Ktm 450sxf 14 cooling

wwillf01 · Feb 1, 2018

Guys I was surprised at the size of the impeller it had for the coolant... It was plastic and tiny... The circle is what I had the metal one is what I upgraded to via splitstream.... My engine is pretty modified so it is pumping out more heat.. and right now it has been like we are in spring conditions for weeks now... 45 norm temps so I am hoping to cut down on the heat with this...

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needpowder · Feb 2, 2018

That’s definitely good info for people with that bike. Surprised your not running tunnel cooler. The more snow i stop and throw on my engine the more i wonder why i dont just install the cooler that i have sitting in my garage.

wwillf01 · Feb 2, 2018

needpowder said:
That’s definitely good info for people with that bike. Surprised your not running tunnel cooler. The more snow i stop and throw on my engine the more i wonder why i dont just install the cooler that i have sitting in my garage.

Thinking about it... Have qoutes for one but it is such a pain j the butt plumbing wise... Had it on my last bike... Plus attaching it to the camso would take some engineering

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boondocker97 · Feb 2, 2018

Just curious, how big of a tunnel cooler is needed on a snow bike?

M5- · Feb 2, 2018

If you are having overheating problems and it is warm out and you have a Thermobob then the Thermobob bypass may be the problem. The bypass line is too large and allows too much coolant to bypass the rads even when the thermostat is open. The problem surfaces usually in the spring when temps are warmer. What works is adding a valve in the bypass so you can choke off the line and force more fluid to go through the rads. You don't need to shut it off just cut back the flow. If you don't do this then what happens is super hot antifreeze goes right back into your water pump from the bypass and recirculates, the engine cant cool off and temps just build. If you can ride a bike in the sand dunes in 100 degree weather with just rads then you should be able to ride in 45 degrees without boiling.

M5

wwillf01 · Feb 3, 2018

M5- said:
If you are having overheating problems and it is warm out and you have a Thermobob then the Thermobob bypass may be the problem. The bypass line is too large and allows too much coolant to bypass the rads even when the thermostat is open. The problem surfaces usually in the spring when temps are warmer. What works is adding a valve in the bypass so you can choke off the line and force more fluid to go through the rads. You don't need to shut it off just cut back the flow. If you don't do this then what happens is super hot antifreeze goes right back into your water pump from the bypass and recirculates, the engine cant cool off and temps just build. If you can ride a bike in the sand dunes in 100 degree weather with just rads then you should be able to ride in 45 degrees without boiling.

M5

I do have the thermobob Bob 4 so I will look into that
.. the radiators are not crazy hot for sure...

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CATSLEDMAN1 · Feb 4, 2018

COOLER THAN

MY RIDING partner and I bought 2' of 6" wide finned cooler material from WAHL BROS.

We cut into two 12" long coolers, welded up spigots and mounted then in the tunnel on our TS kits just behind the main frame under where your spare gas can would go. 170 degrees on l o n g steep climbs on my 500 xcw, same for Dan's modded SX, he just went to a hotter termo bob and runs right at 185-190 no matter how long and steep. That appears to be plenty of cooling for a 4-500 4 stroke. Tom put the whole 2' under his KX450, same temps, he has lots of cooler.

dooman92 · Feb 4, 2018

CATSLEDMAN1 said:
MY RIDING partner and I bought 2' of 6" wide finned cooler material from WAHL BROS.

We cut into two 12" long coolers, welded up spigots and mounted then in the tunnel on our TS kits just behind the main frame under where your spare gas can would go. 170 degrees on l o n g steep climbs on my 500 xcw, same for Dan's modded SX, he just went to a hotter termo bob and runs right at 185-190 no matter how long and steep. That appears to be plenty of cooling for a 4-500 4 stroke. Tom put the whole 2' under his KX450, same temps, he has lots of cooler.

Any pictures? Is this copper tube with fins like hot water baseboard radiadiant heating?

more snow · Feb 4, 2018

M5, where can I get one of these bypass valves that you refer to for choking the bypass line?

M5- · Feb 5, 2018

I bought mine at Fort Garry which is a truck parts place but any 1/4" ball valve will do. I've seen them at Lowes in the gas fitting section.

I have been playing around with my cooling but I have it nailed right now. Outside temps are just below freezing right now and I am getting dead nuts perfect temps on the trail, 176 degrees. I have a 176 Thermobob with the valve shut down just a little, one rad block completely off and the other open. I was slow to get the second piece of shrouding done on the engine but now I have it and it gave me an instant 25 degree temp increase in the super deep. I am seeing 165 measured at the Thermobob.

M5

Sheetmetalfab · Feb 5, 2018

M5- said:
I bought mine at Fort Garry which is a truck parts place but any 1/4" ball valve will do. I've seen them at Lowes in the gas fitting section.

I have been playing around with my cooling but I have it nailed right now. Outside temps are just below freezing right now and I am getting dead nuts perfect temps on the trail, 176 degrees. I have a 176 Thermobob with the valve shut down just a little, one rad block completely off and the other open. I was slow to get the second piece of shrouding done on the engine but now I have it and it gave me an instant 25 degree temp increase in the super deep. I am seeing 165 measured at the Thermobob.

M5

You have a picture of your shrouding?

CATSLEDMAN1 · Feb 5, 2018

pictures of the heat exchanger

picture here of my heat exchanger when I was welding it up.

this easily cools our KTMs.

One downside I discovered with this set up:

with just radiators if your clutch starts slipping, wow the heat factor sky rockets and you can see 240 degrees right now.

had a slipping clutch on Dan's 450 big bore, temps never varied for water temperature, there is enough heat dissipation with our smallish looking heat exchangers that we never saw water temps rise.

so picture sort of distorts this, finned on the other side, has about a 3/4" flange for mounting along each side, 12" overall length.

When mounted in the tunnel it has about 3/4" clearance with out 2.5" 120 tracks, which is what we wanted, closer you can get the heat exchanger to the track and the thrown snow and wind the better.

kell8071 · Feb 11, 2018

M5- said:
If you are having overheating problems and it is warm out and you have a Thermobob then the Thermobob bypass may be the problem. The bypass line is too large and allows too much coolant to bypass the rads even when the thermostat is open. The problem surfaces usually in the spring when temps are warmer. What works is adding a valve in the bypass so you can choke off the line and force more fluid to go through the rads. You don't need to shut it off just cut back the flow. If you don't do this then what happens is super hot antifreeze goes right back into your water pump from the bypass and recirculates, the engine cant cool off and temps just build. If you can ride a bike in the sand dunes in 100 degree weather with just rads then you should be able to ride in 45 degrees without boiling.

M5

Good to hear you confirm this. I did the same thing on my 13 450sxf and all of a sudden my temps stayed way more consistent and didn't have high temp spikes on the road.

I used one of the ski-doo coolant valves, 420889090 I believe.

Kell

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