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Engine not warming up? Honda NSR150-SP

Discussion in 'Technical and Troubleshooting Torque' started by madlife, Jul 12, 2012.

  1. Hey guys,
    I recently bought a Honda NSR150-SP with 14,000kms on it and it's been great.

    I noticed though that after starting and warming up for 5 minutes, the temperature gauge sat only slightly above cold. Even after riding hard for 20 minutes, at the very most it sat only about 1/6 of the way between cold and hot.

    I thought that it might be a faulty sensor but I checked the temperature of the coolant by sticking my finger in the reservoir located under the seat and it was cold.

    The radiator feels warm but never so hot that I couldn't hold my hand on it.

    I'm not sure whether the temp sensor is located in the radiator or block. If the water pump wasn't circulating the coolant, would it give a false cold reading of the temperature?

    I've stopped riding until I figure out what's going on. Any suggestions or ideas would be very much appreciated.

    Thanks :)
  2. My buddy had one of these. What do you call riding hard? And it is winter.

    If your water pump was not circulating you would have pushed it home.

    A real test would be to let it idle or ride around very slow for 20 mins
  3. Riding hard as in riding backstreets/stop start and running each gear to 9-10k.
    Assuming the water pump was broken, how long would I be riding for before it'd fail?
    The thing I'm worried about is I'm getting lucky each time I've ridden because I'll stop riding just before failure.
  4. Not sure if this is any help but on my 250, the temperature gauge never moves very far unless you ride it really hard then get into stop-start traffic. It only got hot enough for the fan to start up about three times.
  5. Let it idle for 30 minutes or so and check the gauge, in riding it around your actually cooling it at the same time, if you idle it then it will heat up without air affecting it.

    When the bike is hot, carefully and slowly... Carefully and slowly.... Release te radiator cap and check if it's hot in there. I doubt there is a water pump issue due to the fact that it's not overheating... If you can locate your temp sensor run a test on it and make sure it's actually working, if that is faulty then it's going to display the incorrect temperature on your tacho.

    A lot of bikes will not run that hot due to the sheer fact it's winter. My spadas needle does not rise that much either, maybe it's a design of the bike, have you checked on another bike if it's the same?.
  6. Is the thermostat faulty ( stuck open ) or has it been removed???

    from the manual.

    Engine temperature too low
    • Faulty temperature gauge or thermo sensor (Section 18)
    • Thermostat stuck open
  7. I think that the NSR doesn't have a thermostat, I read that the manual was a copy paste from another bikes manual? This could be incorrect though.
    I have a copy of that manual but it doesn't include a section 18 so I cant read anymore on it. Do you have section 18 by any chance?

  8. Sounds promising... Geez sometimes you forget the simple things lol
  9. Must be the same manual....finishes at section 17.

    A thermostat would be in the return hose between the cylinder head and the radiator inlet ant the top of the radiator.

    If there is no thermostat, then that may also explain the low operating temperatures.

    That said, be careful to warm the bike up before setting off as you could just as easily have a 'cold seizure'. ie a cold engine has smaller tolerances than optimum tolerances @ proper operating temperature...explained another way cold metals contract in size, hot metals expand. Somewhere between the 2 extremes is the ideal operating temperature where pistion/rings and cylinder at a temperature are at optimum size to work together.

    If your interested, there is a thermostat system devised for the GP bikes which could be fitted to a NSR150. They are not cheap though...( US site, temperatures mentioned are in Fahrenheit, 130F is about 55C )

  10. as far as i know it would have to have a thermostat and there designed that if there fail there stay open
  11. Don't what's happening with this thread but i thought i would reply because it might help someone else.
    As far as i know they do not have a thermostat. (I ride an NSR150SP, replaced piston rings a couple of times and changed an engine)
    My bike never goes above about 1/6 of the way up the gauge unless i am sitting in traffic in summer.
    The temperature sensor is on the top of the cylinder head.
    These bikes always take a while to warm up, especially in winter. I usually give my bike around 10min before i start riding if it's a cold morning. And remember to turn off the choke or it will never warm up properly.
  12. Hey mate,
    Thanks for the reply. My NSR was exactly the same.
    It kept running while I had it and I never had any issues.
    I have since sold my NSR and got an Eliminator, no temperature gauge to scare me on it!
    Thanks again