I have been out on my GSXR 1000 K5 for a couple of shakedown rides, both with the air temperature around 3 - 4 degrees C. When stationary I warm the bike up first. The temperature behaves as you would expect and fans kick in at 104 F. The bike has had its cooling system flushed, new coolant and a new genuine thermostat. When riding (both rides about 30 miles, all roads including motorways) the digital temperature gauge fluctuates quite quickly between 74 - 82 degrees. It falls faster than it rises. I don’t normally ride when it’s this cold and am wondering if this is normal as the thermostat is cutting in and out or if the coolant temperature sensor is playing up. What’s your experience please? PS. Heated gloves are fantastic!
Are you sure you mean Deg F? Also, where is the temp sensor fitted in relation to the cooling system components?
Normal. My K9 1000 sits at about 78c normally and rises in standing traffic etc then cools back down again quickly, I rarely have the fan come on though unless it’s a red hot day.
My guess is that the stat is probably starting to open soon after 75deg and probably fully open at around 80deg so cooler water from the rad is suddenly finding its way back into the engine causing the gauge to dip and the stat to close which restarts the whole sequence again. I would try riding it one or even two gears lower to raise the revs and generate more heat which should keep the stat open and allow the gauge to hold a more steady reading.
That was exactly my thought Hugh so tried it. Made little difference. Ive done some more research and it may be a ‘thing’ on gixers. I am going to blank half the radiator off and see what happens next. Believe it or not I’ve read that that’s in the workshop manual.
Why did you replace the original thermostat, was it just a precaution during some recommissioning? Also, do you know if the thermostats have their operating temps marked on them, and do you know what the 'correct' range should be for your bike (perhaps a dealer can confirm)? If marked, do you now if original and replacement were the same values? If you have the old one perhaps you could test it by heating it in a pan of water with a thermometer to see if opening/closing temps actually are, might confirm if you have a serviceable spare. Isn't hindsight great!
Replaced as a precautionary measure and also as I couldn’t be arsed testing the old one when a new one isn’t going to break the bank. Both are oe fit for my specific model. I think Hugh has hit the nail on the head - thermostat cycling in low temperatures. Much colder than I would normally ride in but I’ve been bored and I have new heated gloves that need testing along with the bike. So why not!
I had a GSXR1000K2 that did a similar thing, as you say a 'feature' of the model range. Mine was pre-forums so I looked into it - with no change.
Taping off the rad in very cold or wet weather was a standard thing on 2 strokes back in the racing days but if you forgot to take it off when the weather warmed up you usually seized within 2 laps because of overheating.
