Bike getting hot at 120 mph

[sportbikey]

So I got this bike about a year ago and when I finally dug into it I saw that the coolant was like chocolate milk and I flushed it all out and replaced it. When are you tubed it there was a mention of a little drain plug with a washer and I used it but later on noticed that there's actually one on both sides of the engine. (Am i correct?) So I'm thinking either I have air trapped in my cooling system or my water pump is weak or I need to send my radiator out to get flushed out and serviced? Maybe thermostat issues? The weird thing to me is the bike idles and doesn't overheat the temperature does go up a little bit in stop and go traffic but it doesn't go all the way up to right before the red bar. On the interstate when I get open road and get up to100 - 120ish the temperature definitely jumps up.

Also I have the knock sensor code and the knock sensor wire looks pretty melted I was curious on how hard it was to change that harness because I ordered one of those. I ordered new washers for both of those drain plugs and then I ordered a new radiator cap.

If you think it's the water pump tell me how hard it is to do the water pump I think I read somewhere that it's advised to do the clutch while doing the water pump and I'm trying to understand the rationale behind that that tells me that it may be just out of my expertise lol.

I'm new to the ST 1300 and I'm just trying to get this bike ready for a road trip in Florida this summer and I don't want to have any issues lol. Thanks for the help guys!!

 

[pmatulew]

Why was the coolant like chocolate milk? That question needed to be answered and addresses before changing it. Thermostats are a known issue for the 13's. Usually manifest as low temperature issues. If the thermostat is working correctly the temperature seldom varies enough to notice.

 

[STumped]

So I'm thinking either I have air trapped in my cooling system or my water pump is weak or I need to send my radiator out to get flushed out and serviced? Maybe thermostat issues? The weird thing to me is the bike idles and doesn't overheat the temperature does go up a little bit in stop and go traffic but it doesn't go all the way up to right before the red bar. On the interstate when I get open road and get up to100 - 120ish the temperature definitely jumps up.

That is definitely NOT normal. Even when riding in 115° F, my temp gauge always shows three bars. You hit the nail on the head, you either have air in the system or a clog. Faulty water pump is rare (I have not read of it on this forum) and thermostat problems usually result in it being stuck open, not closed.

 

[PhotoDoctor]

Flush the coolant again, maybe several times and see what happens. I thought I had one of my st1100's flushed good but upon further inspection more stuff broke loose and was plugging the radiator and causing the temp gauge to shoot to the red at traffic lights. I'm on my 6th flush in two days and the problem seems fixed. I connected a garden hose to the lower radiator hose and pumped water out the radiator cap opening and washed out a lot of trash, then I ran some prestone flush through for about 50 miles - then kept flushing and riding till the water ran clear. Then a couple more flushes with distilled water and then replaced with coolant.

I would guess if your original flush was a mess you may need to flush several more times - good luck!

 

[dwalby]

Flush the coolant again, maybe several times and see what happens. I thought I had one of my st1100's flushed good but upon further inspection more stuff broke loose and was plugging the radiator and causing the temp gauge to shoot to the red at traffic lights. I'm on my 6th flush in two days and the problem seems fixed.

Didn't see any update on your other thread on the topic, so now the fan is coming on and cooling the bike back down as it should?

So it wasn't getting enough flow at idle because of the blockages, but when you revved it that helped push coolant through the radiator?

 

[Larry Fine]

Faulty water pump is rare (I have not read of it on this forum) . . .

I have. Trashed coolant can become corrosive enough to corrode pump blades.

 

[dwalby]

I have. Trashed coolant can become corrosive enough to corrode pump blades.

yep, happened to mine after neglecting the coolant for too many years. At least it made the decision easy whether or not to replace the water pump along with the timing belt.

 

[PhotoDoctor]

dwalby - i updated the other thread - all seems fine after multiple flushes and am hoping not have to get into the water pump for a long time as that bike only has 20K on it and 20 years.

I run the bike over the interstate bridges in Tampa then through some traffic for a 35 mile loop between flushes and the bike has not got hot again. The temp stays on the low side and never goes to the red.

I'm thinking the OP on this thread may be in the same boat with his one flush not being enough to get the job done.

