Engine Coolant Temperature

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rd84
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Engine Coolant Temperature

#1 Post by rd84 » Sat Aug 05, 2017 5:14 pm

Hi,

I just had my recently restored 1GE dyno' d - the operator said it was running at 90 centigrade on full throttle - he said the racing 2 strokes he normally dynos run at around 60C - is 90C is ok at high power for the RD500? The only modification is a TSA
exhaust system.

Thanks.

Cheers
Paul

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phildu31
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Re: Engine Coolant Temperature

#2 Post by phildu31 » Sat Aug 05, 2017 8:42 pm

Yes, standard temperature. Thermo-contact opens at 105°

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Speed Freak
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Re: Engine Coolant Temperature

#3 Post by Speed Freak » Sun Aug 06, 2017 3:36 am

Thats just the fan switch (105°C on, 98°C off)

The coolant temperature is defined by the thermostat opening tempertature.
= 65°C start of opening, 80°C fully open (thats quite late for a 2-stroke)
I think there is a Suzuki thermostat which opens earlier and fits plug&play to the RD500 (maybe RGV250)

As the RD500 cooling system is known for having a too small radiator I think 90°C on the dyno (how good is the air flow in the cooler on this dyno?) should be OK.


Standard coolant temperatures for 2-strokes are around 60-70°C, 4-strokes ~80-90°C.
Modern car engines are using electrical thermostats which have operating temperatures around 100°C, only in case you are requesting full power from the engine they are opened by electrical heating of the wax element and the temperature goes down to ~90°C.
Just as side info...
My bikes:
RD500 YPVS 1GE
RD350 YPVS 31K 1985
Honda CBR 1000 RR SC57
Yamaha R1 RN04

rd84
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Re: Engine Coolant Temperature

#4 Post by rd84 » Sun Aug 06, 2017 1:43 pm

Thanks for the info. This has put my mind at rest.

Cheers
Paul

begbie
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Re: Engine Coolant Temperature

#5 Post by begbie » Sun Aug 06, 2017 2:59 pm

Hang on ! 90 deg is far to hot for a 2 stroke, what was th AF graph like, have you jetted for the pipe change ? Are you 100% certain the engine is stock ? It maybe over compressed, or running to much advance on a modified (dip switches) stock cdi.
I would not be happy running it at those temps.

silverstrom
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Re: Engine Coolant Temperature

#6 Post by silverstrom » Sun Aug 06, 2017 3:16 pm

Speed Freak wrote:Thats just the fan switch (105°C on, 98°C off)
Is there a different fan switch available? One with lower on/off temperatures?

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Speed Freak
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Re: Engine Coolant Temperature

#7 Post by Speed Freak » Sun Aug 06, 2017 3:43 pm

It`s a standard part which is available with different switching temperatures.
Switching point should be above standard operating temperature, otherwise the cooler fan will run always but it`s not made for it.
My bikes:
RD500 YPVS 1GE
RD350 YPVS 31K 1985
Honda CBR 1000 RR SC57
Yamaha R1 RN04

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tacky1
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Re: Engine Coolant Temperature

#8 Post by tacky1 » Sun Aug 06, 2017 5:17 pm

I remember reading somewhere that a Datsun/Nissan switch will kick the fan in 15 deg lower than the stock fan switch which would be ideal, The RZ/RZV fan on my bikes kick in when its nearly in the red!! Even my older bikes did this, I would prefer them to kick in a little lower..
1985 RZv500
1984 RZ500 Hybrid
1986 RG500 Walter Wolf
1986 RG500 Skoal Bandit
1984 RZ350
1984 RZ350 Hybrid
1981 RD350LC
1981 RD350LC Hybrid
2009 CR500AF Supermoto 250X
2007 CR500AF 250X
1988 YSR50 (2)
1989 VFR750R RC30
1984 GPZ750 Turbo

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Speed Freak
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Re: Engine Coolant Temperature

#9 Post by Speed Freak » Sun Aug 06, 2017 5:43 pm

Some measurements from the German RD350 forum:

Temperature gauge:
85°C = temperature "middle"
60°C = temperature "slightly above cold"
99°C = temperature "one needle width away from red"

=> red is something between 105 and 110°C

Fan switch (80°C on, 75°C off)
https://www.rennsportshop.com/de-top-ma ... C-75C.html" onclick="window.open(this.href);return false;

Thermostat should be RG or RGV250, starts to open around 50°C
My bikes:
RD500 YPVS 1GE
RD350 YPVS 31K 1985
Honda CBR 1000 RR SC57
Yamaha R1 RN04

silverstrom
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Re: Engine Coolant Temperature

#10 Post by silverstrom » Sun Aug 06, 2017 5:51 pm

Speed Freak wrote:

Fan switch (80°C on, 75°C off)
https://www.rennsportshop.com/de-top-ma ... C-75C.html" onclick="window.open(this.href);return false;
Thank you

rd84
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Re: Engine Coolant Temperature

#11 Post by rd84 » Mon Aug 07, 2017 6:00 am

Thanks for the info above - good detail to know.

My 1GE is standard except for the TSA pipes.

My standard 47x as always run at mid scale (suggesting 85C from info above) throughout its life except in heavy traffic on a hot day when it would go to just short of the redline.

I'll try and publish the data when I get the bike back.

Cheers
Paul

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Re: Engine Coolant Temperature

#12 Post by trix » Wed Dec 13, 2017 7:49 pm

just resurrecting an old post as I've been fiddling with a new speedo, trying to get the fuel gauge to read my temperature sensor.
This image shows the temp gauge with the temp sensor in 100degC water.
3/4 way up the main white section was about 94degC.
Middle of the white section in the centre of the gauge was 84~85deg, as suggested above
Quarter way up was about 70degC
With the needle centred in the gap between the initial white block and the main white block the temp was 48degC
It looked like it would need to be about 110 to get it to the start of the red.

Image

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kpke
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Re: Engine Coolant Temperature

#13 Post by kpke » Thu Dec 14, 2017 11:48 am

silverstrom wrote:
Speed Freak wrote:Thats just the fan switch (105°C on, 98°C off)
Is there a different fan switch available? One with lower on/off temperatures?

This switch turns on at a much lower temperature. :smt005

I never liked how hot the bike got before the fan kicked on.


Image
Ken's Garage YouTube Channel :smt023
https://www.youtube.com/c/KensGarage1

1985 RZ500 (R6 suspension & body work)

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