It is weird. There is a fan relay so I'm going to test that too. It's odd that I have both an overheating issue and a fan issue which would kind of point to something more central like the ECU but no idea what would have caused that to happen. Could also be some wiring somewhere that's starting to perish with age maybe?
This is a long shot , disconnect battery for ten minutes then reconnect, start bike don't touch throttle and when fan kicks in flick kill switch off then turn off ignition. This can sometimes reset things . Worth a try Might not work but it might
That has also made me think about something. I already mentioned that I thought I had noticed the temperature being slightly higher than normal at the end of last year. The last thing I changed on the bike were some rear LED indicators and I also changed the relay to support the lower voltage they ran at which could have been around the same time. Seems improbable but I wonder if that has caused this? Possibly it's interrupting the signal for the thermostat to fully open and the fan coming on at the right temperature or some weird shenanigans with the ECU? I'll try the battery disconnect first and if no change I might try swapping the relay back out for the standard one and try.
Has it got 2 fan relays? Low speed and high speed possibly! Put it on the side stand , top it up , put the cap on , run it up (still on side stand) for 2 cycles of the fan, let it completely cool, top it up and repeat.
Just the one relay. Did the reset earlier today.....watching it properly and the fan came on at 115-116C. Will run it again tomorrow to see if the reset made any difference. if not I'm going to swap the relay (there are 4 identical ones) Was looking through a service manual (although it's for a 2004 model as 2006 doesn't seem to exist online) to make sure I hadn't missed something in the procedure for changing coolant and noticed this which I thought was odd as I took a picture of the old thermostat before I removed it and it was in the wrong position according to this and so the new one is also in the wrong position assuming this is still correct for a 2006. Doesn't really explain any of the problems though as it was working fine last year.
IMHO. You wouldn’t think orientation of the bleed hole would be so critical - if it was then you’d expect Mr Honda to have made it such that the thermostat would only sit in the one position
Exactly my thought too. Although I might just move it while how to get to it is still fresh in my mind
I notice that the thermostat has a bypass port shut off plate mounting to the bottom of it. If thermostat isn't aligned properly the bypass port might not be fully closed off which would cause overheating problem as with this port open full flow can't be achieved through the radiator as the coolant just circulates around the cylinder head, for quicker warm up purposes.
follow the honda instruction regarding the bypass hole. At least it is done properly even if it is not your solution
I was always alarmed at how hot my 05 ran. Like you flushed etc. I decided to change the radiator and wow what a difference. Before changing the radiator I also had reason to run mine locally to test things I’d been working on and ran with no fairing. These fairings in these models are snug, it doesn’t take long for temps to rise. However with no fairing there was a very noticeable change in running temps. Best of luck getting to the root of your problem.
View attachment 94183 I was always alarmed at how hot my 05 ran. Like you flushed etc. I decided to change the radiator and wow what a difference. Before changing the radiator I also had reason to run mine locally to test things I’d been working on and ran with no fairing. These fairings in these models are snug, it doesn’t take long for temps to rise. However with no fairing there was a very noticeable change in running temps. Best of luck getting to the root of your problem.
Haven't logged in pretty much since my last post. Holiday, heatwaves and just a general lack of enthusiasm to work on it again until this weekend. I took it apart again. Have now moved the thermostat 90 degrees into the right position (confirmed from pictures in the service manual and Haynes). Also replaced the fan relay just in case and checked the water pump which seemed tight on the bearing and the impellers all look good. Have refilled and ran it once just to circulate and get some of the air out. Going to do one more before putting everything back on. I do have a bit more confidence this time as when I removed the thermostat I noticed that it doesn't sit dead centre (see top down picture below) so it probably wasn't opening/closing fully. Will take it out for a proper test run later to see.
I suspect that the previous owner must have replaced or just removed the thermostat at some point and put it back in the wrong direction. I know he had done quite a bit of work on it including swapping out the radiator so quite probable. Highly doubt that was done at factory and don't think it could have vibrated that far? Maybe last year the bike never really got up to any high temp as I've always just gone for open road rides without being in traffic so it never had a chance to show the problem before? Fingers crossed for the test ride
Not looking too good. Seemed OK in the garage and the fan even kicked in around 106-107C which was a definite improvement. But on the road couldn't get the temp to come down any lower than 95C which is worse than before and when I got back and let it idle on the drive it went up to 120C and the fan didn't kick in until I turned off the ignition and then back on again. Going to let it cool down and settle and check the coolant levels and try taking it out again during the week just to make sure.
