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Oracle

Opinions wanted on thermostat bypass

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I'm thinking about installing the aftermarket radiator hose kit, with thermostat bypass, on my 08 ktm 530. I'm interested in opinions and comments on this subject. The good, the bad, etc...

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Thermostat is probably more necessary in the colder climates. If you do take it off make sure to warm it up before putting a load on the motor.

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Dont know if your bike falls into this category but on some cooling systems the thermostat is also a basic flow restrictor that reduces the velocity of the coolant in the system and keeps presure higher in critical areas.

"The secret of the thermostat lies in the small cylinder located on the engine-side of the device. This cylinder is filled with a wax that begins to melt at around 180 F (different thermostats open at different temperatures, but 180 F is a common one). A rod connected to the valve presses into this wax. When the wax melts, it expands significantly, pushing the rod out of the cylinder and opening the valve.

It's amazing how many people think the thermostat's main function is to keep the engine cool by regulating the amount of coolant through the radiator. More importantly it prevents the engine from running too cold. It allows the engine to heat up quickly after start up and to keep it at constant operating temperature minimizing cold running where accelerated engine wear occurs. Another lesser known fact is that it also acts as a restrictor to bring up the boiling point of the coolant inside the engine. But not so that it restricts flow enough to induce hot spots. It's a poor practice to remove the thermostat on a street car when fighting overheating problems"

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Its fine, none of the offroad only bikes have them. The only issue would be running down the hwy on a really cold day, would be better to have it in there in that situation to keep the engine temp up to normal operating temp. Its there to keep the engine warm not cool.

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What Spaugh said-

If you look at the race versions (SX for example) of most of the bikes they dont use all the thermo plumbing. Thats an indication that for all intents and purposes its not a necessary item, its geared for use with DOT vehicles (which the euro bike E versions are) But even in the racing enduro classes the race teams are running straight hose kits without a mechanical thermostat. Mech thermosats are failure points in the eyes (of me) most race teams. Just use sense like stated above, give the machine a moment to warm up then go after it!!

My 250EXC KTM had one- Huskys TE450 had one-TXC450 had one-TE310 had one-TXC310R had one-TE300 had one , all were removed and replaced with hoses only with zero issues.

The Husky TE310 and TXC310R retained their in line fan thermo switches for auto fan on function, with my ex TXC310R (now REV5 bike) also having a manual fan switch installed in parallel with the thermo auto switch.

PS CV4 and SAMCO both make high quality hose kits and you can bling it with color too!!

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Its fine, none of the offroad only bikes have them. The only issue would be running down the hwy on a really cold day, would be better to have it in there in that situation to keep the engine temp up to normal operating temp. Its there to keep the engine warm not cool.

Agreed- but...

I'm less concerned about perfect operating temp on a carbed bike than an FI bike. And I've never had a thermostat fail (on my previous bike, everything else did) so I'm keeping mine on the 500 for now.

But I'm still tempted.

Simpler = better. That's my moto.

(Bob, you saw what I did there, didn't you?)

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When I first got my 08 530 it had heating problems. The fan would run too much and kill the battery, and it was hard starting. I wanted to get the hose kit but didn't have the $$$ so I worked on the starting issue first... It took three tries to get the jetting right, but now it never overheats and it starts instantly at 6000ft or at sea level, with frost on the seat or at 100 deg.

If your problem is overheating, you might start in the carb. just my thoughts

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Thanks for all the input. It's pretty much what I wanted to hear, and expected, for that matter.

My bike has never had an overheating issue....even with a crushed right radiator....so...since I'm replacing the right side radiator, I'm going to install the after market hose kit and some Devol radiator braces too....

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Oracle, I also had a 2008 EXC 530. It would overheat on slow single track at elevation. I have an Acerbis 3.2 gallon gas tank so the KTM OEM fan kit did not work.

To overcome I built my own fan kit using 2 computer fans, a switch, fuse, intercooler cable ties and a thermostat. Each computer fan (25mm thick by 100mm square)was mounted to each radiator with the intercooler cable ties. The fans were wired to the thermostat, a switch on the frame, the fuse, then to the battery. Use a 1A in-line fuse for safety. I can lookup the thermostat p/n I used if needed(I purchased from NAPA). The fans lasted for ~2 years before replacement, but they are inexpensive. Also I have used them in wet conditions, but they are not sealed/water-proof. The fans were purchased from Fry's in San Marco's, they have a large selection. Get the fan with the highest CFM flow rate.

