Sunday, April 8, 2018

Replacing the coolant hoses on a WR250R

Somewhere I read that the coolant hoses should be replaced after about 8 years, or if they show obvious deterioration. Although my bike is a 2008, all the rubber is in excellent condition--including the coolant hoses. However, a trip I'm planning for this summer is has a desert component that's going to stress the cooling system more than it's previously experienced. In anticipation of that, I figured it would be a good idea to replace the hoses with upgraded silicone for increased reliability.

DRC Zeta has a good selection of hoses and other accessories for this bike, although for some reason I was not able to find stock in Canada of the replacement hose kit I needed. I ended up finding an alternative kit from AS3 Performance out of the UK. Shipped to my door it was under $100.

When ordering I was skeptical of the quality, as there's lots of cheap Chinese hoses out there. While some of AS3's other products indeed look like rebranded generic after-market parts, at least these hoses appear to be very well made. The silicone wrap is meticulously even and shiny, with multiple layers of silicone and reinforcing fabric interleaved and no voids--suggesting a careful hand lay-up and heat-treatment. They appear to be far superior to the stock hoses, which are squishy rubber with only one reinforcing layer.

I also noticed that just inside the cut ends of the AS3 hoses, there was an English part number  moulded into the silicone, probably lifted off a number stamped into the mandrel used to make the hoses. I wonder if these parts are in fact made by Viper, a reputable UK manufacturer of silicone hoses for automotive applications. Their video of how hoses are made is fascinating and not at all what I was expecting, considering how much automation exists in manufacturing today.

Fitting the hoses onto my bike was straightforward but required draining the coolant (duh!), and removing the seat, side panels, gas tank, and rear shock (which can be snuck out the left side; you don't need to remove the rear wheel and linkages) to be able to access all the hose clamps. The OEM hose clamps just barely fit over the AS3 hoses; in fact, it was a bit of a struggle to slide the hoses on to some of the fittings. Once tightened down though, there was plenty of clamp thread engaged to keep the hoses secure. Overall the fit was excellent and it took less than 2 hours for the swap. No leaks on a test ride; let's hope they stay that way!

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