The past 2 days I noticed my engine is running significantly hotter then on Sofie's bike (+- 2 bars on the temp indicator). It also warns up faster then here. Doesn't overheat, but in stead of keeping the engine temp sorry of half way the indicator bars it now stays around 1-2 bars below the lowest point of that little triangle the dash makes. I have a few theories but want to hear your opinions without already biasing the responses in certain directions. So would love to hear your thoughts.
Thermostat is one of my suspects as well. But I'm not sure the engine would warm up as dat as it does in that case. It would explain why it stays hotter than usual though.
cooling problems are annoying. If the coolant level is dropping it will be the crap intermittent cap or a kink in the redraw hose, when cold you might hear a vacuum pop when removing the cap. If you dont hear this the redraw hose might have an air leak. From memory i think the Tstat on these bikes works in reverse to allow coolant to flow around the block only, when warming. An advantage of the built-in radiator tstat where the "in & out" are close together. Nonetheless it could still be the problem. Weep hole dry? Oil clear? Cap rating?
TR650 Thermostat is OPEN when COLD and CLOSED when HOT and it is in the right hand side of the radiator, not on the engine block as in other bikes. Due to the design and strength of the spring the thermostat often does not Close fully at operating temperature and it results in a loss of Radiator efficiency leading to higher running temperatures. I would go for a Thermostat delete for all TR650s except those that are run in freezing conditions. DIY job takes less than an hour and cost is minimal if you use a baffle in the original cage.
Finally found time to look at the issue today. To be honest, I didn't expect it to be a cooling system issue. Mainly because the problem seemed to occur more pronounced at lower revs and the bike was more economical on fuel. I suspects a fuelling issue (lean running at certain revs) so was more planning to look at o2 sensor or valves. But nevertheless checked the radiator, cap and overflow reservoir first. The reservoir was very full and the level in the radiator was very low. So I looked for a kink in the lead. There was a small kink which didn't look like it would cause problems, but I rerouted the lead and went for a ride. All back to normal now. Thanks for all your input!
The full reservoir is indicative of the Radiator Cap fault that has occurred on so many TR650s. When system pressure rises above 1.2 bar it overcomes the cap spring and coolant passes from the radiator up into the expansion reservoir. Upon cooling the coolant in the reservoir should then pass by vacuum and gravity back down into the radiator via the small black button valve in the centre of the cap. Often this small valve sticks or gets blocked and the coolant remains up in the reservoir. Next time the bike is run it gets hotter and more coolant passes upwards, eventually overflowing the reservoir and the bike overheats. The remedy is simple, with a cold engine, take off the radiator cap and carefully prise open the small black button valve a few mm. Wash this under a tap or hose to clean out any residues that may cause it to stick. Make sure the black button springs back into place easily. Top up the radiator until full and run the engine for 30 seconds with the cap off to expel all air from the system. Stop engine and make sure radiator is 100% full, replace the cap. Add 100 ml of coolant to the reservoir and all should be good.
Or buy a new decent cap, $10. Standard issue caps are crap, Proven. I have flushed the coolant 3 times in 4 years. And still what appears to be little flecks of black paint still contaminate the expansion bottle. I guess from the manufacturing process?. I can see it because my waterless coolant is clear. And other have mentioned a black sludge
Thanks for the additional info. I have already cleaned the cap and switched it over with Sofie's bike. If the problem re-occurs on her bike, I'll know the cap is at fault. Benefit of riding 2 identical bikes. But it was probably just the kink in the hose. The pressure from the radiator overflow pushed the fluid past the kink, but gravity wasn't enough to make it flow back.
