300exc overheating

[flyingcr250]

i was at the sandpit the other day mucking round on the trails course, within half an hour my bike was was boiling over out the overflow same thing happened at the beginning of the 2man, is this normal for the 300's?? a couple of people have told me to swap the radiator cap for one off the '09?? what about an overflow tank?? anyone else have this problem?

[kezzafish]

dunno about your bike particularly but katos seem to me to boil over more easily than other bikes i've noticed. My mates 400 exc did it real bad (his pace is very 'relaxed' lol) he put a KTM fan on it with a thermal switch and it sorted it... the fan has mega grunt. Cost him about $300 for the whole kit

[kezzafish]

another point might be to try bleeding the system... another mate with a 450exc had an air lock and he found a little bleed plug near the head of the motor which solved his overheating problem

[barty5]

ive notice on a lot a ride ktm boil real quick check the cap and seal for damage and make sure there in no crap under the seal rubber etc etc.
Check the radiator are clean and not clogged with mud and crap fine layers can build up. after that i would be doing TK tests etc.

[flyingcr250]

its ok when im moving, but when i get stuck or just putt around for a bit is when it starts to boil over.

[barty5]

could be wrong but i thought i heard some say once the a lota KTMs had thermostats if so id check its workin

[cheese]

Can you just get a catch tank for it?

[barty5]

Can you just get a catch tank for it?

wont help if it boiling its doing it for a reason better to find out why or it will get real costly

[flyingcr250]

Can you just get a catch tank for it?

i was thinking that, noobi has a trick one on his spanish shopping trolley(gas gas) that wraps round the front of the steering head between the forks. i dont think mine has a thermostat. maybe ill try bleeding the system and put some new coolant in.

[dafydd roberts]

i was at the sandpit the other day mucking round on the trails course, within half an hour my bike was was boiling over out the overflow same thing happened at the beginning of the 2man, is this normal for the 300's?? a couple of people have told me to swap the radiator cap for one off the '09?? what about an overflow tank?? anyone else have this problem?

I see one KB members KTM boil on a regular basis and I mean boil - but the thing just keeps going and going, although there is a huge amount of steam there still seems to be plenty of water left in it.

I also see a WR that lives on the rev limiter that seems to keep going and going as well :rolleyes: I think this weekend it will finally explode though :Pokey:.

[dammad1]

Make sure it's not running lean now you guys are in a cold winter.

Mine only ever did it a couple of times once when I was sitting running for a long time on a hot day waiting to start a race, and twice when I was climbing a really long and muddy hill where it was reving hard and spinning all the way.

You can change to a different pressure cap which is suppose to help and also alot of guys fit a small fan which is really easy to do, I thought about doing it but it never really was a major issue.

I would defiantely check your jetting though as I would always make a slight change between summer and winter.

[flyingcr250]

Make sure it's not running lean now you guys are in a cold winter.

Mine only ever did it a couple of times once when I was sitting running for a long time on a hot day waiting to start a race, and twice when I was climbing a really long and muddy hill where it was reving hard and spinning all the way.

You can change to a different pressure cap which is suppose to help and also alot of guys fit a small fan which is really easy to do, I thought about doing it but it never really was a major issue.

I would defiantely check your jetting though as I would always make a slight change between summer and winter.

ill check my manual there's a chart in the back with ambient air temps and different jet sizes etc...

[dammad1]

ill check my manual there's a chart in the back with ambient air temps and different jet sizes etc...

Yeah manual wasn't quite right though, I think it was a bit rich, but better to be a bit rich than a bit lean.

[Ktmboy]

Ya, dis is normal...

Mine did it all the time. I've taken the thermostat completely out as ChrisKTM has also done and it makes a huge difference especially when I'm marking out tracks and doing all the slow riding. We don't really need a thermstat here unless you live in the Waikato with the cold frosts:Pokey:. Just make sure you warm your bike up properly.The 2010 model come out with a 1.8 bar radiator cap while mine has a 1.4 bar cap.

[flyingcr250]

Ya, dis is normal...

Mine did it all the time. I've taken the thermostat completely out as ChrisKTM has also done and it makes a huge difference especially when I'm marking out tracks and doing all the slow riding. We don't really need a thermstat here unless you live in the Waikato with the cold frosts:Pokey:. Just make sure you warm your bike up properly.The 2010 model come out with a 1.8 bar radiator cap while mine has a 1.4 bar cap.

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

[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...:Pokey:
here's a quick make for an expansion/overflow tank.
http://www.thumpertalk.com/forum/showpost.php?p=6449911&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...:Pokey:
here's a quick make for an expansion/overflow tank.
http://www.thumpertalk.com/forum/showpost.php?p=6449911&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?

[Ktmboy]

Its got nothing to do with all of the above. The 300exc, up to 2009 are prone to getting hot. Why do you think they made adjustments to the radiator cap for the last version.

Yes, I take Dangers view that the enduro scenario is relevant. But when you are man handling the freakin thing for 30 minutes(not just a simple hill climb)in first gear through jungle then it makes no difference if its summer or winter. If you are doing the wires then I'd be doing surgery.
Removing the thermostat increases the volume of coolant through the radiator as there is a restriction where the thermostat housing is.
Simple trail riding or enduro racing then a bit of coolant spew is ok.

[4stroke]

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?

water wetter has corosion inhibitor in it and also an anti-freeze agent, down to about 5 degrees below tho. but as for anti-boil this stuff is incredible, pure water has a better cooling efficiantcy then anti-freeze\water mix

[flyingcr250]

water wetter has corosion inhibitor in it and also an anti-freeze agent, down to about 5 degrees below tho. but as for anti-boil this stuff is incredible, pure water has a better cooling efficiantcy then anti-freeze\water mix

were do you get water wetter from??

[camchain]

Its got nothing to do with all of the above. The 300exc, up to 2009 are prone to getting hot.
Woops. Mainly first line of my post was really meant for flyingCR. Rest of it way too general for this thread I s'pose. Point taken, didn't mean to confuse the issue.

[4stroke]

were do you get water wetter from??

BNT i where i got mine from, make sure you get the pinky coloured stuff not the purple stuff--thats for diesels and trucks etc.

here i found this, should answer some q's
http://www.expotv.com/videos/reviews/5/67/redlinewaterwetter/173095

[B0000M]

BNT i where i got mine from, make sure you get the pinky coloured stuff not the purple stuff--thats for diesels and trucks etc.

here i found this, should answer some q's
http://www.expotv.com/videos/reviews/5/67/redlinewaterwetter/173095

i run the diesel stuff in mine.

apparently the diesel stuff is better suited as diesels tend to run hotter- much like our bikes

added bonus too is the bottle is bigger

[4stroke]

good point, hadent actually thought bout it like that.

[IIIRII]

Do a search on tardme , I spotted 1 litre of coolant with very high boiling point for about $40 specifically for bikes....
Under bikes / parts , I think ....
Dont have tardme at work sorry or i'd post the link.

[barty5]

Do a search on tardme , I spotted 1 litre of coolant with very high boiling point for about $40 specifically for bikes....
Under bikes / parts , I think ....
Dont have tardme at work sorry or i'd post the link.

http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Parts-for-sale/Performance/auction-232780828.htm


added it for yah

[dafydd roberts]

I run a temp gauge on my bike I got a little stuck the other day, was registering 135C for about 30min on the clock still wasn’t boiling. I just run a standard antifreeze/summer coolant 50/50 from super cheap.