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Discussion Starter #1 (Edited)
TL;DR bike gets really hot, really fast, fan kicks on, doesn't do anything, temp continues to rise, won't come down unless I begin riding. What is normal operating temp, when should I begin to worry about temp?

Hello everyone I am new to this site and just freshly upgraded from a grom to a beautiful (in my eyes) 2007 GSX-R750. Im new to the whole GSXR scene and I tried searching the forums but im either very dumb and cant read or I overlooked it. So bear with me.

Some details, i'm the third owner, I recently purchased the bike from a guy that had it for about 2 years and it was a leisure use bike for him. The guy before him is the first owner, and he owned it for about 11 years, he also used to track the bike on occasion. Anyways back to me, so when I purchased it, it had about 30,000 miles, as soon as I purchased it, I took it to a shop local to me and had them do a major service that included fluids, filters, valve adjustment (it didn't need it at 30k!) and a few miscellaneous things like tires, brakes, forks etc... So now we're starting with a fresh canvas, all new fluids. I went ahead and even replaced the radiator cap as those are known to lose pressure and cause the coolant to bubble.

Its about 80-100 degrees dry heat on average where I live, but gets down to 50-60 in the mornings and nights. So regardless of ambient temp, my bike gets really hot really fast. It basically climbs temp at a rate of 1 degree every two seconds. Even when the fan kicks on, it keeps getting hot, its like the fan doesnt do anything, it doesn't even slow down the rate at which the bike gains temp.

About the bike:
  • 30k miles
  • Well maintained, never been in an accident or dropped (as far as I know, and the shop said its very clean bike though)
  • Fully stock except for LED headlights and 2bros slip on exhaust (on 07 it deletes the cat), no tune/fuel management/power commander
  • No leaks whatsoever, and doesn't dump coolant from overflow tank when it gets hot.
  • Fan is operational, and comes on at 220 degrees.
  • No smoking at all
So far, I've taken it to a shop that has done the following:
  • Changed the coolant and bled the system, with 50% water / 50% anti freeze
  • Replaced radiator cap
  • Cleaned the radiator fins and removed all the bugs, road grime, and rocks. No bent fins, radiator looks to be in good condition
My observations:
  • At 50 mph+ on the freeway on 90 degree day, I'm averaging about 190 degrees. But on a 60 degree night, the bike is averaging about 175 degrees
  • Under 50 mph in the city its impossible to get it under 195 degrees regardless of ambient temp.
  • At stops, regardless of ambient temp, it gets super hot, even with the fan kicking on, I've seen it go up to 240 degrees, and I got scared and just took a detour to get some air flowing through the radiator to bring the temps down. If I approach a stop and i'm at 200 degrees, in 1 minute it'll be at 230 degrees.
  • As soon as I start riding again, the temps rapidly cool down at a faster rate than it heat up. So it will go down 2 degrees ever 1 second of riding.
  • When its hot 80 degrees+, the fan kicks on but doesn't do anything. When its below 50 degrees, it will go up to 225 and just stay at that temp until I start moving.
Im lost because I see some people say they never see above 200, some people say they don't see above 225, and some people say its normal to see 230. I tried searching for the normal operating range in the manual but I couldn't find anything. So can you guys tell me, is my bike normal and its just extremely hot where I live, or is something wrong?

I believe something is wrong because whats the purpose of having radiator fan if its not going to do anything, its supposed to work and make a difference regardless of ambient temp.

I am assuming the water pump, and thermostat are fully operational, otherwise the bike would overheat even when I'm riding, but it actually cools down very fast. The radiator cap is also a new oem cap, so im sure the system is holding pressure. The coolant flush was also done by a 5 star highly respected shop in my area, so I don't think they incorrectly bled the system. But you never know, the tech could've made a mistake, it happens.

So what do you guys have to say? Any help is greatly appreciated because I love the bike and want to ride it, but it sucks because with traffic and all the stops in my city, my temps easily sky rocket and I run the risk of overheating my bike. The shop I took it to says bike has no issues, but I wanna call BS because the temp should at least go down or hold its place around 220 when the fans come on. so could it...
  • Could it be a weak fan?
  • Could it be a faulty radiator?
  • Could it be a failing water pump/Thermostat?
  • Could it be due to air in the system?
  • Could it be due to the lack of a fuel management system?
I should also mention, the bike is completely stock with the exception of a 2bros slip on exhaust. No power commander, so could the bike be running lean at idle and thats whats allowing it to get so hot? The fan kicks on, so im thinking it could be three things.
  • Weak fan
  • Broken water pump blades
  • Air in the system.
  • Lean condition at idle (the bike backfires a ton though, so I think its actually running rich)
Please help me out guys, I'm a very paranoid person and I don't want to ride my bike knowing it has an issue, and knowing I can potentially mess up the engine. I did a ton of research but just cant seem to find an answer.
 

