300exc overheating

**flyingcr250** · 30th July 2009, 21:16

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** · 30th July 2009, 21:23

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** · 30th July 2009, 21:26

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** · 30th July 2009, 21:27

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** · 30th July 2009, 21:32

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** · 30th July 2009, 21:38

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

**cheese** · 30th July 2009, 21:51

Can you just get a catch tank for it?

**barty5** · 30th July 2009, 21:56

Originally Posted by cheese

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** · 30th July 2009, 21:59

Originally Posted by cheese

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** · 30th July 2009, 21:59

Originally Posted by 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?

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

I think this weekend it will finally explode though

.

**dammad1** · 30th July 2009, 22:04

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** · 30th July 2009, 22:13

Originally Posted by 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.

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

**dammad1** · 30th July 2009, 22:21

Originally Posted by flyingcr250

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** · 30th July 2009, 22:22

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

. 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** · 30th July 2009, 22:30

Originally Posted by 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

. 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?