Hey all, I may have a cooling problem on my 07 GSXR 750 and wanted some input. History: on the street it always ran a very consistent 180 on the the thermostat and when I came to a stop never really fluctuated much unless idling for longer than a couple minutes. Setup: stock pipe, Power commander, water wetter. On track experience: thermo shows 190-195 running hard mid-pack advanced. Problem is that when I pull into the pits, shut down, temp runs quickly to 220, fan kicks on, hovers @ 225-230, then starts coming down. This was at Putnam on a 75-80 degree day with 20mph winds hitting her on the nose in the pits i.e. pretty much the coolest and best pit cooling conditions she'll see this year. 1, is this a problem or just normal for hard track running? 2, do I need to burp the cooling system, did I get air in somewhere when I switched to water wetter? (overflow tank has coolant showing and radiator appears full so NOT low on coolant) 3, do I just need to make a better attempt at a true cool off lap and cool her down before pitting? I did this at Putnam and ran out to the gate and back at low RPM and the fan hardly came on, if at all, once in the pits. Seemed to solve the problem if it even is one? Just worried I'm gonna cook the engine as we head into the real heat of summer and wanted to see what the board thinks Thanks all, Grant
I would check to be sure there is no air in the system. There is a bleeder screw on the water pump housing, as well as the back of the thermostat IIRC. It sounds like it was working properly on the street, so the issue happened when you swapped to water and water wetter.
I also run a 2007 GSXR 750. She runs 180 on the nose on the track and warms up as I slow to enter the pits. I am a bit baffled if there is no air in your system as to why your bike heats up so much. My bike actually ran cooler until I had a supersport build done last year. I would be interested in what temp others see who ride a 2007 GSXR 750. Tim O'Toole
Take your fans off. The radiator will move a lot more air through them. Most bikes see a 10-15 deg drop. Your motor is safe well above 235 deg. You have nothing to worry about.
My bike a 06 GSXR750 does the same thing dont worry about it. My temp is fine but as I come in the pits she starts to climb to about 220 then fans come on and it goes down. Has allways done this since day one in the warmer temps. I think u r running cooler on the street because u r riding at a much more mellow pace. Ive just put in eng ice last year with no change in temp. I was told to take off fans also but that scares me as im a mechanic and know that its important to have the air flo when putting around. I wish I could shut the bike off and the fans would run for like 2 more mins and then shut down like all cars do.
The fans still running would do very little for engine temps. The water is not circulating any more, so all you are doing is cooling the water in the radiator some. The water in the block is still going to rise in temp once you shut the motor off.
True but it would help cool the motor off on start up quicker and some air blowing over the motor is better then none at all even if its hot air. I see the point though. Hey how about an electric water pump then we can patent it and make millions.
Is 220 an accurate reading if the engine is not running and the pump is not pumping? At this point, the water is stagnent at the location of the sensor and the reading is at that location. I expect the water temp to increase when you come off the track due to the reduced air flow across the radiator. If the higher temp is a concern, maybe it makes sense to let the engine idle, let the pump to pump, let the fan to suck, etc. until the temp drops enough that the stat turns the fan off. BTW, I think this is typical and shouldn't be an issue. I have to believe the components are specified at a much higher temp than you are seeing. The design should have some overhead.
Cooling the water in the radiator will also cool the engine because the water will continue to flow by convection. This is from the change in density of the coolant. The Ford Flat Head V-8s have no water pumps at all; pumping is by convection only. The key here is the amount of HP generated by the engine; just like an air cooled engine, you can only build the air cooled engine to a certain power level, any more and water cooling becomes necessary. The more power that is made, the more heat, the more heat then naturally the more cooling that is required. Removing the fans helps cooling because the fans on the motorcycle are place before the radiator and block fresh cool air from reaching part of the radiator. Most cars have electric fans after the radiator for this reason and our motorcycles just don’t have space for this. If all you did was idle around in city traffic on 95 °F sunny summer days, well then, yes the fans would most decidedly be needed. My R1 will leave the fans running with the key off if the thermostat calls for the fan to run. If you are really that concerned buy the SuperBike kit radiator. But like said in a previous post, an engine is fine up to 240 °F. Electric driven water pumps exist and is a common automotive modification for the really high horsepower engines. I believe the top fuel drag bikes use them too. Engine drive (gear) is a more dependable way to do it and it takes the same amount of energy to do this. One advantage with electric is it will always move the same amount of water regardless of rpm.
