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DRZS overheating

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My brother has a 2001 DRZS. He removed the cooling fans a couple years back because my buddy said the E doesn't have it and you don't really need it anyway. Well yesterday in 50F degree weather at Hollister his overheat light came on. Granted we were on the Troll Trail which is really slow speed, but it was cool outside and the other bikes including one DRZE, a KTM 525, and a CRF450 were not overheating. There was enough coolant in there as he checked that and added WaterWetter just at lunch time.

The one thing that changed since we last rode was that he had the bike Dyno'd (which resulted in 32rwhp incidentally) and they leaned it out a bit. I guess the question in all this is that if they dynoed it to run to get the most HP will that cause it to overheat? I'm not sure what jets were put in but now we're sure going to find out.

Also the radiators don't show any major bends and he has the guards on them.

Any ideas?

Thanks for any input you can give....

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Could it be the pump? I don't know if you need to replace the impeller like in a boat or not. Maybe its not pumping the way it should. Or maybe I'm completely wrong. :)

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I'm sure Burned can tell you for sure but if a bike is running lean it will run at a higher temp. I overheated on a very cool morning last year and my friend raised the needle what that did I don't know but what i do know is i have not overheated again.

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if the bike was lean enough to cause hot running it would run noticeably bad.

probably just coincidence.

was he struggling?slipping the clutch?going slower than the others?

32 hp with a knobby i hope..............

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My brother has a 2001 DRZS. He removed the cooling fans a couple years back because my buddy said the E doesn't have it and you don't really need it anyway. Well yesterday in 50F degree weather at Hollister his overheat light came on. Granted we were on the Troll Trail which is really slow speed, but it was cool outside and the other bikes including one DRZE, a KTM 525, and a CRF450 were not overheating. There was enough coolant in there as he checked that and added WaterWetter just at lunch time.

The one thing that changed since we last rode was that he had the bike Dyno'd (which resulted in 32rwhp incidentally) and they leaned it out a bit. I guess the question in all this is that if they dynoed it to run to get the most HP will that cause it to overheat? I'm not sure what jets were put in but now we're sure going to find out.

Also the radiators don't show any major bends and he has the guards on them.

Any ideas?

Thanks for any input you can give....

There's your culprit right there.

The DRZ is already lean from the factory. to lean it out any more will cause it to overheat and could do dammage to the engine. :)

Edit: Yeah also what Burned said :)

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???, are the radiators clean?, did he have any preignition,(pinging)?, did the bike loose any fluids?, are the valves in spec?,did he notice a loss of performance?, Did you check for vacum leaks?. Many questions, could just be a bad coolant temp sensor?? :)

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Did it loose coolant? If not, it probably did not overheat. All the other bikes you rode with have no temp light. If they do not loose coolant, they did not overheat. Use the same logic with the DRZ "S" when it has no fan. If you are loosing coolant, then you need to correct the problem.

32 hp is not all that great and as burned said, you can't get an accurate dyno run with a knobby. You should try the jetting recommended here on TT. It is proven over and over.

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There is one other little difference between the cooling systems of the E and the S that most people don't realize and that is that the E doesn't have a thermostat. I'm not sure how much flow it cuts down but it has to impede it at least a little bit.

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He said the bike was running better than it ever had before it overheated. It did have the knobby on for the dyno run too. And it definitely did overheat because it started running worse and worse until it cooled off and he added the coolant and water wetter. Re rode until it heated up again then he shut it off and it wouldn't start again even going downhill and trying to bump start at 25mph. Luckily we were at the top of the hill and had a 1000' downhill or we would have been screwed. Didn't even have to use the buddy tow. It sounds like since it was running so good that the jetting has less to do with it than the cooling system so we'll start there. Hopefully it didn't heat up too much to screw things up.

Thanks for your input!

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DRZ-S on a troll trail? Why not just walk instead, it'd be faster. :)

BTW, I'd check the jetting closely too...they can run unusually strong when a little too lean - that's kind of a hint something's up. I've learned to run my off-road bikes a bit on the rich side.

I practically live on the troll trails, and plan to install an optional fan on my CRF250X - because it overheats in many spots where forward motion sometimes happens to be near zero, like when it's laying on top of me.

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