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Discussion Starter · #1 ·
Hey folks,

Wanna see if my bike acts like yours.

Been riding my K4 750 around, and lately it's been pretty cool up here in the northwest. I am usually riding in mid 30's to mid 40's right now. About as cold as I would ride, and it's nice and dry for once. First winter with this bike.

Anyway, on the freeway my coolant seems to hold low 160's or so in these temps. When it was warmer, I was seeing more like 175-180F on the gauge on the freeway, but now I am seeing 160-165 on the freeway. Never drops below 160F once it has warmed up to at least that much.

In stop and go it gets up to the normal temps, fan comes on, all that jazz.
Bike rides great, and has a brand new thermostat. Very inclined to think it is working correctly. Running Engine Ice, and coolant system has no leaks and is bled right.

Is it normal for it to just run a bit cooler in the colder months? Is that what you guys have seen? Just takes quite a while to warm up when I get on the freeway in the morning. Should I make a partial radiator block for riding in the mid 30's, or does the engine just not care that much and I am just overthinking?

Thanks in advance.
-Mike
 

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it should be up to full operating temp, if not your thermostat is prolly off, the thermostat holds the coolant back until it reaches temp, or close to, any chance someone has put a cooler or colder thermostat in er?

you can remove and boil with temp gauge in the pot see what temp she opens at?
 

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Discussion Starter · #3 ·
The 18 year old thermostat I took out and just replaced it with a brand new unit for peace of mind. The stock unit is 190F, and I put it in myself with the shop manual.

I mean, even if it's fully closed, the bypass allows an amount of coolant through anyway, could that be cooling the engine a lot? Could my ECT sensor just be off a bit and read lower than it actually is? Although I don't think that is the case, because the radiator fan is supposed to kick in at 221F, and mine kicks in at indicated 219F, so I'd think the ECT is within a few degrees.

Also, even though the thermostat is 190F, it doesn't sit at 190F on the freeway even in the warmer weather.

Haven't looked for other temp thermostats, but I still don't think my brand new one is malfunctioning, but I am wondering if the behavior I am seeing is normal.

The service manual says if the engine "overcools due to extremely cold weather, to install a radiator cover". Is 35 degree weather "extremely cold weather"? Once i hit traffic and heat up the coolant a bit more, it does sit right around 180-220 until I pick up enough speed.

-Mike
 

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I agree with Suzuki. It's running too cold if it won't stay at or above 170 °F. You should be able to rig up a piece of cardboard that blocks half of the radiator. It will be cheap enough that you can tear it out and toss it if the temps should start going up. Ideally the carboard is shaped to not cover the section of the radiator where the fan sits (on the other side).

Condensation is going to start building up at low temps. Unless it periodically gets above 212 °F, let the bike idle once you're home till the temp gets there to boil out any water.
 

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Discussion Starter · #5 ·
Good call, thanks for the input. I have been researching this, and there seems to be little to no discussion on this topic. A lot of people with Ducatis seem to have this issue way more extreme than I do, they were trying to cover their radiators because it was like 50F outside, and their bikes were running at like 140F coolant temp...

Regardless, yeah it sounded like the appropriate time to use the cardboard, it's just probably intentionally vague in the manual for when to use it.

This evening I rode home from work, with plenty of stop-go in the beginning and got my fans on multiple times up to 220F, and then since it was warmer in the evening, I was able to hold 170 on the freeway on the way home, but it was maybe 10 degrees warmer on the way back. I would think I am burning off the condensation plenty on my rides, they are usually long enough and varied enough I would think that isn't an issue in my case.

I think I will make an easily removable blocker on the left side of the radiator like you said, so the fan can still operate. Maybe I'll experiment with a few size panels as well.

Any more input would be appreciated, thanks Bill!

-Mike
 

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Discussion Starter · #7 ·
I guess 160 isn't too far off from 170, but 160 does feel kinda far from the thermostat's specified 190 opening temp.

Regardless, as an experiment, I blocked half the radiator off with cardboard this morning on my ride in to work. It was about 32F at the house, and maybe 35F at the office. On the freeway at the beginning, the engine came up to 180F at a rate I would expect in the summer, and held nicely. Once I hit the city traffic, I had the radiator fan come on maybe 2 or 3 times before I finally rolled into the office. Temps never exceeded 220, and in the stop and go, I was usually seeing 190-200. The fan was still quite able to cool the coolant, when the fan kicked in it would drop from 220 to about 208 or so pretty rapidly.

I mean, these results sound pretty good to me. Anyone wanna weigh in on that? I might trim the radiator block to expose slightly more radiator to keep temps in the city slightly down, but also I don't really often drive my sportbikes through town other than commuting. Some rides in the twisties earlier this winter the bike struggled to get hot as well, so maybe the amount I've covered is actually good for the type of riding I am doing.

Maybe I will design a dynamic radiator cover, would be fun and put the tooling at the office to good use.

Thoughts?
-Mike

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I'm running at 157 in 35f weather. I use Water Wetter as well.
 

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if you need a cover you have something else wrong, againthe thermostat holds back the water till its up to temp, if too much is getting by and its not warming up toss a new thermostat into it, why would you be the only one having this issue? these bikes are dead nut, its telling you something..
 

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Discussion Starter · #10 ·
I'm running at 157 in 35f weather. I use Water Wetter as well.
I mean this sounds exactly like what I am seeing too. I had a brand new ZX6 a few years back that ran at 154 in the winter, and the dealership told me that was just how they are. I was riding it in the winter in 28 degree weather and that's how it ran.