Thats why I dont want to remove my fans because they are behind my radiator on my GSXR750 so I dont see a restriction. Meizure makes electric pump for cars and thats what I used drag racing. Was nice to come to the pits and turn the fan and pump on. It cooled off in no time.
Think about that logic for a second. For easy visualizations sake lets pretend we are talking about taping up a radiator opposed to the infinite number of variables when using fans as an example. You say that fans behind the radiator don’t reduce flow. That is 100% wrong. Let’s say you have a radiator and you tape up half of the front surface. Obviously there will be half the air flowing through (key word) the radiator and the temp will increase. Now, remove the tape from the front of the rad and put the same amount of tape on the backside of the rad. How much air do you have “flowing†through the radiator now? The answer is……… the same. There is also the widespread misconception that the goal is to get your motor to run/be as cool as possible. There is a thing called thermal efficiency and where it has more facets than I understand or even really care too, you will find in most high performance motors coolant temps are run very, very high. A lot of the Superbikes run pressurized cooling systems (up to 32psi on the Ducati’s) so the boiling point of the water/coolant is raised to a point that they can run the coolant temps in the 220-230deg range where the motor is more thermally efficient. NASCAR motors run some silly high coolant temps. And it’s hard to argue with a 800hp, 8500rpm, 355cu in pushrod motor that lasts 500 miles wide open being set up wrong. A quick example was my 999R which I had WSB radiators and oil cooler on. While on the dyno I found that the motor made 8 more hp if the coolant temp was at 210 or higher opposed to 180. After that dyno work I made it a habit to tape the radiator up on cool days to raise coolant temps because the radiators would have it running as low as 150 deg if I didn’t (no thermostat with the Corse cooling system). Once while on the dyno and doing some long hard 100% pulls I accidentally missed the coolant temp getting up to 245 deg. While cooling the bike down I goofed around with the runs to see what we had and the runs I made at or just under 245 deg weren’t down 1hp on the runs at 210 deg.
I agree with ya but the tape will allow no air movement were the fans are still letting the air out but I get your point. Pres in the cooling system def raises your boiling points. If ya want to get really get confused we used Evans Coolant in our car race 800hp motors again with higher temps but they were more efficiant then they were with water. We could run temps above boiling points of water without issues because heat makes power. Not hot air coming into the motor but thermal effic. I did alot of drag racing before my track day addiction started. After the 1/4 mile pass if we didnt shut the car off and just took it easy back to the pits without a fan it would overheat but I know thats cars. As we know it gets pretty technical.
I burped the system at the pump as suggested and did seem to get some air out. My wife then ran the bike at Gateway and no temp issues but her "Thermal Demands" aren't quite as high as mine shall we say. I think it helped and am not sure it was even a problem but I feel better about it. I doubt I hurt anything as the water temps while WFO on the track were fine ~195-200. So more than enough air and water flow on the track as far as I can tell. It'll be interesting to see next time I ride it hard if the temps spike as much entering the pits?? Was water flow compromised by air in the pump chamber? Maybe? I can't believe the air wasn't purged after a double at Barber and a double at Putnam but it seemed some came out when I purged the water pump! Bottom line, even for simple jobs, get the manual. I figured changing the coolant was so simple that it wasn't needed. The manuals are 7 bucks downloaded from ebay these days (which I did after starting this thread) so no excuses. Even simple jobs may have some nuance or steps that aren't apparent. See ya'll at the track
This thread is about a bike that has an obvious cooling issue (must be air in system) and some of you guys recommend removing the fan right out of the gate? Seriously? No troubleshooting at all? The fan has no measureable impact on the airflow through the radiator. Why? For one, it spins. Also, there is only a sharp edge of the blade anywhere near the face of the radiator. Sure, there is a shroud. But this is a very very small percentage of the radiator. Also, the bike is designed to work with the cooling package that it has. Not to mention that everyone elses bike works fine with the fan and thus there is something on this bike that needs fixin'. And.... the complaint is that this bike is too hot SITTING STILL as well. What good would removing anything from the radiator do when there is no airflow to restrict? It just takes one time... just once for you forget that you don't have a fan while the bike is sitting still, idling at a stop light, in the pit, when you went to the port-a-potty while you bike was warming up in the paddock and you got distracted on the way back by some hot dogs at concession, etc, and the engine is toast. Blown head gasket, cracked head, water in the oil, damaged bearings. This is like going to the doctor, complaining about a high fever, and having him tell you that you need to start taking cold baths in the morning instead of warm showers.