hose that is on the nipple that is labeled "Cyl" goes to the front of the cylinder, not to the radiator.

If they are crossed up then the coolant will not circulate with a T-Bob installed. Not sure how it would affect a system with no T-Bob.

If you don't have a T-Bob, then I'd suspect some blockage somewhere, either from an air pocket or debris. Might consider removing the elbow from the front of the cylinder and see what comes out.

If the bike is in motion then fan will seldom, if ever, come on unless the ambients are in the 100 degree range.

Let us know.

Tom
 

·
Registered
Joined
·
6,645 Posts
clogan,
Did you have the water pump cover / clutch cover off during this rebuild?

If so, I'm guessing that you left the water pump nut loose! Your circulation is not as swift as needed.
 

·
Registered
Joined
·
341 Posts
Discussion Starter #8
Did not have water pump cover off. By overheating, I mean needle pegs to red area, engine locks up/stalls/dies (three instances), and coolant spews out overflow under rear fender (first instance only). Hoses to radiator were cris crossed for first instance, but then corrected. Last two overheating instances had hoses oriented correctly.
 

·
Administrator
Joined
·
8,256 Posts
Wellll, it's physics. If the coolant circulates then the engine doesn't overheat.

I'd heed Paul's suggestion and remove the pump cover just to make sure it's all good. Bump the engine and see it turn.

After that, I think you're looking for blockage of some sort, so you might want to pull the hoses and make sure they are clear. Remove the cylinder nipple and make sure there's nothing blocked in it or in the base of the cylinder. Pour water in the top of the radiator and watch it fall out the bottom. Remove the T-Stat and pour water in and watch it run out the bottom of the cylinder.

It's tedious, but you'll find it. The key is to see things work as they should, one piece at a time.

Tom
 
  • Like
Reactions: gruet782

·
Registered
Joined
·
341 Posts
Discussion Starter #10
Thanks, Tom, Paul, everyone. Gotta take it a step at a time. Good outline, Tom. That's what Ill do when I next can get to it. Soon as I find the point at which water doesn't flow, Ill know where the blockage is.
 

·
Registered
Joined
·
82 Posts
2009 over heating

Not sure if this is the cause, but on my 2009 the plastics force the air flow through the radiator. If the cooling works when the fan is on does that mean that the rad. is not getting air flow without the plastics? How is the cooling with the plastics installed? Ride safe James
 

·
Registered
Joined
·
191 Posts
Did not have water pump cover off. By overheating, I mean needle pegs to red area, engine locks up/stalls/dies (three instances), and coolant spews out overflow under rear fender (first instance only). Hoses to radiator were cris crossed for first instance, but then corrected. Last two overheating instances had hoses oriented correctly.
Don't want to spread alarm here but when a very hot engine 'locks up and stalls/dies', that speaks to me of bad things happening in the cylinder...

iddy
 

·
Registered
Joined
·
5,547 Posts
Don't want to spread alarm here but when a very hot engine 'locks up and stalls/dies', that speaks to me of bad things happening in the cylinder...

iddy
Same thought crossed my mind, iddy!

Only personal experience was with a 2-stroke (Tohatsu); tear-down, cylinder/piston/ring inspection, cylinder honing and reassembly: fortunately, good-to-go in that case (and, belive me: It would GO!).
 

·
Registered
Joined
·
82 Posts
Still curious?

Not with standing that there may well be other factors involved, I am still curious.
How important for adequate air flow is the shape of the plastic fairing.The plastic seems to funnel the air into an area of one half to feed the radiator. Seems that without this funneling the air flow might be insufficient for proper cooling.
I have never run my 2009 sans fairing so I just don't know.
Appreciate any comments. James
 

·
Registered
Joined
·
241 Posts
I been reading this thread with much interest because I have considered pulling all my plastic and running 2 headlights.

I do know on many, many cars all the plastic on the front and under the car is REQUIRED for proper airflow to the radiator. Many older vehicles would over heat without a fan shroud.
KLR may require it...

There's my 2 cents, I'll keep reading.
 

·
Registered
Joined
·
5,547 Posts
Doubt the KLR650 plastic is of any significant consequence regarding cooling; however, if so, an operational thermal switch will activate the cooling fan whenever necessary, IMHO.
 

·
Registered
Joined
·
1,260 Posts
No, the fan doesn't have to run all the time. The slower you go and the hotter the air temperature the more it runs. Stop and go traffic on a warm day will have it running constantly.

You have already proved the fan is good by jumping the harness plug at the fan and you say the temperature stays at mid-range with the fan jumped on. So, you know the fan switch at the bottom of the radiator is bad. If you are looking of some solution that will keep you from having to replace the switch ($100), you are out of luck. Why don't you replace the bad switch?

If you want to play with water flow, here is some information for you to work with. When you are done you will need to refill with a proper antifreeze mixture.

RADIATOR FLOW RATE: 2009 is the same as 2008

My '08 pumps 21.1 liters in 3 minutes and 7 seconds at 1500 rpm. = 5 gallons in 2 min and 48 seconds
and 21.1 liters in 57 seconds at 3600 rpm. = 5 gallons in 51 seconds

I made this measurement by disconnecting the return hose at the top of the radiator. I spliced an extension on to it to make it easier to run the return water into a bucket. I disconnected the little tube to the overflow tank so as not to fill the tank with hose water. I removed the thermostat so that water could flow freely at a steady rate (don't worry about a little leak at the thermostat). I ran water from a garden hose into the fill neck at a higher rate than the pump could empty the radiator so that the extra water always overflowed through the top nipple that I removed the hose from. Also, I kept a gap between the hose and the neck so as not to force water in to the radiator.

After everything was running at a steady state, I but the return hose into a 5 gallon (18.925 liter) plastic paint pail. The pail will hold 21.1 liters when full to the rim and it took 3 minutes and 7 seconds to fill the bucket to the rim at 1500 rpm. I did it 3 times and got very similar results.

I rechecked the flow rate at 3600 rpm with the bike on the side stand and the top radiator hose extended down to the top of a 21.1 liter (brim full) paint pail. The top is 14.5 inches above the ground. It took 57 seconds at 3600 rpm to fill the pail.
 

·
Registered
Joined
·
82 Posts
KLR cooling

Hey rebar,what did you figure out?

Well I am still trying to get this straight. After correcting a problem with hose routing, it now seems as though the OP has a bad fan switch. Okay, I see that. but what confuses me is how a KLR traveling 30 - 40 mph will over heat. Mine stays cool at even lower speeds. It does not appear that the OAT was very high. So, is there another cause or problem with the system.

So, has the OP run the bike with the plastics installed or not? If the air flow from the fan controls the temp then why not the air flow from 30 - 40 mph.

Just trying to learn something here James :mexican wave:
 
1 - 20 of 29 Posts
Top