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  4. What should the temp meter show, really?

What should the temp meter show, really?

Scheduled Pinned Locked Moved Engine
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  • Hark_PtooieH Offline
    Hark_PtooieH Offline
    Hark_Ptooie
    wrote on last edited by
    #1

    My engine seems to run cold. The needle is barely over the minimum, like 20% the distance to red. When I am idling for a while it rises a little and gets to like 25-30%.

    I don't remember what it used to be like on my last DTR back in 1999, but my DTLC definitely used to be at 50% most of the time. When it did not overheat on some motocross track.

    S HOTSHOT IIIH 2 Replies Last reply
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    • CalumC Offline
      CalumC Offline
      Calum
      wrote on last edited by
      #2

      Sounds like the thermostat has been removed. Normally older DTRs run 3/4 way up IIRC.

      I only had an RE which just had an overheating light....

      Always Originate, Never Pirate!

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      • Hark_PtooieH Hark_Ptooie

        My engine seems to run cold. The needle is barely over the minimum, like 20% the distance to red. When I am idling for a while it rises a little and gets to like 25-30%.

        I don't remember what it used to be like on my last DTR back in 1999, but my DTLC definitely used to be at 50% most of the time. When it did not overheat on some motocross track.

        S Offline
        S Offline
        SpookDog
        wrote on last edited by SpookDog
        #3

        @Hark_Ptooie

        Mine is about 1/2cm over the C in hot summer. If it creeps anywhere near towards the middle I pull over and check the radiator level. In the winter it barely crawls above it. Tried multiple thermostats and a few different senders. All the same…

        I plan on adjusting the needle with a resister one day, cause it used to bug the fux out of me 🙂 …

        PS: I have an 1988 bike. I don’t think anything really changed until they did away with the gauge and put in an idiot light…

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        • R Offline
          R Offline
          R3L3_89
          wrote on last edited by R3L3_89
          #4

          Mine's the same, runs about 1/4 of the gauge at max with no issues. You should avoid revving too high while the needle is still in the thin green line but don't let it idle for too long, it's generally a bad idea for 2 strokes. Depending on your mixture, the engine is warmed up when you see significantly less smoke coming out of the exhaust, trying to slam high RPMs in lower gears when it's cold will create misfires and janky throttle response.

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          • Hark_PtooieH Hark_Ptooie

            My engine seems to run cold. The needle is barely over the minimum, like 20% the distance to red. When I am idling for a while it rises a little and gets to like 25-30%.

            I don't remember what it used to be like on my last DTR back in 1999, but my DTLC definitely used to be at 50% most of the time. When it did not overheat on some motocross track.

            HOTSHOT IIIH Offline
            HOTSHOT IIIH Offline
            HOTSHOT III
            wrote on last edited by
            #5

            @Hark_Ptooie said in What should the temp meter show, really?:

            My engine seems to run cold. The needle is barely over the minimum, like 20% the distance to red. When I am idling for a while it rises a little and gets to like 25-30%.

            This sounds pretty normal. During road riding even in summer my temp gauge never went beyond about 1/3 into the thick green scale.

            Off-road though it's a different story, the temp gauge really illustrates the limitations of Yamaha cheapening the excellent DT200R 3ET twin radiator/2T-oil-in-frame design to create the DT125R. Near where I live there is a Right of Way with a long steep hill where the farmer has installed a lot of concrete speed humps to prevent soil erosion and slow down 4x4s (use your imagination). Up here in 3rd/4th gear and lots of revs the temp gauge quickly goes up to around 75%. Once at the top where it's flat I always used to put the bike in a high gear so it approached road speeds at very low rpm and the temperature came back down almost as quickly. If I'd carried on riding I was considering getting a couple of 12V fans, making a bracket and wiring in a manual switch from the battery.

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            • Hark_PtooieH Offline
              Hark_PtooieH Offline
              Hark_Ptooie
              wrote on last edited by
              #6

              Okay, I shall stop worrying.

              Thanks, all!

              S 1 Reply Last reply
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              • Hark_PtooieH Hark_Ptooie

                Okay, I shall stop worrying.

                Thanks, all!

                S Offline
                S Offline
                SpookDog
                wrote on last edited by
                #7

                I think the gauge is pretty useless. My barrel heat seized before it ever reached the red! If it’s not giving usable information it’s no good.
                I can’t remember exactly but I think the thermostat opens about 65* so that should be the ‘normal’ point on the gauge (dead centre) 85* should be ‘high green’ and 100* should be entering red…

                It’d be easy enough to change the needle position using a potentiometer (variable resistor) Once it’s in the proper place read it with a multimeter and solder in the relevant resistor to adjust…

                You’d have to do it ‘out of the bike’ though.
                Put the temp sensor into a bowl of water heated to the relevant temp (use a thermometer) of 65, 85 & 100 and adjust the needle till you’re happy.
                You’d have to remove the rev counter gauge and make a curcuit with a 12v battery…

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