Last weekend was a relative scorcher in the northeast for late April. Temps were over 90 degrees for several days, with highs usually in the high 60s to low 70s normal for this time of year.
I took my 1300 Voyager up into Vermont for a nice Saturday ride and noticed the bike was running a bit hotter than normal. While in stop-and-go traffic, it actually turned on the overheat warning light on the dash a couple times. The bike has always run on the warm side, but it seemed to be running consistently one bar higher on the gauge than it did last year. It was time to address the problem before the summer heat really hit us.
After checking for the usual things, proper coolant level and no air in the system, I tried removing the radiator grille to see what effect that would have, but there was no noticeable change. I decided removing the thermostat would allow constant coolant flow through the radiator, and eliminate the restriction in the system.
I drained and removed the radiator, removed the water pump impeller cover and bypass tube, then removed the thermostat housing and thermostat. While I had it out, I checked the operation of the thermostat and found it to be opening at a little higher temp than the manual called out (78-86 degrees C). I took the thermostat and spring and threw them in the spare parts box. Done. But I had one more issue to address.
The 1300 has a bypass tube that allows coolant to bypass back to the engine when the thermostat is closed. The thermostat also has a feature on it that when the thermostat opens, there is a valve that blocks of the bypass tube, allowing all coolant to be routed through the radiator for cooling. Removing the thermostat allows coolant to constantly bypass the radiator, degrading the cooling. My solution was to insert a simple disc made of stainless steel, cut from a piece of .025” sheet, just above the bypass tube into the thermostat housing. The disc is “captured” in between the tube and the housing, and will completely block off all bypass flow. The result is that 100% of the coolant is routed to the radiator, with no restrictions.
I re-assembled the bike, refilled the radiator and took it for a ride. The bike now consistently runs 2 bars cooler on the gauge, and the cooling fan only comes on now when stuck in traffic. There is no noticeable difference in how the bike runs when cold. I am planning to take a trip out to Colorado this summer, and was concerned about how the bike would handle the trip across the plains in the heat of the summer. I believe this will prevent any temperature issues on the 1300 Voyager.
