ktm 450 exc overheating???

[twisted-hog]

i have yet to see a 450 exc that didn't boil like a steam engine

Recently picked up a 2005 450 EXC from a guy in Kelowna.
Have been doing the bolt on goodies and new plastics kit waiting for weather to clear a bit more down here on the coast.

Bike has only has 100 hours and 2500 kms on it. I have taken it around the block a few times and have noticed it puking from the rad overflow tube after only riding maybe 10 mins?

Bike has a fan kit and I just installed a Vapor Stealth Speedo with temp sensor.

Quick rip around the block to check out Vapor install, water temp was only 85 degrees celsius and it started to puke before fan even kicked on?

Water level looks about 1/4 inch above fins.

Now I'm wonder?
Is rad still over full?
Rad cap failing?
Thermostat not opening?
Wrong jetting for coast?
Would bike have been jetted differently for riding in Kelowna? Help here from loops boys, do you rejet for Kamloops altitude?

Thanks t-h

 

[volcon]

Head gasket. Check for oil in the coolant and coolant in the oil. Could be cracked head/liner/cylinder.

 

[twisted-hog]

Just changed oil, oil looked good, coolant looks clean......exhaust gas is clear......

 

[Shuswap]

The clean oil/coolant is a good sign.
So:
Does this model have an overflow bottle, does it keep discharging...or just burp?
They get hot pretty fast with no airflow. Did it puke while riding or idling?
Could have an air bubble stuck in there somewhere. Not sure this engine needs burping or not?
Cap pressure stock? If it's reduced it would shift off its seat sooner, at a lower temp.
Doesn't sound overfilled.
85C is 185F
Need someone with this model to chime in.

 

[twisted-hog]

The clean oil/coolant is a good sign.
So:
Does this model have an overflow bottle, does it keep discharging...or just burp?
They get hot pretty fast with no airflow. Did it puke while riding or idling?
Could have an air bubble stuck in there somewhere. Not sure this engine needs burping or not?
Cap pressure stock? If it's reduced it would shift off its seat sooner, at a lower temp.
Doesn't sound overfilled.
85C is 185F
Need someone with this model to chime in.

No overflow bottle.

To be honest haven't really ridden it besides up and down the street in front of the house a couple times, (hoping to get out this weekend to foot of #8 Rd in Richmond for a short play) then when I pull into the driveway after say 30 seconds of idling there's a burp and a steam cloud.
Fan has not yet kicked on.

Looks like stock original cap, which I'll try and pressure test 1st.

Sometimes it's something so obviously simple that makes you think it can't be a simple a fix like that?

 

[cactusreid]

I replace the stock ktn 1.4 cap with a 1.8. Check your inline fuse if the fan is not kicking in. they draw a lot of current, hence blow fuses regularly. pack a couple of back up fuses. The rfs motor has two burp holes, one on the head, 8 mm bolt just above spark plug on a flat area if i recall, and the right side rad tank has a burp hole on top. Even in kamloops in the summer in slow tight stuff, my ktm fan ( just go buy it cause it works way better than a computor fan) some days never seems to shut off, but the bike does not boil over. also check to see your connections at the temp bung on the rear lower of the rt rad are clean and secure. when your fan is on steady for most of a day, it draws so much that if your also useing your estart alot, you maybe kick starting by 2 pm? Good 7 am battery or higher is a nice add on. I hate kick starting a button bike! It just doesn't seem right.

 

[bkoz]

Did you have the rads right full to the top of the rad cap filler neck?

If so the coolant has to go somewhere as it expands with heat. The rad cap will open and you will steam out the overflow hose until the system pressure comes down and the cap closes again.

When you let the bike cool down you will probably find the water level just above the fins. That's it's happy place, ride it.

But when it comes to summer time single track work and you find the bike steaming like crazy and the water level dropping well past the fins its time to look into jetting/fans/overflow bottles etc.

 

[twisted-hog]

I replace the stock ktn 1.4 cap with a 1.8. Check your inline fuse if the fan is not kicking in. they draw a lot of current, hence blow fuses regularly. pack a couple of back up fuses. The rfs motor has two burp holes, one on the head, 8 mm bolt just above spark plug on a flat area if i recall, and the right side rad tank has a burp hole on top. Even in kamloops in the summer in slow tight stuff, my ktm fan ( just go buy it cause it works way better than a computor fan) some days never seems to shut off, but the bike does not boil over. also check to see your connections at the temp bung on the rear lower of the rt rad are clean and secure. when your fan is on steady for most of a day, it draws so much that if your also useing your estart alot, you maybe kick starting by 2 pm? Good 7 am battery or higher is a nice add on. I hate kick starting a button bike! It just doesn't seem right.

Fan works, it has come on.
Thanks for the other tips. Will test cap and look into upgrading it.
Now I think my water pump may be leaking. Noticed a wet mark coming down from the vent hole by the pump. Now is this another problem or cause of problem?

Did you have the rads right full to the top of the rad cap filler neck?

If so the coolant has to go somewhere as it expands with heat. The rad cap will open and you will steam out the overflow hose until the system pressure comes down and the cap closes again.

When you let the bike cool down you will probably find the water level just above the fins. That's it's happy place, ride it.

But when it comes to summer time single track work and you find the bike steaming like crazy and the water level dropping well past the fins its time to look into jetting/fans/overflow bottles etc.

Level is just above the fins looking down into rad.

 

[bkoz]

I can't remember where the rad overflow hose runs on the old RFS bikes.

