KTM 500 EXC cooling system overhaul

[jasbaum]

It's been over a month since I hit a rock on a remote single track in Colorado and split one of my radiator hoses open.

The damaged hose could not be purchased separately -- it and two other hoses are part of a $100 thermostat assembly from KTM. I'm sure I could have found a hose to fit, and replaced only the damaged part, but that would have done nothing to prevent the same thing from happening in the future.

After several weeks of deliberation, I decided to replace all of the hoses, while also deleting the thermostat from the system. Also opted to do a complete cooling system overhaul, even though I wasn't experiencing any overheating issues.

• Samco FTP-4 frame T-piece hose
• Samco KTM-47 hose kit (w/o thermostat)
• Bulletproof radiator guards (replaced previous Unabikers)
• Boyeson WPK-45O supercooler water pump kit
• Evans waterless coolant
• Lower pressure radiator cap
• RLR Products coolant recovery tank (mounts in air box)
• TrailTech radiator fin temperature sensor

If I had to do it again, I wouldn't have bothered replacing the frame T-hose. IMHO, the stock T fitting (made of aluminum) was fine, if not better. And I had to destroy the original to get it out.

Also not sure the switch to waterless coolant will provide any significant benefit, especially for what it costs. But thought I'd give it a try.

Pics should be viewable here: https://goo.gl/photos/eLiYm5tWkFbsmXc28

P.S. Many thanks to the great group of guys I was riding with when the hose split open. I thought sure I would be walking down from the mountain that day, but with everyone's help, we managed to patch the hose and get back on the trail in a relatively short time. And extra thanks to the guys that concurrently fixed the rear flat that I just happened to get at the same time as the broken hose.

[Savage]

How did you patch the hose?

[jasbaum]

Luckily, the split only went half way around the hose, so there was still half of it intact to provide some mechanical strength. Bo had some "self-fusing silicone tape" in his kit (https://www.amazon.com/Permatex-82112-S ... B00X8T3MVY) that he thought would at least hold until we got back to the cabin.

I removed the thermostat housing (which has this and two other hoses "permanently" attached to it with non-removable crimped rings ). The hose is only about 1.25" inches long (part of the reason it split to begin with, as it has no room to flex), and Bo wrapped several layers of the silicon tape around the length of the hose. The end of the tape was further secured by the hose clamp that attached the hose to the engine block.

I thought someone in the group got pictures of the trail-side repair session, but I haven't seen them yet. I was too busy trying to figure out how to get my back back in service to get out my camera.

The repair (mostly) held for the remainder of the trip. After a couple of days, the repair was leaking a little bit, so I avoided any routes that would take us too far from a main road. If I had cleaned the hose better before I had Bo wrap it (maybe with gasoline?), it might not have leaked at all.

I had some of this same tape back in my workshop at home, but had never thought to carry any on my bike (I will from now on). I always had duct tape and electrical tape on the trail, which might have gotten me down off the mountain, but don't think would have held as well or as long as this wonderful stuff did.

Here is a picture of the thermostat assembly, with the damaged hose disconnected, and the repair tape removed. I had to cut off the crimped clamp that attached this hose to the housing. At the top, you can see one of the remaining factory-crimped clamps.


I think the reason KTM used this style of clamp here is because the thermostat housing and its hose fittings are plastic, and it would be easy for and end-user to over-tighten a typical worm-drive clamp, which could deform or break the nipple.

[troy]

While stopped on the trail this past weekend, I asked Bo about his "2017" CO sticker on his Husky. He explained he rode Taylor Park with you guys. He also shared the story of his super tape solution for your broken radiator hose. Definitely some great stuff to put in the kit!

James, an easier, cheaper solution is simply not to crash your bike into trees!

Bo went home Fri night while Sean & I camped...in a flash flood, but that's another story...adventure. In the morning, Bo re-appeared but this time on his brand new KTM 1190 with the stock "dualsport" (street) tires. Bo was amazing on that thing. He crawled right up the muddy, rocky, rutted stuff including one nasty section I failed first attempt. Before taking off that morning, Bo said, "I don't know if I can do it with these tires, but I'm not afraid to try."

[jasbaum]

It's great that you got to ride with Bo last weekend.

And it wasn't a tree I hit this time, but a big rock that was on the inside of a hard ride turn in very tight single track. Had I been just an inch or two to the left, I would have cleared it. Instead, the bottom edge of the radiator guard caught it as I passed. Well, not passed so much as stopped suddenly. Luckily, I was going fairly slow (I'm no Kramer).

[jasbaum]

The other regret that I have about the overhaul was spending the extra money to get the Samco kit that included JCS hose clamps. I wish I had ordered only the hoses.

There is nothing inherently wrong with the JCS clamps that come with the kit. They are high quality, heavy duty clamps with nice rounded edges that won't cut into the hose. Notice the huge difference in the picture below (stock clamps are about 0.6mm thick, 7.5mm wide, and weigh 200mg, while the JCS clamps are a full 1.0mm thick, 12.5mm wide, and weigh 800mg). The JCS clamps are nearly twice the size of the OEM, and weight four times as much. By comparison, the OEM clamps seem like crap (which they, in fact, are).

However, the JCS clamps are almost too heavy duty for the application. Also, the hex head is 7mm, rather than the 6mm of the OEM clamp. No other bolt on my KTM uses a 7mm socket, which means I would have to carry an additional socket in my toolkit. Finally, the clamps are longer than the application needs, so you end up with a pretty long tail hanging out.


I ended up using my ClampTite tool (http://clamptitetools.net/index.php?route=common/home) to create custom-fitted clamps in place using 18 gauge T-304 stainless steel wire.


The result is an extremely strong, neat clamp that weighs next to nothing (it wouldn't even register on my scale).

The only downside to these clamps is that they are not reusable. They are easily removed, if needed, unlike the factory-crimped clamps that KTM uses at the thermostat housing. I plan to pack a couple of spare hose clamps for emergencies. I could pack the ClampTite tool and some wire, but that would not be practical on the trail, as the clamps are not easy to install in tight places.