Does anyone know the head temperature at which the rear cylinder cuts out at idle? Went up to Perth today to greet my new grandson and as it was hot (37-38degC) i turned on the rear cylinder cutout. On my way home visited Fremantle and had some short runs and long waits at lights. The rear cylinder shut down several times. A bit concerned about the oil. Under 3000km since change and it is brown. Last oil change this didn't happen but weather was reasonably cool for duration. Bike has only done 20k. Most riding is long distance at speed limit with occasional flick to 160kph+ to get shit off liver. Oil is SE syn3. 2013 Ultra Classic.
Just installed Trail Tech temp sensor on rear cylinder spark plug and at 30degC ambient and 110kph it goes to 190degC. Shit that seems hot. 103 twin cam.
Messed around with the head temperature a bit today. 38C ambient.
i let the bike idle until it reached 190C like the ride yesterday. Fired up a small fan I jury rigged to point straight at the rear cylinder head and it was back down to 155C within 4 minutes and 145C in 10. So now I know the various cooling fans available actually do something significant and are probably worth putting on, although I'll fabricate my own system so long as I can make it look good enough for the bike.
I agree Ando. Dunno what the temps would go to on a 40C day giving the bike a bit of curry but certainly much higher than 190C. Good reason to use synthetic oil with its higher temp tolerance than mineral. Obviously there isn't any major issue as the are a ton of Ultras around with serious km on the clock - I know of one towing a trailer around Oz with 175000km on the clock without the engine being pulled apart. I thought that was pretty cool.
I just enjoy the challenge of little engineering projects and all the R&D and experimentation that goes along with it. Its a hobby now but used be my profession. The oil thing fascinates me as at one point I had a bit to do with heat management of oil in automated hydraulic control systems in pretty extreme conditions and along the way learned a fair bit about temperature effect on oils.
There are a variety of tests that can be done to establish oil viscosity. This is one of the best descriptions of viscosity tests and factors affecting viscosity that I have seen http://machinerylubrication.com/Read/411/oil-viscosity. I have never bothered to look at ISO tests of viscosity. My interest was piqued back in the 80's when I developed an automatic ultrasonic depth control system for large agricultural implements and found that hydraulic open centre pumps commonly used in some tractors back then generated enormous amounts of heat with continuous operation at a small percentage of capacity. The effect on oils was sometimes terminal on hydraulic components within days. Did you know for example that automatic transmission fluid, a form of hydraulic oil, fails at less than 800km at a temperature of 165C
By the way my "fucking around like an old mole" generated over $50M dollars of sales, several patents, two technology companies, helped pioneer precision broadacre agriculture and resulted in the first GPS based round and round autosteer system for tractors on the planet. I LOVE fucking around like an old mole as I end up creating new things all the time and improve and modify stuff to suit.
Its one of the very cool things about Harleys. You can buy one and just ride and enjoy it or you can change, modify, customise and improve in more ways than it is possible to count. Have you done a search on Harley Chrome on Google - fuck me there are about 10 zillion hits - awesome.
