overheating

You can test a ST's cooling system for leaks the same way as you would test an automobile. Go to the auto parts store and borrow a Cooling system pressure tester. Alternately you can get them off ebay. The tester is basically a little hand operated pump with a gauge on it that has on the end of its hose, an adapter for the radiator. You hook up the adapter to the radiator, pressurize the system with the amount of pressure of the radiator cap (14-18psi) and let it sit. If the pressure drops in 10 minutes or less, you have a leak and usually you can hear it hissing from the defective part. If your cooling system checks out OK you can put a different adapter on the tester and test your Radiator cap. You pump up the tester until you hear the cap "pop off" and you confirm that it is doing it at the correct pressure by watching the gauge. The hardest part about using the tool is knowing which adapter you need for each particular radiator or cap. The Stant brand tester, which is the most common one out there, uses a #12027 adapter for the Radiator and #12021 adapter for the cap. I am relatively sure these are the same ones for the 1300 and also some goldwings. Hope this helps.

ST1100Y said:

Possible that this is depending on destination/climate?

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Hmmm, it appears that it is, at least for the years you show. The 2000 USA version is the MR1, while it appears the Euro version is the MT2. This would seem to be relevant for the "when does your fan kick on" threads.

Probably like with tires, varied for northern (colder climate) and south distribution areas...

But the US has a wide variation in climate zones, and it appears all bikes get the same one.

This thread got me to thinking about when the original Ninja 900s were introduced back in 1984-5? they had a problem with running a bit hot. According to one of the m/c mags at the time, Kawis solution to that problem was to solder in a resistor to make the temp gauge read lower.

dwalby said:

But the US has a wide variation in climate zones, and it appears all bikes get the same one.

This thread got me to thinking about when the original Ninja 900s were introduced back in 1984-5? they had a problem with running a bit hot. According to one of the m/c mags at the time, Kawis solution to that problem was to solder in a resistor to make the temp gauge read lower.

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I think my 1992 vfr750 and my 1993cbr900 take the mt2 and run cooler . I have a mt2 and it said 85c

scotboy said:

I think my 1992 vfr750 and my 1993cbr900 take the mt2 and run cooler . I have a mt2 and it said 85c

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So what do you think .put in mt2 to turn the fan on early to keep it cooler when at idle

scotboy said:

So what do you think .put in mt2 to turn the fan on early to keep it cooler when at idle

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Such could impact burning processes and emissions...

ST1100Y said:

Such could impact burning processes and emissions...

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Maybe I am just fishing .I like to run cooler at idle .

scotboy said:

Maybe I am just fishing .I like to run cooler at idle .

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.....to a point, but that's 'old school' thinking(I are one of them). Hotter cyl. temps. are needed for complete conbustion....more so with the fuels of today, along with the different timing curves, etc. that are a whole lot different than decades past.

Brant said:

.....to a point, but that's 'old school' thinking(I are one of them). Hotter cyl. temps. are needed for complete conbustion....more so with the fuels of today, along with the different timing curves, etc. that are a whole lot different than decades past.

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So why does the st1100p 2003 police bike have a 85c and all the st1100 have a 100c themo switch ????

scotboy said:

So why does the st1100p 2003 police bike have a 85c and all the st1100 have a 100c themo switch ????

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My guess is because the Police bikes spend hours a day with the fan on, where the normal rider may cycle the fan a few minutes a day.

Bottom line to me is this is a non-issue. STs run forever with whatever temp switch they have installed, so its not broken and doesn't require fixing. Its your call which switch to run in your bike, but I doubt it makes much difference either way, so do what makes you happy.

I walby said:

My guess is because the Police bikes spend hours a day with the fan on, where the normal rider may cycle the fan a few minutes a day.

Bottom line to me is this is a non-issue. STs run forever with whatever temp switch they have installed, so its not broken and doesn't require fixing. Its your call which switch to run in your bike, but I doubt it makes much difference either way, so do what makes you happy.

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Thanks . I just got the st and it goes to last white mark before red mark and the fan turns on. My vfr and CBR don't get at hot. Thanks again.

scotboy said:

Thanks . I just got the st and it goes to last white mark before red mark and the fan turns on. My vfr and CBR don't get at hot. Thanks again.

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OK, I don't think we heard that mentioned here as yet and THAT is above normal. The fan, in every discussion I've seen, kicks in when the needle is in, or near, the 12 o'clock position. However, you could also have a bad temp sending unit, located on the lower rear of the thermostat housing, giving you a false reading. Try cleaning that connection first. One of those infra red temperature sensors would be helpful to see what your actual temperature is.

I ush said:

OK, I don't think we heard that mentioned here as yet and THAT is above normal. The fan, in every discussion I've seen, kicks in when the needle is in, or near, the 12 o'clock position. However, you could also have a bad temp sending unit, located on the lower rear of the thermostat housing, giving you a false reading. Try cleaning that connection first. One of those infra red temperature sensors would be helpful to see what your actual temperature is.

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Thanks i will check it out

Brant said:

...Hotter cyl. temps. are needed for complete conbustion....more so with the fuels of today...

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I second that thesis, today's fuels are adapted for today's cars, which run a lot leaner, thus burn hotter then combustion engines in the late 80ies and early 90ies...

Bush said:

The fan, in every discussion I've seen, kicks in when the needle is in, or near, the 12 o'clock position. However, you could also have a bad temp sending unit...

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Yep, either the probe or gauge is off, a cause for insufficient coolant flow is present, the air flow through the radiator is decreased, like fins clogged, the propeller has detached from the motor axle, or the fan-motor has an issue...
If the coolant is too low, the temp gauge would bang right out into the red zone, cause the probe sits exposed then, reading steam only...

scotboy said:

Thanks i will check it out

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First thing to check is the coolant level in the radiator itself by removing the rad cap (don't go by the overflow tank).

If that checks out OK then next I'd test the fan switch in a small pan of boiling water on the stove, make sure the switch is actually closing at 100C.

The temp sending unit resistance decreases with increasing temperature, so if you had a dirty connector adding resistance I suspect you'd read cooler instead of hotter, but go ahead and check that connector anyway.

If all of these things check out OK, then you may have a coolant circulation issue. When the coolant spends too much time in the radiator because the flow rate is too low you get a temp gradient between the radiator (cooler, where the fan switch reads) and the temp sensor (hotter, and closer to the engine).

any aftermarket caps and stats available or should i stick to OEM?

oldamigos said:

any aftermarket caps and stats available or should i stick to OEM?

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both are available in aftermarket, but I don't have the part numbers handy to provide, hopefully someone else will post them shortly.

Also, a couple years ago I used the aftermarket parts list and some of the numbers are no longer valid, so don't be surprised if some of them are not available.

dwalby said:

both are available in aftermarket, but I don't have the part numbers handy to provide, hopefully someone else will post them shortly.

Also, a couple years ago I used the aftermarket parts list and some of the numbers are no longer valid, so don't be surprised if some of them are not available.

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Stant Radiator Cap 11233
Stant Thermostat 35868

Both of these work in the ST1100.

Good Luck !

.........also

Radiator cap: 1990-96 Honda Accord 2.2L 16psi
Stant 11233 or 11242
Gates 31336

Thermostat: 1973-80 Honda Civic 1.5L 180 deg
Stant's old number: 35868
Stant's new number: 13868