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Overheating 450RR

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Hey Guys,

I have a 2010 450 RR that is overheating. I've changed the coolant over to Evans (it did it before that too). The bike has the auxiliary fan (he added) and the previous owner told me that it has a high flow up water pump. I believe him as this was originally a dealer bike and it has lots of extra bling.

The fan kicks in and works, I've heard it. I've bled any potential air out of the system a few times. The bike has plenty of coolant. 

I do have the larger desert tank on it, which wraps around the rads so there is less air flow vs the stock tank. It only has stock rad guards installed at the moment.

I may have to give up and take it to the dealer but was hoping you all could give me a few more things to check before I do that.

Thanks in advance,

Chris.

 

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Did you just get the bike? Was it overheating before? How do you know it's overheating? Is it pissing out of the overflow?

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The bike is a recent purchase. Since changing to Evans it is not pissing out, as there's no pressure in the system. 

However before Evans, yes. The prev owner indicated that it overheated and I also experienced this, pre and post Evans. 

Chris.

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What is the symptom of the overheating? Does it happen when your going slow? At idle? Regardless? I ask because depending on what it's doing, it can be narrowed down.

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When the engine gets above 260F (ish) it loses all power. It does it at low speed/single track and I can re-create the problem in the garage, sitting still.

Chris

 

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Where are you getting your temp from? Is it the coolant temp or the engine temp? Are you smelling coolant when it overheats? Your comment about not having pressure in the system has me wondering. If your your cooling system is experiencing overheating, you should have some pressure build up. Usually you would have some coolant coming out of the overflow. You would probably smell coolant prior to your overheat symptoms. Are you experiencing and back firing, decel pop, or bogging prior to the overheating?

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Evans coolant is waterless, and boils around 350, so that means there is no pressure in the system, so there will never, ever be anything coming out the over flow.

The temp readings I am getting are from the trail tech.

When it overheats there is no power, it bogs.

This bike is jetted with the JD Jet kit, and it does pop on decel.

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Have you checked for possible air leakage into the intake? Exhaust nice and tight with no header leaks? If the coolant is flowing and your cooling fan is coming on, it could be something's creating a lean condition which would make the engine run hot. It may be worth asking the prior owner if he put the hi flow water pump in for a reason, and when, in relation to the overheating problem. Does the bike have a thermostat? If so, replace the thermostat and pressure cap if you have not yet just to rule out the simple. Check your carb boots for leakage. You can spray a little starter fluid around the boots while it's running and listen for a change if your not sure.
Your bike has the fcr 39 carb. Make sure the fuel screw has the rubber o ring and washer and is properly adjusted. Hold a lit cigarette or equivalent at the header flange while running and see if there is an air leak. Shut the lights out and start the bike, if your header start to glow within a minute or so, you may have an air problem. If you crack the throttle and have any flame coming out of the exhaust, same thing. RFS motors can be finicky beasts when it comes to air. Make sure your filter is oiled and your throttle valve is installed and operating properly as well because if not the tendency is to play with idle and fuel screw to compensate often resulting in lean conditions.

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3 hours ago, _chris_ said:

Hey Guys,

I have a 2010 450 RR that is overheating. I've changed the coolant over to Evans (it did it before that too). The bike has the auxiliary fan (he added) and the previous owner told me that it has a high flow up water pump. I believe him as this was originally a dealer bike and it has lots of extra bling.

The fan kicks in and works, I've heard it. I've bled any potential air out of the system a few times. The bike has plenty of coolant. 

I do have the larger desert tank on it, which wraps around the rads so there is less air flow vs the stock tank. It only has stock rad guards installed at the moment.

I may have to give up and take it to the dealer but was hoping you all could give me a few more things to check before I do that.

Thanks in advance,

Chris.

 

You could yank the thermostat too. That could be a problem. It helped with my 525 in cooling . i'd say get big radiators..but idk if the big tank you have makes that a problem... You doing slow single track and clutching alot? I don't like evans because it masks cooling to me.. and what is the jetting? That  JD kit could be a problem too.. go back to stock if you can.. just to get a control setting.

Edited by hawaiidirtrider

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2 hours ago, _chris_ said:

Evans coolant is waterless, and boils around 350, so that means there is no pressure in the system, so there will never, ever be anything coming out the over flow.

The temp readings I am getting are from the trail tech.

When it overheats there is no power, it bogs.

