Thermostat Question

Hi Folks

Had the ST for a couple of months now and all seems well, one thing that im looking at is the Thermostat, reason is when im riding the Temp Gauge stays on the first line of the normal range, I think this is not quite right as surely it should be in the middle ish position.

The gauge moves when sitting in traffic or at the lights, and the fan kicks in ok, so am I worrying about nothing?

Just wondering if the thermostat is breaking down.

cheers
chris

caddyman said:

The gauge moves when sitting in traffic or at the lights, and the fan kicks in ok, so am I worrying about nothing?

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Seems normal, as long as you move >50kph/30mph the radiator is quite effective in the now cooler autumnal temps...
How quickly will the needle raise when you start cold and move through town only?

The bike has done 50k

The needle rises as you would expect when sat at the lights, only dips down when on the motorway.

chris

caddyman said:

...only dips down when on the motorway.

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Regular behaviour below/around 10?C/50?F and something like 80mph/130kph...
Just keep revs <2800 in the first 15~20 minutes to allow oil and engine/parts to heat through...

Thanks for the info lads!

If you have to change the stat, the one from an early 80's Honda civic fits and only costs about ?5, compared to maybe ?45 for the bike specific one.

Thanks for that mate, might be worth doing it at that price!!

+1 on the above - normal operation for the ST1100. If you let the bike run on the center stand, the fan should kick in when the gauge reaches about the middle, then turn off after the gauge reading goes down slightly.

IMHO, these bikes may run too cool. One of these days, I may measure the temp when running down the road. The problem with running too cold, is that the oil may be too cool for proper lubricity and it will also decrease gas mileage. IMHO, that's why the later models don't have an oil cooler, not because they don't have the alternator stator mounted in the engine

See "Bob is the Oil Guy" for a good explanation.

Basically the rated viscosity is at 100 C / 212 F . If the oil is much cooler, the actual viscosity is much higher. All oils, even a 5W is way too thick for good lubricity when the bike is cold.

Jim Van said:

Basically the rated viscosity is at 100 C / 212 F . If the oil is much cooler, the actual viscosity is much higher. All oils, even a 5W is way too thick for good lubricity when the bike is cold.

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That's the reason I always let the bike warm up for a few minutes,sometimes you see secondhand bikes that were used as commuters with a lot of engine wear because of so many cold starts and thrashing because they aren't warmed up properly.

Jim Van said:

IMHO, these bikes may run too cool.

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Don't get tricked by a coolant temp gauge...
Once the engine has warmed, the oil-temp might be nicely at 80~110?C/170~230?F, whilst the coolant-temp indicates barely over 45?C/115?F due to low ambient temps...
The water jacket in the engine is quite warmer, but since the thermostat is doing its job flow/circulation stagnates, so radiator and the temp probe in the thermostat housing cooling off due the airflow...
The only real engine temp monitoring would be reading the oil temperature...

The thermostat is a standard automotive one which fits many applications. Here are some numbers I've used:
The thermostat matched a Stant 13868 or Stant Super Stat 45368
Rad cap is part number "Stant #10233" or Stant 11233 Gates part number 31336
'97 Accord temp sender is the same part number

FWIW, the radiator has no effect on the bike's running below the thermostat set point (opening temperature). Until the thermostat reaches the opening point, there is no flow through the thermostat and so no flow through the radiator. One could remove the radiator and substitute some piping with rad neck to attach the cap. I've done this demonstration during our cold weather research, FWIW.

The problem is that the engine isn't producing enough heat to form a thermal gradient at the thermostat opening temperature. This is to say that the heat being lost from the engine into surrounding air is too great for the engine to heat up. The cure would likely be to "tarp in" the front of the bike in order to reduce air cooling of the engine. I'm about to play around with a KLR650 which has an even greater problem in this regards as finally feel like doing something.

I'd suggest, based on extensive cold weather work with automobiles, that covering the oil pan/oil sump to prevent air cooling of the sump would likely allow the engine to reach operating temperature. If diverting air from striking the oil pan of a Civic at 60 mph and minus 60 F will allow the engine to reach operating temperature, then might expect the effect to be sufficient for the ST.

I'm aligned with Jim in the assertion that people tend to run too thick and oil. Somehow the myth that higher oil pressure is a good thing seems to stick despite that pressure indicates resistance to flow rather than increased flow.

Norm said:

Snip ...

I'd suggest, based on extensive cold weather work with automobiles, that covering the oil pan/oil sump to prevent air cooling of the sump would likely allow the engine to reach operating temperature. If diverting air from striking the oil pan of a Civic at 60 mph and minus 60 F will allow the engine to reach operating temperature, then might expect the effect to be sufficient for the ST.

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Good idea/suggestion , IMHO.

I'm also going to try to install a "wing" on the front of my fender to help direct air away from the "hole" under the headlight and to help divert the airflow around my aux lights that are adding drag and lowering my mpg's. If I can reduce the airflow through the radiator, that also may help raise the operating temp.

I got the idea after reading about the Ryno Fender.

Sometimes I just can't believe the "worrying" that goes on here! The ST1100 is one of the most bullet proof motorcycles Honda has ever built because it was so well engineered, better than the 1300, IMO. Are all the worrywarts experiencing real problems with these machines that they seriously need to second guess Honda's engineers?

Bush said:

Sometimes I just can't believe the "worrying" that goes on here! The ST1100 is one of the most bullet proof motorcycles Honda has ever built because it was so well engineered, better than the 1300, IMO. Are all the worrywarts experiencing real problems with these machines that they seriously need to second guess Honda's engineers?

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+1!.........23yr. old scoot here, no electrical or otherwise, THOUGHT needed mod/"upgrade"on mechanical or electrical componenets. Comfort changes(bars,seat,hiway wings) is all that may be needed.....top off with fuel.....ride......repeat.

Bush said:

...The ST1100 is one of the most bullet proof motorcycles Honda has ever built because it was so well engineered...

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Yep... as long as it sees adequate maintenance of course...

Brant said:

+1!.........23yr. old scoot here, no electrical or otherwise, THOUGHT needed mod/"upgrade"on mechanical or electrical componenets. Comfort changes(bars,seat,hiway wings) is all that may be needed.....top off with fuel.....ride......repeat.

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+2 on this! Having had 3 bikes prior to the ST1100, by far this one excels on all fronts. With regular care and maintenance this bike seems to want to go on forever...which is simply fine by me.

Hi Folks, didn't think this post would get so many replies but thanks for them all, im not a person that worries to much about anything as life is farrrrrrrr to short, just like to have a second opinion from time to time!

As for the ST I really like it and rate it in the top three bikes ive owned over the years, and although I still like to tinker with a project bike I do like my everyday bike to be reliable as bump starting a bike at 6am on cold rainy mornings is not my thing these days

cheers
Chris