[kosta212]

My 650 naked runs great but a bit hot. can I swap out a sv 1000 radiator or say a gsxr 600 radiator? or any other fix recommended. Just had bike tuned and oil changed.

 

[AJ711]

Are you just driving it on the street? How old is the coolant? Stop and go traffic or freeway driving? High revs or just cruising?

I see temps around 185 when I'm at a decent cruising speed. However, stop and go traffic sees me up around the fan settings (211-217 or so). Are you riding the crap out of the bike? Constantly in high RPMs?

There is a lot that goes into needing a better cooling system.

AJ

 

[kosta212]

recent road trip, open road, temp never below 190, 6th gear cruising 75 mph. city riding (Manhattan) temp always 215+. Read somewhere temp shouldn't be too much over 200 if at all

 

[VetteV12]

I would say stuck thermostat or somthing blocking the water flow. My SVS runs around 170ish doing 75mph in 6th in 100* wheather. City crusin at 40mph around 180 or so, if it's just sitting it'll climb to around 215 and then drop to 190 after the fan kicks on.

 

[Zanetti]

The thermostat regulates coolant temp to 190F. It's normal to see the temp rise above this during transitional speed and power changes. Unless the temp goes above 220 and stays there, consider it normal operation. Remember, an engine that runs cooler than normal (in this case 190) is just as bad for longevity as an engine that runs hotter than normal.

Edit: If you're really concerned about it running hot, changing the thermostat (possibly to one rated 10 degrees cooler) would be the first logical step. Fitting a larger radiator won't help.

 

[AJ711]

The fan turns on at 217 and off at 211 degrees F. To see 215 during city traffic is not uncommon when I'm stuck commuting to work.

What Zanetti said is true as well. A larger radiator won't help as much as putting a colder thermostat in, or adding a bottle of Water Wetter to the coolant mix. A vendor in the car forums did a review about a colder thermostat vs. colder t-stat + water wetter vs. larger radiator and found the colder t-stat with addittive had a quicker return time to NOT than any of the others.

You might have old coolant as well. The heat transfer properties of the coolant get worse as it ages. Unsure of the age/mileage of yours, but maybe a flush is in order.

AJ

 

[wonderjosh]

during the summer you can use redline water wetter and it will run a bit cooler... just remember to change back to antifreeze before the winter

 

[andyauger]

There's a lot of misinformation in this thread. What you see on the temperature gauge is the temperature of the coolant going back to the engine. Hot coolant enters the bottom of the radiator and cools as it rises. The return line is at the top. The thermostat opens in response to the temperature of the coolant in the engine. Most thermostats have small bleed ports that allow some coolant to pass so the temperature at the thermostat is closer to engine coolant temperature.

If you are running at a constant rate on the highway the thermostat will open and close regularly. There's plenty of air flow, so the coolant stays at a relatively constant temperature. In city riding the temperatures tend to fluctuate and may rise until the fan kicks in. When you're stopped with no fan the coolant temperature rises quickly. When you are between stoplights (or whatever else is impeding your travel) the air flow increases. The coolant temperature in the radiator drops.

None of this says what the temperature in the engine is. A 190 degree thermostat is fine. Also, putting in a colder thermostat may lead to drivability problems and rapid carbon buildup in the heads. Removing the thermostat completely can cause overheating because there isn't enough "residence time" for the coolant in the radiator. 217 F for the fan to kick in is no reason to be concerned. Variations in temperature readings from bike to bike is more a function of how difficult it is to measure temperature accurately with relatively cheap instrumentation than in actual running differences.

If the fan kicks on occasionally in stop and go traffic, and if it stays off other times, then don't worry about the temperature indication. Just worry if it rises and keeps on going higher with the fan on.