This bike is jetted with the JD Jet kit, and it does pop on decel.

Bogs as in fuel starvation, or no spark, or no air.......specifically, what is the symptom.

A rich bog is a gurgle, a lean bog is like a kill button. A loss of spark bog is like shoving a rag in the intake.

 

....because there is no reason for the carb to stop working and the combustion to cease because of more heat. It would just sieze if the engine was over heated to much, or you would fry the oil and it would stop lubricating...again, seizing something like the cam journals.

Trail tech temp sensors are +/- 15%, so don't rely on that information. 260 could actually be 221....only a laser heat gun pointed at the left radiator hose can tell you the actual temp.

So, the only symptom is the loss of power at max temp......that to me sounds like vapor lock (tank not venting, fuel line boiling fuel) or loss of full spark (failing stator output to coil, preventing full capacitor charging), or an ECU that is overheating (spray it with a can of compressed air to lower it's temp).

You should have ZERO deceleration popping. Adjust the fuel screw out 1/4 to 1/2 turn. If that does not do it, you have a compromised pilot circuit; a partially clogged pilot, pilot pasage above the jet, or a bad/leaking hot start (a very minor leaking plunger or broken spring cap causing the loss of plunger pressure).

If you did have a lean condition in the pilot, and you are trying to over compensate for it by turning out the fuel screw past 1.5 turns, this WILL cause the bike to run very hot, and it will provoke symptoms of 'bad cooling', which would not be the problem. The problem would be excessive leaness at first 1/4 throttle only, and make it run extremely hot.

 

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Good points. Thank you.

Hmmm... Its been a while since I rode it and it happened. (Hot here in AZ). It bogged when I snapped the throttle and just had no power. It was like running out of gas so likely lean.

I will adjust the fuel screw & find some time to take it for a rip and check the plug.

 

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1 minute ago, _chris_ said:

Good points. Thank you.

Hmmm... Its been a while since I rode it and it happened. (Hot here in AZ). It bogged when I snapped the throttle and just had no power. It was like running out of gas so likely lean.

I will adjust the fuel screw & find some time to take it for a rip and check the plug.

 

See, now you are getting more specific.

Quick throttle bog is 100% the accelerator pump and has nothing to do with jetting.  Jetting is slow throttle response only. Fast is the apump.

Service your apump system.  If you have not been treating your gas since day one, the pump system is probably corroded. 

There are many points of failure in the apump system, but the most common are the diaphragm being worn out, or corrosion inside the passage ways.

An apump system maintanence tutorial is available upon request.

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6 minutes ago, _chris_ said:

Interesting. Why would it do it only when hot? As soon as the bike is cooled 10-20F it was fine.

 

It wouldn't .  That symptom is something else. 

You need to find out if the issue is time or heat.  

It sounds to me like you have fuel starvation issue (bad tank vent) or a failing stator.

 

 

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Yes-Especially if there is a clogged pilot circuit will further aggravate the situation. Some may start to play with idle speed and fuel screw in this circumstance. It's important to remember that idle screw adjustments also affect the a pump timing which can advance or retard the a pump squirt. Check/replace pilot, adjust fuel screw and idle, then check a pump timing. Of course this will be in vain if there is any other air infiltration issues.

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The one thing not mentioned is overheated fuel - could be a partial vapor lock and an easy check would be to loosen the gas cap to see if that helps. Is the 2010 the KTM engine? If so I know even in our part of the world they were overheaters, perhaps putting on a reflective product on the underside of the tank would help mitigate that.

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This is an old thread from 2011... in this one the cap has like a valve in the cap or something?  is there a ball or something? I didn't have this year gas cap so don't know but once that was cleared to make it a simple vent the  gas boiling and problem went away on this bike...  Whatever you do don't put on the brass swivel one way valve  from moose racing that goes in the gas cap vent.. I put it on my 525 and had gas boiling problems.. I just put it back stock and it was fine.. don't buy this.. 

Untitled-45.jpg

I had to search a little but in this case with this 400 Beta years ago       it was the valve in the gas cap.. cleared that and no problems if I remember right..

With my 525 I had that moose swivel one way valve that i thought would be good.. it boiled fuel in my big ims tank for my 525 and it actually made the tank swell and expand..:eek:  don't use that swivel.. and if this is the problem with your bike.. the valve in the cap ..well then how nice and easy.. if not then go back and check the other stuff.

Edited by hawaiidirtrider
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