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I don't recall the exact temps but fan on at 221 and off at 105 sound familiar. 230 is when you start to worry.
 

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Discussion Starter #3
I don't recall the exact temps but fan on at 221 and off at 105 sound familiar. 230 is when you start to worry.
I have heard of that as well. People mentioning their fans come on and can do a pretty good job of cooling the bike down but not for me man. I cant even ride my bike, one long light and its already hovering around the danger zone. Im hoping someone has experienced similar issues and can guide me in the right direction.
 

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Do not assume the shop did their job correctly. KNOW they did. Check your coolant level, and bleed the system again according to the manual. If that doesn't get it, I would be looking at the water pump. I have heard the shafts can break on them?
 
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Do not assume the shop did their job correctly. KNOW they did. Check your coolant level, and bleed the system again according to the manual. If that doesn't get it, I would be looking at the water pump. I have heard the shafts can break on them?
That is true. I'll get some distilled water for now and top up and bleed the system as needed. After I confirm the bike is properly filled/bled, if that doesnt fix my issues, what is the next step in diagnosis? would it be the water pump/thermostat? or can there be such an issue like a weak fan or bad radiator. The reason I ask is because the fan, the radiator, and water pump are all around $200 each, and I would love to save a few bucks by doing the proper diagnosis sequence. Thank you.
 

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The ECM turns the fan on at 221F and usually my bikes will continue to climb a few more degrees before it pulls the temp down to where the fan goes off at 212F.

I remember a strange case where the fan wires were hooked up backwards so it was blowing the wrong way.

I know when my fan comes on, it is a very strong blast that I can feel back at the saddle.
 
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Discussion Starter #7
The ECM turns the fan on at 221F and usually my bikes will continue to climb a few more degrees before it pulls the temp down to where the fan goes off at 212F.

I remember a strange case where the fan wires were hooked up backwards so it was blowing the wrong way.

I know when my fan comes on, it is a very strong blast that I can feel back at the saddle.
Hey rv6john. I went and played around with my fan, when I put my hand behind the fan shroud I can feel air being pushed towards the back of the bike, is that the correct orientation? Also, when I manually spin the fan by hand, it will spin freely for 2/3 seconds before it comes to a halt, I don't feel any crazy resistance, its doesn't spin like butter, but doesn't feel like anything is holding it back.

Edit: I should also mention, I hear my fan turning on around 221, but the issue is it keeps climbing, and doesn't show any signs of slowing down to the 212 shutoff. Yesterday, I let it idle for 1 minutes and saw 238 and got scared and just took a different route so I can get some airflow through the radiator to cool it down. I don't think its normal for an air cooled bike to get hot like that when idling, if I couldn't lane split and take off at every light, its guaranteed to overheat just waiting for traffic to flow.
 

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Hey rv6john. I went and played around with my fan, when I put my hand behind the fan shroud I can feel air being pushed towards the back of the bike, is that the correct orientation? Also, when I manually spin the fan by hand, it will spin freely for 2/3 seconds before it comes to a halt, I don't feel any crazy resistance, its doesn't spin like butter, but doesn't feel like anything is holding it back.
That all sounds good. As I mentioned, I can feel mine with my hand back to where saddle is.
 

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This is normal with all bikes, my 750 that i recently traded would get hot fast like your describing, it was a 2019 with zero miles. Now my R1 gets even hotter! If you have the balls watch it till it gets to 230 and it shouldn't go above that, I don't have the required equipment to do that but when you are in trouble is when the red light turns on not matter what turn off the bike at that point. Most bikes have a auto shutdown if left idling for more than ten min they will cut the engine off. I feel your pain on this its almost like its going to burn up and your sitting at a light and that bitch won't go and its hotter than hell your sweating figuratively and physically cussing at Suzuki for being such dumbasses!
 

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And I forgot to mention the thermostat is usually of a 230°f temp that's why I said watch it to that it will if working correctly hit that then descend back to about 212°. RV6John thank you for reminding me in your post.
 

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Most bikes have a auto shutdown if left idling for more than ten min they will cut the engine off.
What bikes do you know that have this feature? None of my bikes do this, maybe some newer bikes?

In my opinion, this could be a very dangerous feature.
 
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Following. My son’s bike has the same symptoms


Sent from my iPhone using Tapatalk
Hey man I will update you as I go. Ive been swamped with school work, so once the weekend rolls around I may have some answers to guide you in the right path.
 

