300exc overheating

[Ktmboy]

so would taking the thermostat out for summer make it run a bit cooler and maybe put it back in for winter?

I've thrown mine away, nada, no more, not again. Not summer or winter.

[noobi]

the tank on my bike is an expansion tank not an overflow tank. its pressurised. your just jealous cuz your kato doesn't have one...
here's a quick make for an expansion/overflow tank.
http://www.thumpertalk.com/forum/sho...1&postcount=21

i think the logic behind it is, when the bike boils over, you lose some coolant, so if you keep over heating the bike your gonna lose a fair bit of coolant, making the bike more susceptible to over heating. unless you replace the coolant with river water or something.... so if you put an expansion tank on it, like on my bike, you wait till the bike is cool again, open the cap and all the coolant goes back into the radiators. no more lost coolant.
that's what i think there for anyway

[flyingcr250]

the tank on my bike is an expansion tank not an overflow tank. its pressurised. your just jealous cuz your kato doesn't have one...
here's a quick make for an expansion/overflow tank.
http://www.thumpertalk.com/forum/sho...1&postcount=21

i think the logic behind it is, when the bike boils over, you lose some coolant, so if you keep over heating the bike your gonna lose a fair bit of coolant, making the bike more susceptible to over heating. unless you replace the coolant with river water or something.... so if you put an expansion tank on it, like on my bike, you wait till the bike is cool again, open the cap and all the coolant goes back into the radiators. no more lost coolant.
that's what i think there for anyway

or i could hook a hose up from the radiator to my camelbak ha ha ha. think ill try the thermostat idea. is it an inline one or is it mounted on the motor somewere?

[barty5]

same principal as cars you shouldnt really change the cap to a higher pressure cause this allows the motor to run hotter then it was designed to as it has to get hotter to boil

[xen]

Cool link noobi, that looks easy to make, might try it sometime. When mine boils it really goes but don't seem to lose too much coolant.

[xen]

same principal as cars you shouldnt really change the cap to a higher pressure cause this allows the motor to run hotter then it was designed to as it has to get hotter to boil

Thinking that its fine as the '10's haven't had engine upgrades but they have put the 1.8 cap on so they must be wanting to fix the problem, hear its common for the 300s. Think the radiators are the same size between the 125,250 & 300 models so makes sense they'd boil quicker

[B0000M]

I've thrown mine away, nada, no more, not again. Not summer or winter.

good idea. none of the other bikes have them - why would ktm need it

[Danger]

good idea. none of the other bikes have them - why would ktm need it

The KTM has a thermostat for the cold starts required during enduros, it is an enduro bike and a MX bike does not need this requirement. If you are not competing in enduros you could remove the guts of it but I like to keep mine in during winter and remove it for the summer, not that I really have overheating issues on the 200. Its always a good idea to warm the bike before riding if you can, most wear on an engine is on a cold engine, but you can't do this in enduros.
The key is to keep moving and to keep the air flow going, not always possible in some situations. Often tho it will be just the result of the water expanding that comes out the overflow and if you keep topping it up it will expel during the next ride. Just make sure the water level is covering the entrance to the cores.
Removing the guts from the thermostat may not necessarily help in low speed situations but it will run cooler for longer and perhaps delay an over heating situation so its still a good idea to remove the guts of the thermostat to help with the flow if cold weather or cold starts are not a factor.
Some late model KTM's (08 onwards I think) have rerouted the water passages through the frame, these bikes over heat even more and it helps to reroute the water passages with external hoses like the earlier models.
And yeah, check your jetting, a lean engine runs hotter. And a cheap fan can be added if your doing lots of slow stuff where overheating is a problem, I think a PC fan can work but have never done the mod myself.

[IIIRII]

A few points to clarify
Thermostats do not make your cooling system work better, all they do is stop water circulating when cold , to assist in getting the water in the engine up to temp, then they open and ALL the water in the system circulates around through all the cooling system.
Higher pressure caps "can" cause other issues like porosity ie or finding or causing a leak somewhere else because the rest of the system isnt designed to run slightly higher pressure.
Are you running 100% ethylene glycol ? (antifreeze)
Also , water wetters do work , so sometimes an additional chemical in the system will assist in a more stable temp.
Radiator fans work, but obvuiosly add weight and more shit to fail.
I would through the thermostat in the rubbish, I have never run one on any water or oil cooler on any race engine I have owned and never had any issues.
Warm it up slowley, then thrash it.

