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Does an air/oil cooled bike need a temp gauge?

Discussion in 'Technical and Troubleshooting Torque' started by backmarker, Aug 21, 2009.

  1. I have just started riding a 98 Suzi gsx750f. My previous ride was a gpx250 which was watercooled. Now I'm on an air/oil cooled bike, I have noticed the distinct lack of a temperature gauge.

    Now, with a history of driving heavy vehicles, I'm kind of fond of a temp gauge. The risk of wrecking an engine that will cost $30000+ to replace always kept me interested! So it's a bit of a shock to be riding a bike that doesn't have one!

    What is the risk of overheating an air/oil cooled engine? Does it matter that there is no temp gauge?


  2. Never needed one on my BMW.
    You'll find if the engine does get too hot it will start to ping under load but it won't cook like the water cooled motors.
    Eventually the efi will shut it down but I've ridden in 40+ temperatures in peak hour and the bike doesn't seem to suffer.
  3. A fair selection of wet bikes only have an idiot light these days anyway :roll: Not ideal I agree but your engine will be fine.
  4. So, essentially, a completely different kettle of fish.

    On water-cooled engines there's always the thought of a cracked or warped head, but it sounds like this isn't an issue with air/oil cooled.

  5. Somehow I doubt any engine would be ok with overheating. BMW's even have a warning sticker against stationary revving.

    Why wouldn't a oil/air cooled engine warp its head?
  6. the problem with liquid cooled bikes is the water jacket itself. Over heat the bike and the excess pressure can destroy gaskets, crack engine components put water/coolant into your oil, or if undetected can cause rust to form, which leads to pitting loss of compression etc. Also if the bike gets left out in extreme cold, the resultant ice can cause cracks, and destroy cooling hoses and radiators.

    Air cooled bikes do not have the added risk of the above, that being said they can get hot to a point which can damage internal components, amongst other things.

    Liquid cooled bikes have a greater performance margin, as they constantly and consistently shed heat in a much more efficient way. I.e. you could run flat out at Phillip island a lot longer on a liquid cooled bike than an air cooled engine.
  7. Air/oil cooled engines have higher tolerances that allow for some minor expansion of the metal parts as the engine heats up. As a consequence they are not tuned as highly as a liquid cooled engine, and use a heavier weight oil to maintain lubrication at high temperatures.
  8. Just don't forget to keep the air coolant topped up.
  9. Do you use the left hand or right hand pliers to remove the top?
  10. I find the temperature gauge useful on my Ducati, but only out of interest.

    The Ducati is allowed to get up to 170°C, although I have only seen it up to 146°C on a scorching day when I was stuck in traffic. Believe me, in that situation your legs will cook before the engine has a significant problem.

    There are two temperature sensors on the Ducati. One in the oil cooler, which is used to display the temperature on the dash, and one in the horizontal cylinder head, which is used by the ECU for managing the engine. So the display temperature, which is the one the maximum applies to, isn't even the highest temperature the oil would get to. What is important is to use oil capable of handling those temperatures, and not just any old oil. Oils aint oils in a air cooled engine.

    I'm still using the recommended oil, Shell Advance Ultra 4T 10W-40, which has a Flash Point (COC) of 230°C, a boiling point over 280°C, and an Auto Ignition temperature of greater than 320°C.

    What does all this mean? Well, if you use the right oils, you don't really need a temperature gauge on an air/oil cooled bike.

    Oh yeah, and as Joel says, don't forget to keep the air coolant topped up. Use right hand pliers.
  11. Don't worry, I always keep a bucket of that around the place - with a lid on it, so that it doesn't absorb any moisture.

    By the way, if you store your high compression spark plugs (for diesel use only) in the air coolant, you can double their shelf life.
  12. .. can see it now a gsx750f with a pyro....
  13. Don't worry about the 750f engine. It's basically a milder version of the r-750 engine from the late 80s, ealry 90s and those things used to cop major abuse under racing and were still more reliable than the opposition.

    Just run heavier weight oil in the summer in Australia.