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Discussion Starter #14
This is normal with all bikes, my 750 that i recently traded would get hot fast like your describing, it was a 2019 with zero miles. Now my R1 gets even hotter! If you have the balls watch it till it gets to 230 and it shouldn't go above that, I don't have the required equipment to do that but when you are in trouble is when the red light turns on not matter what turn off the bike at that point. Most bikes have a auto shutdown if left idling for more than ten min they will cut the engine off. I feel your pain on this its almost like its going to burn up and your sitting at a light and that bitch won't go and its hotter than hell your sweating figuratively and physically cussing at Suzuki for being such dumbasses!
Hey man, the issue isn't that my bike gets hot fast, I know thats normal with no airflow through the radiator, but the issue is my bike will go to 260 degrees if I ever gave it the chance. Its so bad to the point where I cant even ride it because most stop lights in my area are red for a solid minute to 45 seconds. So thats enough time for my bike to go from 200 to 230 with no signs of stopping. My fan comes on, but doesnt do anything to bring the temps down. If im not mistaken I believe the thermostat opens up at 180 degrees, which mine is operational, I confirmed that. But yeah, it just keeps climbing.

I have a buddy with a 07 gsxr750, his bike idling in 100 degree weather will go up to 225 and come back down to 212, so I don't see why mine and his bike under the same conditions cant manage the heat the same. This weekend im going to properly bleed the system in case it hasn't been done, and then if that doesnt solve my issues im going to examine my water pump and replace the thermostat. Hopefully that solves my issues. But I will update everyone.
 

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If im not mistaken I believe the thermostat opens up at 180 degrees, which mine is operational, I confirmed that.

How did you confirm the thermostat was opening all the way at the correct temperature?

Also, does boil over at all when it gets hot?
 

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Ok so you are probably right except I would say your thermostat opens at or should open at 230 degrees and closes at maybe 180. When you see the temp drop rapidly that is only going to be the effect of cooler fluid from the heat exchanger rushing in the engine till it finally closes the thermostat again. No fan could cool something off that rapidly. I would like to say maybe if its not boiling over (and it will definitely boil at 240 mine boiled at 240 on my dirt romp the other day) be weary of the temperature sender could possibly be indicating an exaggerated temp.
 

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What bikes do you know that have this feature? None of my bikes do this, maybe some newer bikes?

In my opinion, this could be a very dangerous feature.

Well to be completely honest I only know of one for sure and that is the 2020 YZF R1 this is the only bike I have had personal experience with that will shut itself down. I did read it in the manual I have never tested it.
 

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Well to be completely honest I only know of one for sure and that is the 2020 YZF R1 this is the only bike I have had personal experience with that will shut itself down. I did read it in the manual I have never tested it.
I see that in the owners manual, their "auto stop" system after idling for 20 minutes.

My bad, I thought you meant that it would auto shut off due to a high temperature.
 

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I see that in the owners manual, their "auto stop" system after idling for 20 minutes.

My bad, I thought you meant that it would auto shut off due to a high temperature.
That is precisely what I was referring too. My bad I said 10 min and it is 20. I understand it as a shut off before a high temp situation but only when idling.

So I been racking my brain and it would seem to me you have a coolant flow problem, unfortunately not a fan problem. So the obvious steps would be KISS what ever is easier to change or costless go for first if you are worried about cost. If it was me since motorbiking is a hobby blossoming now into obsession I would change the pump and the thermostat, flush out my heat exchanger better yet take it off and have it pressure tested after the flush. I have never heard of it happening but if you bought it used there is a slim chance somebody added that radiator fix a leak bullshit. And for just for laughs change the sensor/sender. It could be that some dick altered the length of the wires on the sender which will indeed cause it to indicate a high or low temp when actually N.O. T. (normal operating temp).

Rest assured all the guys trying to help have a good understanding of bike mechanics so your in good hands (I am talking about every body else responding not really me) the money you save doing it yourself will allow you to get all of it hopefully! Keep us posted!
 

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Discussion Starter #20 (Edited)
How did you confirm the thermostat was opening all the way at the correct temperature?

Also, does boil over at all when it gets hot?
Well to be completely honest with, I didn't physically inspect it. But I did squeeze the coolant hoses at operating temp and they felt full and I could feel the fluid rushing through the hoses. And also since the temps rapidly cool down when I begin riding, which would indicate that the thermostat is open and letting fluid pass through the radiator, thats just my educated guess, so I believe those two would indicate an operational thermostat. But I will tear everything apart this weekend and update you guys.

Also no, from what I can tell the coolant is not boiling over, theres no overflow, and no steam or bubbling noises. But I will inspect everything this weekend, that could just be due to the water escaping the radiator and into the overflow tank.
 
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