On the newer bikes KTM had the asinine idea of running the overflow into the frame at the steering headstock. Any purged coolant would drip right onto the exhaust, steam like crazy and run onto the engine.

 

[twisted-hog]

I can't remember where the rad overflow hose runs on the old RFS bikes.

On the newer bikes KTM had the asinine idea of running the overflow into the frame at the steering headstock. Any purged coolant would drip right onto the exhaust, steam like crazy and run onto the engine.

It's a short 6 inch hose that dumps onto the cylinder side of rad and splashes onto both causing a steam cloud.

 

[bitingdog]

That's so you know it's getting hot. Look into the Boyesen Supercooler water pump upgrade. The OEM pump is a remarkably wimpy looking, whereas the Boyesen is a manly type of water pump. They often have an overstock/blemished sale, so be sure to ask.

Congratulations on getting a dirt bike from this century! LoL

 

[04klr]

the manual says the level should be below the cap. if you extend the overflow hose to a catch bottle installed in the air box with its own overflow dump you will end up with a recoverable overflow just like your car.

 

[cactusreid]

if you change out the water pump impeller, be carefull when you change out the little shaft seals. If I recall there is also a seal on the end of the camshaft, that some times wears a slight groove in the shaft surface. If you put your new seal just a hair outwards or in farther than the last one was, this should stop your leaking.

 

[sylvain]

Put Evans Waterless coolant.
The boiling point is so high, it never boil.
it also do not expand, so no need of Overflow bottle.

And for sure, if you ride hard stuff, adding a fan is a must.

I did the Evans to both of my Beta 400-450, the fan start from time to time but it never boil.
Never boil so No need to add coolant

And it's lifetime coolant, unless you put water in it

Also, never freeze.

 

[twisted-hog]

That's so you know it's getting hot. Look into the Boyesen Supercooler water pump upgrade. The OEM pump is a remarkably wimpy looking, whereas the Boyesen is a manly type of water pump. They often have an overstock/blemished sale, so be sure to ask.

Congratulations on getting a dirt bike from this century! LoL

Checked out their website, looks like they don't make them for the RFS engine.
Thanks, got the bike looking pretty, love the power in even just playing on the street in front of house, now just have to sort out a few small issues before heading to Spring Newbie Ride then onto Odessa.

the manual says the level should be below the cap. if you extend the overflow hose to a catch bottle installed in the air box with its own overflow dump you will end up with a recoverable overflow just like your car.

I've been reading and checking out youtube, everyone says just above fins in rad.
catch bottle will be last resort.

if you change out the water pump impeller, be carefull when you change out the little shaft seals. If I recall there is also a seal on the end of the camshaft, that some times wears a slight groove in the shaft surface. If you put your new seal just a hair outwards or in farther than the last one was, this should stop your leaking.

There's a good video on youtube
RFS Water Pump Seal
with a shop changing just the seals not the impeller that sells a complete kit for $42 US shipping to US address or can I buy all the bits @ Holeshot for about $57, leaning this way. Just checked, a new impeller is cheap, might as well through all new parts in when I open it up.
Thanks for the tips, I've heard mention of the wear on the shaft, Holeshot quoted about $230 for a new one of those, ouch.

Put Evans Waterless coolant.
The boiling point is so high, it never boil.
it also do not expand, so no need of Overflow bottle.

And for sure, if you ride hard stuff, adding a fan is a must.

I did the Evans to both of my Beta 400-450, the fan start from time to time but it never boil.
Never boil so No need to add coolant

And it's lifetime coolant, unless you put water in it

Also, never freeze.

Already have a fan installed, where do you buy this stuff?

 

[Shuswap]

Small amounts of coolant seepage at weep holes is pretty common on M/c engines. The BMW 800 cc series is well known for this.....and no reason to repair. I have zero experience with the RFS motor, but give it some thought before tearing into it. As for the air space above the coolant level, pretty much every engine I have experience with that does not have a coolant recovery tank requires a very significant void below the cap sealing surface, some as much as 2-3". I'd suggest as long as the interior tubes/fins are covered, that would be acceptable. At the least you can start at that level and keep a close eye on it.

 

[sylvain]

I bought it online, but I'm sure you can get it from some DSBC sponsor.

 

[twisted-hog]

Small amounts of coolant seepage at weep holes is pretty common on M/c engines. The BMW 800 cc series is well known for this.....and no reason to repair. I have zero experience with the RFS motor, but give it some thought before tearing into it. As for the air space above the coolant level, pretty much every engine I have experience with that does not have a coolant recovery tank requires a very significant void below the cap sealing surface, some as much as 2-3". I'd suggest as long as the interior tubes/fins are covered, that would be acceptable. At the least you can start at that level and keep a close eye on it.

Was just out playing with bike.
Started bike up, weeped a tiny bit (drops) at waterpump vent hole then stopped.
Buzzed around the street in front of house bike temp was at about 86 Celsius, would go to 90 when stopped then down to about 86 again when moving.
Idled in driveway for min, temp up to 90, shut off bike fan is on for 20 seconds then shuts off and a very faint burp, no steam but I could smell coolant.

So my thought now is....bike is not overheating, but previous owner overfilled rad when prepping bike to sell.
Since it was overfull it was burping and pushing coolant past o-ring or seals in waterpump making bike weep at the vent hole. Also when bike is warmed up with expansion of metal the O-rings where sealing better in waterpump.
Just going ride it and see what happens next before I tear into it.

I bought it online, but I'm sure you can get it from some DSBC sponsor.

Thanks, if problem persists I'll look for some.