c3 thermostat vs thermobob for 450 xc

poinrobe · Nov 3, 2018

Currently building up my first snowbike. as mentioned in previous post, the bike is 2016 KTM 450 XC. My understanding is that I need to replace the stock thermostat to achieve optimal performance. what are you recommendations? C3 and Thermobob seem like the options... Thanks

tek9tim · Nov 3, 2018

Raze is another option, and you can easily add their coolant heated handlebars to their setup. Coolant heated bars are the cat's meow. More heat than you need (and adjustable) with zero electrical draw.

My bike had the Thermobob on it when I bought it, and I've managed to plumb in the Raze bars and maintain the regular bypass function of the Thermobob. Need to get it on snow to see how well the whole system does though.

Looking at it logically, you do want a bypass system to make sure the engine is always at the proper temp throughout.

dooman92 · Nov 3, 2018

thermos

Had good luck with two thermobobs, although bypass may be larger than needed on snow. Going to try c3 with coolant heated bars on my 18 500 exc-f. Compact and space is tight. Only downside to raze is they only have a 160 or 170 stat with no other option. That's not warm enough for snow.

Lachoneus · Nov 3, 2018

What is the C3 thermo temp?

you got me wondering now...thanks.

CATSLEDMAN1 · Nov 3, 2018

WELL actually

if you ride a lot of variable snow conditions, in the end its a 190 thermostat and heat exchangers. In my riding group of KTMs a lot of running issues flat went away when we went to more heat and then the way more consistent temps when we ditched the radiators and went to 12" of WAHL Bros heat exchanger.

dooman92 · Nov 3, 2018

I believe c3 is 192 or 195. If one can avoid boil over and constant fan operation 200f would be ideal. I wish I could fit a heat exchanger in my tunnel, I would ditch the rads.

assaultn · Nov 3, 2018

tek9tim said:
Raze is another option, and you can easily add their coolant heated handlebars to their setup. Coolant heated bars are the cat's meow. More heat than you need (and adjustable) with zero electrical draw.

My bike had the Thermobob on it when I bought it, and I've managed to plumb in the Raze bars and maintain the regular bypass function of the Thermobob. Need to get it on snow to see how well the whole system does though.

Looking at it logically, you do want a bypass system to make sure the engine is always at the proper temp throughout.

C3 thermostat has auxiliary ports in it as well to accept heated bars and temp probe.

Throndson · Nov 17, 2018

Ive been looking at the C3 thermostats.
195f(90c)
175f (80c)
Cant decide which one.
I'm Leary about the 195 being to hot in certain conditions.
Anyone have any thoughts for a 450 stock form?

powdermuncher · Nov 17, 2018

C3 bolted straight to the head should be even more accurate than thermobob.

Although my bob works good so I will not change, but on the next new build I will.

needpowder · Nov 17, 2018

powdermuncher said:
C3 bolted straight to the head should be even more accurate than thermobob.

Although my bob works good so I will not change, but on the next new build I will.

I agree. I think my tto on my thermoBob reads 10 to 15° lower than my actual engine temperature is. My fan comes on when it says 170° and I believe the fan is set for 180. I don’t think I would want a 195°F thermostat.

dooman92 · Nov 17, 2018

Temps

needpower, I've been told the Yamahas are more sensitive to temps because the rear of the cylinder (exhaust) run hotter than the front (intake) air flow side. On the dyno cylinder distortion shows up as a power loss at temps above 190. That's why the yami fan comes on at 180. So for the yami, 195 a bit warm for power, but probably good for engine longevity.

As for the other bike engines, I believe the c3 195 is not too hot and is better for engine longevity than 180. Temps above 200 will not damage the engine unless the coolant boils resulting in rapid temp rise at hot spots. So on our bikes boil over is the big threat.

I was an auto tech instructor in the late 70's. We learned the valve of increased engine temps in the 70's with the advent of emission controls. When we went to 195 and 210 thermostats back then everything improved especially engine longevity.

I am going to have a temp gauge on my oil this year. Given the snowbike environment, I suspect the oil runs too cold. Oil film strength is better/stronger at 200 degrees than at 100. Ideal oil temp is over 200. It's gotta be over 212 to boil off moisture and fuel. I suspect our oil runs colder than that and increased coolant temps (195vs180) will help.

needpowder · Nov 18, 2018

Dooman, thanks for that info. Interesting for sure. I guess i wont worry so much when i see higher numbers on warm days as long as im not boiling over.

Snowbikenewbie · Nov 25, 2018

I installed the raze system last year. Kit did not come with a bypass so I asked them for one and they promptly sent one free of charge. I had a hard time keeping temps up even with rads blocked and full engine blanket with cold weather panel. Granted I was lucky to see some super soft powder most riding days. I also noted once I switched to dirt I also had a hard time keeping temps up while cruising enduro in cool spring weather. I just converted back to snow and removed the bypass. I’m hoping to keep temps up around 160 plus this year. Some days last year I was in the 120 range busting pow and trying to keep my hands warm. I was never cold but when the bike stays above the 160 mark the bars are nice and toasty. I’d be interested to hear if anyone else has removed their coolant heated bars bypass due to low temps???

assaultn · Nov 25, 2018

Snowbikenewbie said:
I installed the raze system last year. Kit did not come with a bypass so I asked them for one and they promptly sent one free of charge. I had a hard time keeping temps up even with rads blocked and full engine blanket with cold weather panel. Granted I was lucky to see some super soft powder most riding days. I also noted once I switched to dirt I also had a hard time keeping temps up while cruising enduro in cool spring weather. I just converted back to snow and removed the bypass. I’m hoping to keep temps up around 160 plus this year. Some days last year I was in the 120 range busting pow and trying to keep my hands warm. I was never cold but when the bike stays above the 160 mark the bars are nice and toasty. I’d be interested to hear if anyone else has removed their coolant heated bars bypass due to low temps???

I've played around with this a bit. On average the bars Rob about 15-20deg . Obviously conditions are a huge variable.

Since you mentioned the cold weather panel I'm guessing you are running a PST blanket. Switch to a Revvup blanket with an Obie snow deflector. Seals everything up pretty tight and keeps exhaust heat in. Toasty engine and fingers!!

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c3 thermostat vs thermobob for 450 xc

poinrobe

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tek9tim

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dooman92

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Lachoneus

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CATSLEDMAN1

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dooman92

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assaultn

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Throndson

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