Recently got around to installing the hotter temperature thermostat on my 2007 919 in an effort to get rid of the infamous exhaust stink.
I based my reasons for doing this install on marylandmike's findings in this thread here [Link]
, hoping that I too would experience less exhaust stink, or even cure it completely!
I purchased the Stant Superstat 45849 thermostat which is rated at 195 degrees Fahrenheit. The stock thermostat is 180 degrees Fahrenheit
My install was slightly more complicated than what marylandmike experienced as seen below:
The stock thermostat (left) and new thermostat (right) - note they are quite different in size:
Using a dremel, I removed small portions of the thermostat at a time to try to get it to fit in the housing, however no matter how much I removed (and I ended up removing a lot more than what marylandmike did) it still would not fit. This was due to the left over casting protrusions inside the thermostat housing getting in the way. Each individual bike may vary on the specific lengths/shapes of the casting pieces.
Casting pieces in the way:
I ended up having to remove the internal casting pieces in the thermostat housing for the new thermostat to fit in. Using a screwdriver and carefully applying leverage to the piece, it bent and then snapped off cleanly.
Once I removed the casting pieces, the thermostat slotted straight in and fit perfectly. I am planning on purchasing another identical thermostat which I haven't removed so much off with the dremel, as I do not want the modified thermostat currently in the bike to fail over time due to the thermostat itself being structurally weaker. With the casting pieces removed, the higher temperature thermostat should fit in without needing to be dremeled down.
Now to the questions...
Here is where I am confused - for the first few days of usage after putting in the higher temperature thermostat, the bike ran hotter (according to my temperature gauge) and the exhaust smell had a noticeable improvement - it wasn't as strong, I was no longer smelling it at stoplights etc. However, after a few days the running temperature of the bike seems to be back to where it was pre-thermostat change - also the fan kicks in earlier than it did previously and the stink smell is back to how it was. Has the bike's computer automatically compensated for the increased temperature and is trying to cool it down sooner? Has topping up the coolant with newer liquid increased it's cooling effectiveness?
Here is a comparison of the temperature gauges before, immediately after the change, and current on my bike. Running temperature = bike has warmed up and riding around without stopping frequently (traffic lights, intersections etc.). Click on the image below to zoom in and see the readings clearer, or right click and select "View image in new tab".