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DRZ400E Overheat Symptom Questions

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Hi all,

A bunch of us hit Elkins Flat this weekend, and between the Snow, the 4+ foot deep mud puddles, the clay pits, downed trees, mud slides and raging river it was one of the most challenging weekends ever. Seeing as I ride a YZ250F (I'm asking this stuff for a clueless friend) I thought I might ask the Suzuki experts here:

The bike: 2001 DRZ400E -- bone stock

The issue: Riding way too slow and too much idle caused the bike to overheat several times.

The questions:

1. When the bike overheated it would not start again. You'd press the E-start button and nothing. Let the bike sit 20 minutes and it would work again with no problems. Is this normal??

2. If it is normal for the bike not to start when boiled over like that, is there a way to bypass this? There were a couple of times that it actually got kind of dangerous not to be able to start the bike. Is there a thermastat or something I can remove? What about the kick-start kit, will this allow the bike to still start with the kick start rather than the E-start?

3. I've read a lot of the posts here and find that the stock DRZ runs very lean at stock, but we were at 3000 feet, so I would have assumed we'd be OK because it should have been running rich. How far should I richen the bike to make it in a safe range for ~sea level?

4. Is there a way on the 2001 DRZ400E to put in electric fans? This might help when we are going so slow.

5. Is there an overflow bottle kit for that bike? It didn't seem to have one stock so by the end of the day he had essentially run out of coolant.

I talked him in to immediate replacement of the coolant with Engine Ice and going to a high pressure cap. That will be the first step in "helping". Also, there is no overflow bottle as I said earlier so I might fashion something up for him if there isn't a kit.

Sorry for so many questions by my own YZ250F went all day idling even more than the DRZ and it didn't boil over until the very end of the ride and as soon I finally made it to the road I was able to get it cool again. I have never had these problems. The DRZ400E seemed like an absolute tank (slow but very steady) and other than this problem it performed flawlessly all day during a 9 hour ride.

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Have you considered using the Evans NPG+ coolant. I'm planning on using it in my S converted to SM just for it's superior cooling and the fact that it's a low/no pressure system not because I anticipate any cooling problems. It sounds like it would help alleviate the problem in the circumstances described.

http://www.evanscooling.com/html/npgPls.htm

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1. When the bike overheated it would not start again. You'd press the E-start button and nothing. Let the bike sit 20 minutes and it would work again with no problems. Is this normal?----No.

2. If it is normal for the bike not to start when boiled over like that, is there a way to bypass this?-----See above.

There were a couple of times that it actually got kind of dangerous not to be able to start the bike. Is there a thermostat or something I can remove?-----No. No thermostat in the E bike.

What about the kick-start kit, will this allow the bike to still start with the kick start rather than the E-start?----Possibly, but I would rather find the E start problem.

3. I've read a lot of the posts here and find that the stock DRZ runs very lean at stock, but we were at 3000 feet, so I would have assumed we'd be OK because it should have been running rich. How far should I richen the bike to make it in a safe range for ~sea level?-----Plenty of posts on jetting. My bike is close to stock jetting and it does not overheat unless there is a good reason - no air movement and a lot of revs, just like your experience. Same with my KDX200. My 200 EXC has larger rads and is much more tolerant about overheating

4. Is there a way on the 2001 DRZ400E to put in electric fans? This might help when we are going so slow.----Yes, 12 vdc computer fans.

5. Is there an overflow bottle kit for that bike? It didn't seem to have one stock so by the end of the day he had essentially run out of coolant.-----All models of DRZ come stock with one. Right above the chain on the left side.

The DRZ400E seemed like an absolute tank (slow but very steady) and other than this problem it performed flawlessly all day during a 9 hour ride.-----Sounds about right compared to a 250.

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Thermostat that is stuck closed, is one thing that can cause this overheat... the other, most commonly overlooked is the radiator cap.

You say that the bike is a 2001 model, so it could be that the seal on the radiator cap has age hardened and has fine cracks and lost its sealing properties.

A poor sealing cap will not allow the radiator to be pressurised which results in the coolant boiling off at a lower temperature.

The higher the pressure the higher the boiling point.

Try replacing the radiator cap with a new one if this has not been done yet.

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The E has no thermostat, so it cannot be that. Coolant, as it ages, boils over sooner. would not hurt do do a fush and refill. Could be the cap has lost its' personality, so a new cap is not a bad idea. If slow riding is going to be the norm, you may want to consider adding a fan.

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Quote on a PC fan, 80x 80mm.

Since the installation many months ago only 1 overheat with boiling water, yesterday in a very nasty and steep trail, lifelong minutes high revving the motor to try to escape and come back to civilization.

No problems at all with many many many deeeeep water crossings :bonk:

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The DRZ400E seemed like an absolute tank (slow but very steady) and other than this problem it performed flawlessly all day during a 9 hour ride

The price we pay for reliability and durability. The overheating problem your buddy is experiencing is most likely something simple. I have had my E in a few creek beds where the YZF's and CRF's that accompanied us were spewing coolant. I didn't loose a drop, possibly thanks to the overflow.

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Thanks guys!

This gives me some good stuff to look at. Does anyone have a link to a schematic of the like for wiring up the 80x80mm PC fans? I have plenty of those hanging around the house (Hey, im root user). Would be great to see it done so I get it right.

I will be headed out to buy a high pressure radiator cap and I'm going to go ahead and switch him to Engine Ice or something like it.

I'll have to look at the overflow. Maybe it's unhooked or leaking. That thing was steaming like no tomorrow.

Overall I am not impressed with the power from the Suzuki but I will have to say it made the trip with a newbie rider on it, so as a rule of thumb, I would say Suzuki is a good weekender trail-bike. I really didn't expect it to perform so well after all the horror stories I've heard but my buddy couldnt be happier. :bonk:

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I don't have a schematic of the wiring for the connection of a PC fan, but in my case it was dead simple: connected in series to the ignition switch, always on when the key is in the "on" position. :naughty:

The current draw is just a few milliamperes, so in my opinion it's not an issue to have the fan always on. 😛

You just have to be sure and position the fan in the correct way, to push air towards the radiator, and not the other way round.

:bonk:

Apart for that, a very easy installation, and I must say I'm the sort of guy mechanical/electrical challenged !!!

:D:bonk:

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orange wires are hot when the key is on. black with white tracer is the ground. couldput a temp sensor in if you want to switch fan on and off. oem fan on a s/sm is behind the radiator, left side, pulls air through.

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