YFZ450(Quad) Overheating bad?? Help appreciated!

[Khalid 171]

*Mods sorry if this is in the wrong section because it has to do with a quad but figured it was technical. Feel free if you need to move it to the dirt talk*

I know this has to do with a quad but figured some of you guys would know about it. My YFZ450 is overheating bad (fan and light on and the coolant will start boiling in resevior) and loses power. My light comes on within about 20 minutes of riding hard. It won't come on if I am just taking it easy and cruising around but as soon as I start getting on it for a while it gets hot. I am good on my jetting so I have ruled out that. I don't have any coolant in my oil and coolant looks good so I don't think it is the head gasket. I flushed out my radiator to make sure it wasn't clogged up or anything but it is still doing it. You guys have other ideas for me to check out and what to look at next? What type of coolant do you think I should be using? I just have a 50/50 mix, but what about something like Engine Ice? Is that an idea? I know it keeps it cooler but at the same time I don't want to just "mask" the problem. I don't want to have a bigger problem but just use that stuff as a temporary fix and actually cause some serious damage. Also what about the water pump? Is there a way to tell if it is actually working correctly? Anybody using high flow ones that made a difference? Sorry about all the questions but I want to get this figured out so I can start riding it again and not have fear of trashing the motor but again really try and figure it out and not just fix it temporarly and then run into things like warping. Any help, advice or tips would be really appreciated. Thanks in advance! :up:

[Spy007]

I never really had too much overheating with my 04 z400 when I had it, but you are runnin 50 more cc's... so i dunno how well they operate at WOT for an extended amount of time. 20 minutes just doesnt seem very long. Engine ice will help with the temps a bit and will definately raise the boiling point of your coolant. Also look at your fans to make sure they are kicking in on time, if at all.
As for blockage of any kind with the cooling system... since you are going to drain the coolant to add the ice, might as well check all the hoses to make sure that coolant is flowing properly. Other than that I dont really know why it would be running so hot if the bike is jetted properly.
Lastly... type of riding will play a bit of a factor. If you are doing non stop hill climbs, its gonna wear more on the engine and temp than if it were tearing through the woods or hittin the sand dunes where you have more air flow for the higher rev's.
I dunno... guess im at kind of a loss.

[R1chie]

If you have checked everything like flow, leaks and you have a fairly new quad I would replace the radiator cap. I had a friend who had a KTM that the cap was out of spec and allow the the pressure released too soon (not enough pressure) and it would overheat quickly under heavy use, once it started to boil the coolant would come out and cause a low fluid condition (do you notice the coolant is low after you noticed overheating?) which would make it worse. The spring on the radiator cap causes pressure in the system, this presure prevent boil over. If the cap spring is even slightly weak or allows the system presure to escape during riding, you will have boil overs. Another thing is the radiator cap seal is damaged or debris holding open the cap, also a burr on the radiator where the radiator cap seal meets the radiator itself. If you have another bike you could swap the caps or trade/borrow one from someone you go riding with. Good luck.

[Khalid 171]

Thanks guys. I have checked all the hoses and flushed out the entire system and replaced the coolant when it happened the first time. Everything seemed good but it still happened again the next time I went out with the new coolant. The fan kicks on normally (except really quick). Yes I am riding trails and hills at WOT but still, I would not think it would overheat that quickly. It is an 05 so about 2 1/2 years old but I do have a ton of mods on it if that makes a difference. I will get a new cap and I will probably just get a new waterpump and then use some of that Engine Ice or something similar and see how it does. I am just hoping it is not something else. Do you guys know of a way to check and make sure that everthing is working correctly like the waterpump or the flow of the coolant? Is there a way to watch the coolant in the radiator to see if it is flowing correctly?

[Spy007]

I dont know how with your quad.... especially since its all tucked into such a tight space. I wouldnt think it would overheat either... so im at a loss if nothing that Rich or I suggested works (which btw was an awesome catch by Ritch with the radiator cap, totally spaced it). If all else fails, you can always see if a local repair shop can give you some pointers.

[Khalid 171]

I went by a local dealer today and ended up talking with one of the service guys who races Pikes Peak and was having an overheating problem with his also. He actually said that he saw no difference with the Engine Ice and is switching back to the 50/50 mix especially since that Ice stuff is $20 a bottle :shocked: He told me just to check out the waterpump (internal stuff) but since I am not leaking coolant that the seals and what not should be good but if I do see anything on the impellar then just to replace the impellar along with the two seals. He also said I really need to switch to semi-synthetic oil or full synthetic and recommended I repalce the cap. He did all that stuff and said his has been a lot better but would still overheat deep into the race but not to the point of boiling. Hopefully this all works out. Boyesen makes a high flow waterpump but runs about $180 (OEM parts will cost about $60) so I want to make that a last resort thing if I can.

[R1chie]

If you changed the cap (which I think was the problem) changed the water to include a water wetter type material and put synthetic oil I think you will see a difference and not boil over. I did not read it if was mentioned but a lean jetting condition could also cause overheating but more likely to blow things up. Hope it works out for you.