 

[aniwack]

I'm just going to go out on a limb here as a former speed enforcer and ask the obvious: What compels you to discover the bike is running hot at 120 MPH??

 

[Larry Fine]

What compels you to discover the bike is running hot at 120 MPH??

 

[SMSW]

Forget getting hot, I wanna know how he's getting 120!

You need to read @CYYJ's post about his vacation in North Africa last winter. He was stuck there for a bit because of Covid. And, Michael rides his 1100, wfo between towns so 120's nothing.

 

[SMSW]

I'm just going to go out on a limb here as a former speed enforcer and ask the obvious: What compels you to discover the bike is running hot at 120 MPH??

Maybe its km/hr? Yeah, I know the OP lives in Florida. He must be flying under the radar...so to speak.

Seriously, there was a thread a couple of years ago titled, I think, "How fast have you gone on your bike" or something like that. I was surprised how many guys have had their ST's wide open. I know of one 50 mile stretch of interstate that often sees traffic moving at 90+, so it is not surprising that someone here would crank his throttle open a bit wider. I remember watching cars fly by doing more than 20 mph faster than I was.

 

[heffly]

Lol...you can get to 120 and back in less then a mile. Just saying.

 

[Kevcules]

I can get up to 100 mph for a few miles and never notice a temp increase, so I'm guessing your coolant circulation is still compromised and your thermostat is gunked up and not opening easily.
If your temp gauge goes beyond 3 bars at any time, you need to give your cooling system some attention.
Flush your system again and change the thermostat.

 

[st11ray]

I've seen 120mph across Hwy 2 in Montana. Never had any overheating problems though.

 

[Al st1100]

Knock sensor code will retard the timing some and cause the engine to run hotter. But I think a properly operating cooling system would control temps to the point it doesn't overheat. It sound like there is a couple of things going on. Run water from a garden hose thru the radiator about 5-10 minutes both ways. That should flush out the radiator. definitely change the T'stat. You should be able to splice in a pig tail for the Knock sensor rather than changing the harness

 

[ad.hom]

I'm just going to go out on a limb here as a former speed enforcer and ask the obvious: What compels you to discover the bike is running hot at 120 MPH??

Came to the thread for this. Was not disappointed.

Forget getting hot, I wanna know how he's getting 120!

You sir, are simply not trying hard enough. Back in the days before average speed cameras were everywhere, my average speed was somewhere north of 120. I have also left ExCel London at 17:30 on a Friday, and arrived at Starbucks in Soho at 17:39. I'll let you do the math on that one, but I did lock the front wheel up when I saw the speed camera markings and I looked at my dash to see a silly number.

Lol...you can get to 120 and back in less then a mile. Just saying.

Agreed. If we're sticking to a mile, lifting the front wheel is optional.

To the OP, your situation is certainly not normal. As someone else suggested, flush coolant again, does it look good, or do you have more crud in the system? Sounds like probably air in there somewhere too. Maybe, at a push, a pump issue, but I doubt it. Before major surgery I'd be hooking some wires up to the pump to see if it pushes fluid properly.

(and no, nothing in this post should be taken to be encouraging others to do whatever the hell I might be doing, I decided to mostly calm down the day that my rear tyre slipped sideways, mid bend, on a wet manhole cover, at "pace")

 

[caldercay]

120? That's nothing. I used to own a 'Busa (1999, year they were introduced)

EDIT: I originally had my sights set on a Blackbird, but we all know that a Hayabusa (Japanese peregrine falcon) is a bird of prey who stalks Blackbirds : )

 

[rwthomas1]

'Round here, between cities fast lane is 80+minimum, and frequently 90-100 for stretches. Easy to pop up to 110-120 on the open bits. Best ever was a 151mile run in 1:15min, including tolls, interchanges, etc. Wide open on the CBR1000 for a good while.

Cooling system sounds clogged to hell. Flush as suggested.

RT

 

[Sadlsor]

If you cannot get your hands on a new thermostat quickly, also consider examining your existing t-stat.
Several photos have shown up around here with paint chips or other crud fouling the spring in the thing, obviously impeding optimal operation. Sometimes paint flakes off the radiator pipes where the hoses attach.