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DRZ400e overheating on slow trails... 242F!!!

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I have a 2000 DRZ400e I picked up last fall, worked on it over the winter and rode for an extended period for the first time today.

It has a full big gun exhaust, K&N, MCCT, fresh syn. oil, full of coolant, jetting as specified by Eddie Sisneros, and I just installed radiator guards.

I rode a little bit of open field today, winding out 2nd and 3rd gears pretty good, mixed with short bursts of very slow 1st gear wooded trails. In the open field, my Vapor showed anywhere from 185-205 degrees. When I would go through the roughly 1/2 mile trail the temp would climb rapidly. I could hit 220 deg very easy if I went through the trail only once. If I turned around immediately and went back through it again, the temps would just keep climbing. I saw 242 deg once, before I realized I would need to run it through the open field to get it cooled back down. I spent the rest of the day riding pretty fast through the fields until the temps got back to about 190 before I would take the slow trail again, and then only once through it before doing a high speed run or two to cool her down again.

The bike seems to run really well at all temps and kept up fine with my friend's CRF450X all day. This being my first real outing on the bike, I was very cautious about the temps until I could get home and see what the TT collective had to say. What gives?

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What is you coolant overflow tank telling you?

Is it filling up?

Is it filling up with bubbling fluid?

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If it is not blowing coolant, it is not over heating. Put tape over the temp gage. With a 1.1 atm pressure cap and 50/50 antifreeze, it will boil about 265F. If it starts to boil, first thing to try is a higher pressure cap. KX500 is 1.6. Some KTMs are 1.8.

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before I rode yesterday, the coolant bottle had been empty, but the radiators were always full. The bottle was about half full when I noticed the high temps. I started it with the cap off to be sure there was some flow going on. Looks normal.

265F sounds really high for an operating temperature on ANY engine, but I'm just learning about these bikes. What really bothers me is that the ambient temp was in the high 40s, low 50s!!!

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I also wonder since I added the rad guards if that is blocking airflow much...especially since running at higher speeds brought the temp down so quickly. The guards don't look like they would affect airflow all that much.

???

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add a computer fan and ride it like you stole it. If it has a plate you need the fan in traffic.

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Only time my E has ever boiled is the first day I had it and let it sit at idle in the driveway too long. Yes I worry about idle in traffic but so far no problem. 100 F days in traffic I just shut the motor off and try to stay away from traffic.

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I rode again today in a different area, more open trails and a good bit quicker pace. Topped out at about 205F. I still don't feel warm and fuzzy about the fact I can't putt around on real tight stuff without temps getting over 240F, ESPECIALLY considering it's still pretty cool out...

I guess if these bikes are made to handle 240+F, I'll just have to get used to it...

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There is a reason they don't put temp gages with deg scales in cars anymore.

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Just by way of comparison, my tagged green E with Vapor does exactly the same thing on the mountain trails of Colorado, regardless of the ambient temps. I installed a 1"x4" computer on each radiator (in front, behind the Unibiker grill) with a h'bar mounted switch. I have my temp amber warning light set for 215F and usually flip the fans on when I notice the warning light. I've seen 252F when idling and not paying attention, and once it got to 276F when I was breaking in my Rekluse and the fan switch was broken. In the latter case, I did hear some boilover after shutting the engine off, but it was minor. I'm inclined to not worry about it if I don't notice my warning light until it gets into the 230s, but I do try to get the fans going at that time. And, I do think the temps run a little hotter after installing the Unibikers (at low speeds), regardless of what others say. It takes at least 10-12 mph before I get enough cooling to keep the temps down under 210F. I'm also inclined to agree with the others here in that if it isn't boiling over, all should be well (but I'm still flipping my fans on before it gets much above 230F).

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Thanks for the comparison and data points, Cuchara. I'll grab a couple fans. This eases my mind. Thanks for the replies, folks.

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I am in the same boat. I have a 2000 kicker, and when riding slow tight trails, mine gets really hot too, as indicated on my Vapor. I am feathering the clutch, since I am new to riding this kind of stuff, which I am sure, doesn't help.

I am probably gonna look more into installing these PC fans.

It would be great if someone did a nice pictorial writeup...hint hint hint. :banana:

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hey, +1 on the comp. fan. I mounted one on left side, in front of radiator, behind my devol guards. fit just right w/ a bit of dremel work. the whole set up cost less than 20 bucks and works great.

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I picked up the comp. fan (thermaltake 120x120x25mm), 18 ga. wire, switch, shrink wrap tubing, bullet connectors, and wire splices all from radio shack.

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I picked up the comp. fan (thermaltake 120x120x25mm), 18 ga. wire, switch, shrink wrap tubing, bullet connectors, and wire splices all from radio shack.

ok, thanks. I'll check out my local RS.

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I installed a 2X2 inch 12 V computer fan on each rad.guard ( $1.99 each) and no more overheating in the slow sections.

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