Isn't that odd?
-Mike
 

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if you're not running at temp in anything other than 50 below zero your thermostat isn't working, it's not the radiator its the thermostat not holding the coolant back, if idling your bike should always hit temp, fairing, insulated, yup... always

also remember your bike shouldn't kick idle down until the temp is at a certain point as well, and your thermostat should not let coolant through when closed, that's the whole point
 

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Discussion Starter · #12 ·
Do you think I actually got a bad thermostat? Even the 18yo thermostat I took off the bike only barely opened when it was in rolling boiling water. I didn't boil test the new thermostat, because it's a new thermostat. I can see the slight fluctuation in coolant temp when the thermostat first opens on every ride, so I know it's not sticking.

Today was upper 30's, and on the freeway I got up to 167 or so. As soon as I slowed down from about 75mph to 60 or so when I hit traffic, temps went right up to 175, then 180, then 200 or so in deep traffic, holding 180 even when I began moving again the rest of the way to the office.

Does it just take a lot longer to warm up on the freeway? I'm hesitant to throw in another thermostat... Maybe I will try a more accurate standalone temp sensor on the thermostat housing to see if the water coming out is actually 180-190F when it opens.

I've got mixed answers now here. Some folks said they have the same thing I do (or so it seems) and others saying it's gotta be way up there even around freezing temps to be working correctly.

Any more input? Think I got a new old-stock thermostat or something?

-Mike
 

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Hey folks,

Wanna see if my bike acts like yours.

Been riding my K4 750 around, and lately it's been pretty cool up here in the northwest. I am usually riding in mid 30's to mid 40's right now. About as cold as I would ride, and it's nice and dry for once. First winter with this bike.

Anyway, on the freeway my coolant seems to hold low 160's or so in these temps. When it was warmer, I was seeing more like 175-180F on the gauge on the freeway, but now I am seeing 160-165 on the freeway. Never drops below 160F once it has warmed up to at least that much.

In stop and go it gets up to the normal temps, fan comes on, all that jazz.
Bike rides great, and has a brand new thermostat. Very inclined to think it is working correctly. Running Engine Ice, and coolant system has no leaks and is bled right.

Is it normal for it to just run a bit cooler in the colder months? Is that what you guys have seen? Just takes quite a while to warm up when I get on the freeway in the morning. Should I make a partial radiator block for riding in the mid 30's, or does the engine just not care that much and I am just overthinking?

Thanks in advance.
-Mike
Personal record I've seen was 152F in wintertime on my K6
Was cruising through wet snow
In general, at minus-temps, the engine didn't get much warmer than that on the freeway
And K6's were known for being warmblooded
 

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Discussion Starter · #14 ·
Personal record I've seen was 152F in wintertime on my K6
Was cruising through wet snow
In general, at minus-temps, the engine didn't get much warmer than that on the freeway
And K6's were known for being warmblooded

That aligns with what I believe to be realistic as well. My suspicion is that GSX-R's are race bred machines with lights for street legality, and in general, motorbike races don't happen in cold temps, so they design the cooling system to be pretty powerful. And when you try to ride a supersport bike in cold weather, it's just going to have a hard time getting all the way up to the typical summer-running temps, regardless of the thermostat designed temp.

So I feel like that is just how the system works, but I wanted more experiences compared to mine. Your K6 sounds like how my late ZX-6 ran in the winter, on the freeway in the frigid cold it was 154F all the time. Ran perfect and got good gas mileage, so I'd assume it wasn't stuck in some super unusual fuel trim mode. I think that bike had a colder thermostat though.

-Mike
 

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FWIW the L7 1k I had would do the same. Wait for it to heat up and watch it drop to mid 160’s at speed. The L7 actually gives an ice warning on the dash like most modern vehicles these days, which I thought was interesting.
 

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Discussion Starter · #16 ·
That also sounds like what I am experiencing and have experienced. I guess on the older bikes it just doesn't read the temp below 68F or whatever it is instead of the ice warning. Would be nice to have the ice warning though lol.

Maybe I am just overthinking this too much. Thoughts?

Actually I thought too, I haven't ridden in the full on rain with my K4 yet. I wonder if it will run cold then as well, with the radiator fins full of water. Only one way to find out. Don't motogp and F1 cars use radiator blocks in the rain to get the engines up to full temp? I'd assume they also have high-temp thermostats, and then I would conclude that they also just have a hard time reaching temp with so much cooling going on...

-Mike
 

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Your over thinking this. Its cold, These bikes have everything exposed and are built to cram as much cooling air over everything to keep temps down. they wont get up to temp in the cold winter months. The thermostat bypass is enough to keep coolant flowing since thats its job. Its just too cold to out when moving.
 

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not sure I am over thinking anything, my bike stays at temp in freezing weather, all of em do? I mean it's not 70 below but it gets 25 or so, a few below zero at times, do you let it warm up fully before riding? I always allow my bikes to reach temp warm or cold..

so many cars reach running temps in well below zero in AK and the arctic so forth, they rely on their heaters working, some however will slap 210 thermostats in em, in the day you used to see semi tractors running zippable radiator covers, but no more, the engine compartments are more insulated and sealed off from the outside and they use hotter thermostats, again the thermostats job is to hold back coolant till it reaches a certain temps, if you think about it the engine on these bikes are sealed off in the front and not much in the rear is exposed so not a lot of fresh air is rushing over the engine itself..

you want these engines running at temp to perform optimally, again a hotter thermostat and allowing it to fully reach temp before riding may be in order, perhaps 5 - 10 minutes longer to allow the chassis to warm some up as well?
 

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My comment was towards the op. Sorry for the confusion.
 
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