After installing the fans the bike never overheated.

Good luck with it, good idea with the DEVOL braces (the KTM radiators I'm sure are quite costly) and I agree with the others, get the jetting right 1st(JDI kit).

Also I know some guys use aftermarket coolant sure as Evans or Engine Ice with good results.

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Oracle, I also had a 2008 EXC 530. It would overheat on slow single track at elevation. I have an Acerbis 3.2 gallon gas tank so the KTM OEM fan kit did not work.

To overcome I built my own fan kit using 2 computer fans, a switch, fuse, intercooler cable ties and a thermostat. Each computer fan (25mm thick by 100mm square)was mounted to each radiator with the intercooler cable ties. The fans were wired to the thermostat, a switch on the frame, the fuse, then to the battery. Use a 1A in-line fuse for safety. I can lookup the thermostat p/n I used if needed(I purchased from NAPA). The fans lasted for ~2 years before replacement, but they are inexpensive. Also I have used them in wet conditions, but they are not sealed/water-proof. The fans were purchased from Fry's in San Marco's, they have a large selection. Get the fan with the highest CFM flow rate.

After installing the fans the bike never overheated.

Good luck with it, good idea with the DEVOL braces (the KTM radiators I'm sure are quite costly) and I agree with the others, get the jetting right 1st(JDI kit).

Also I know some guys use aftermarket coolant sure as Evans or Engine Ice with good results.

Thanks for the info. That's a great idea and thinking outside of the box for sure. I'm running a Acerbis 3.4 tank and I have a factory fan on the bike, which works fine. Like I said, I haven't had overheating problems, just have heard the stories and want my bike set up the best possible way to prevent that from happening.

I stock OEM radiator is about $261 from most part houses. I found a guy parting out a 530 and I picked up the right side radiator, in perfect condition, for $100.

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Also I know some guys use aftermarket coolant sure as Evans or Engine Ice with good results.

Evans will prevent coolant loss via radiator overflow.

It will not, however, reduce operating temp nor prevent overheating- only the obvious evidence thereof.

Proceed with caution.

Engine Ice is a very different product- much more like "regular" coolant.

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If you don't mind, I would like to give my 2 cents. With out the thermostat there is nothing to restrict the coolant flow which will not allow for proper heat transfer. Long story short, me and my buddy riding up White Mountain at big bear during the big bear run. We have the same bikes, both running Evans waterless coolant. He has the hoses that eliminate the thermostat, mine is factory with thermostat. His F/I light was blinking while mine was fine. Both have electric fans, and both working. Im sure my bike was pretty hot but not hot enough to set of the fault indicator.

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Paul- off coarse I saw what you did there...I do agree that if less can go wrong, remove it. Like others have said; it's to HEAT the bike faster, not cool it down. Not usually a huge problem in SoCal, even the mountains where I live

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EKN - interesting. With all the sensors, etc related to each other, some things don't work well if one signal is removed. I don't know the bikes well enough but I always remember a Toyota truck I had that would not shift out of 2nd gear (auto) until very warm and would sometimes shift back into 2nd - usually at speed on the freeway. I thought I was looking at an expansive trans fix but turns out the thermostat was stuck partway open/closed. The truck did not maintain proper temps and it's sensor told the transmission it needed more RPM's to heat up. $15 later and I a smooth shifting trans.

Don't know if this thinking transfers to the current topic, but..............

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Well, over the weekend I replaced the trashed right side radiator, installed some Devol radiators guards, and installed the Pro Factory radiator hi-flow hose kit with thermostat bypass. Also did an oil change, spark plug, and grips...the 530 is ready to rip. I'll be doing a hot lap around my local stuff later this week to test everything.

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Rmember if it aint broke, _________it. You fill in the blanks. As long as you know the flow rate in all the different areas of the cooling system are right, you should be good to go.

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Rj at All American KTM, told me that in our climate the thermostat......more designed for the ALPS.....was not necessary and removing it , can in fact help with overheating.....

so when I was having other work done, I had them remove it.....I haven't seen any difference in the bike.......I DO NOT ever choose to ride in the freezing cold, and will avoid that in most cases......

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