[Danger]

A few points to clarify
Are you running 100% ethylene glycol ? (antifreeze)

To clarify this point, anti freeze does not remove heat from engine parts faster than water. Ethylene glycol has a lower specific heat than water so the mixture is less efficient at removing heat than plain water. In an engine running just antifreeze the engine tends to run hotter. More of the mixture needs to be moved faster to achieve the same cooling. It does however raise the boiling point of the mixture. A 50% mix is more common, I've heard of others running a 70% mixture of water and 30% antifreeze for greater cooling efficiency. The benefits of running anti freeze besides the obvious anti freeze advantage is the anti corrosion agent of Ethylene glycol.

[Danger]

Warm it up slowley, then thrash it.

Could be hard to do in an enduro which these bikes are designed for. Other wise yes. But I've noticed that my bike in really cold conditions without a thermostat fitted actually runs very cool, the radiators are only warm and I don't think this is necessarily optimum. Depends on where you ride the bike, how much air flow you get on the rides etc. In cold weather my bike really cools down with a short break, and again most wear is on a cold engine.

[flyingcr250]

cheers for the advice everyone, i think ill live with it at the moment, its only done it twice and only when im putting around.

[Reckless]

Just a couple of wee small points for you to note.
The Ktm water level in the radiator is not up to the neck of the cap on my 08 200 its only 10mm above the finns when cold so most of the tank is empty as standard. So make sure your not just lossing the too much extra your topping it up everytime, if you are?
My 200 overheats on the odd occasion like on the big dipper at the sandpit, it seems to spew out heaps of water but I only think its really a little bit. It just looks like heaps because there a shit load of steam off the pipe. There is Actually bugger all change when I check it back at the trailer.
Do check your plug reading and the jetting because changing mine back to standard compression has helped this alot (haven't had it since) so it could be running a little hot if its lean?
The engine should be able to take the 09 raditaor pressure of 1.8 bar? I think the engines are pretty much the same. The 09 brochure states that it was for temperature stabalisation, so check it out, this could be good to try?
Then of coarse you have the thermostat mod as Ktm boy has done.
Anyway just a bit of helpful info I hope. Cheers!

[4stroke]

the only fluid i run in the radiator is strait distilled water and a product called "water wetter" its made by a company redline, ran it in the race cars and in my road car, nothing could touch it, had it in the stockcar and we went from comming in after a race boiling over to at a normal hot temp, wicked stuff, i run it in the husky at the mo.

[camchain]

is it an inline one or is it mounted on the motor somewere?

Thermostat sits inline where your hoses join under the fuel tank.

I've heard the big-banger katoom is a bit more prone to boil ups. I've had my 200 pretty hot when running hard in deep sand though, & have thought about removing the thermostat for summer. Advantage as I understand is improved flow rate at this point. Never eyeballed it but certainly must be something to it if Birchy does it. I prefer the idea of my bike getting up to operating temp faster but might try removing it for summer.

Would pay to check your hoses for kinks that might interfere with flow as well. The hose coming off the head on mine used to be a bit too long and this caused a pronounced flat spot in it at the tightest bend.

When I first got mine, it lost a little coolant every ride so I ordered a new rad cap. On close look I noticed cap wasn't sitting square & flat. Rad filler neck had taken a knock at some point and lip was a bit distorted. Ali on these rads is very soft (was easy to straighten out) & no lost coolant since.

Barty made a good point about keeping the fins/cores as clean as possible. You can't hit 'em with pressure washer so they may not be as clean as they appear at a glance. When I did my top end I soaked my rads (twice) overnight in buckets of hot water laundry detergent & nappisan. Gave 'em a good swish back & forth in water. A surprising amount of extra crap came off them. Even a thin layer of this probably not good for heat dissapation. I even went to trouble of straightening out the bent fins to make 'em pretty again, also easier to wash & less likely to hold dirt.

Re what Danger noted about water being the superior part of your coolant recipe. I've heard of that before. Apparently water 'sits better' (for want of a better term) against hot metal & enables better heat transfer? I use that 'Engine Ice' brand stuff and was going to try a 25/75 ratio last summer but it says on pack to leave it 50/50, so I didn't try it. Can't really see the harm though. We don't really need the antifreeze factor much here & you'd think 25% ratio of whatever anti-corrosion agent is in there should be enough if using distilled water? Be interested to know more about this. You don't worry about corrosion 4 stroke?