Hot Hot Heat - Or How to Cool Your RC390.

ianblewitt

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Andy, My 390 has never experienced cooling problems. Prophylactically, I have fitted a SPAL fan, Engine Ice and a 1.6 bar radiator cap. During operation, the temperature bar sits consistently at 2 bars below hot, and moves very little. Others (unless their bike happens to have a cooling issue) typically report the same temp indication. I think 2 bars below hot is the 390's normal working temperature. So I think your bike is right on spec.

Mine too. It popped up to one bar last summer on the 105*+ day but otherwise generally sits at 2 bars.

Edit- I did have to add some distilled water when I first bought it, the first couple hundred miles I was worried I had gotten a "bad" RC, but before buying cooling stuff to "fix" it, I noticed it was looking pretty low. After filling up to the line with distilled, it hasn't given me any issues at all.
 
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cachidril01

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what about if I remove the thermostat?? would it be a solution to the heating problems? did anybody do it?
 
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Hotrocks85

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Thread revival...I did a search and could not find a definite answer. What about a pusher in front of the radiator and a puller in the rear. Mounting options aside, do you think that would help? Overkill? Would the pusher in front jam debris and small rocks into the vents?
 

ReidMcT

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Bad idea. It will reduce air flow when it isn't running, and won't help materially when it is.
 

Hotrocks85

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Bad idea. It will reduce air flow when it isn't running, and won't help materially when it is.
10-4. My bike has been overheating in traffic (after long harder rides), so I am trying to resolve the issue. Already have the SPAL fan on order, and will also drain and refill radiator with engine ice as next steps. Sounds like that will definitely help the issue, but time will tell. Thanks again for the response!
 

ReidMcT

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Instead of engine Ice, I'd recommend a super long-life coolant such as the pink coolant you can buy generically at NAPA auto parts. Or buy a name brand version such as Toyota long-life coolant. These O.A.T. coolants are not only cheaper than engine Ice, but they also have much more corrosion protection than Engine Ice or other typical propylene glycol coolants. Honda also has a good version that is blue. There's nothing special about Engine Ice, though it has a great name.
 

Hotrocks85

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Instead of engine Ice, I'd recommend a super long-life coolant such as the pink coolant you can buy generically at NAPA auto parts. Or buy a name brand version such as Toyota long-life coolant. These O.A.T. coolants are not only cheaper than engine Ice, but they also have much more corrosion protection than Engine Ice or other typical propylene glycol coolants. Honda also has a good version that is blue. There's nothing special about Engine Ice, though it has a great name.

Thanks for the recommendation. I have no experience with Engine Ice personally. The only reason I went that route was because it seemed the consensus was it was "the way to go". Now that I am comfortable with flushing and refilling the radiator, I wouldn't mind trying out engine ice, then possibly moving to the suggestions you made. Also, I already purchased a half gallon of the engine ice. :(
 

1JZSupra

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I use 100% engine ice in my 2016 duke. Freeway speeds I've data logged 184 degrees pretty much constantly. While at idle it goes up to 204 before the fan kicks on and knocks it down to 186. The engine ice helps to keep the heat down from what I have seen. I've been on 2+ hour rides in 90+ degree weather with no issues.
 

Hotrocks85

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I use 100% engine ice in my 2016 duke. Freeway speeds I've data logged 184 degrees pretty much constantly. While at idle it goes up to 204 before the fan kicks on and knocks it down to 186. The engine ice helps to keep the heat down from what I have seen. I've been on 2+ hour rides in 90+ degree weather with no issues.
That's good to know. Thank you for the info. I just finished the fan swap, flush, and refill. We'll see in the morning how it goes. It's been pretty hot lately, so I should know whether the SPAL and Engine Ice helped. (fingers crossed) Thanks again for your input, 1JZ!
 

Andyb

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That's good to know. Thank you for the info. I just finished the fan swap, flush, and refill. We'll see in the morning how it goes. It's been pretty hot lately, so I should know whether the SPAL and Engine Ice helped. (fingers crossed) Thanks again for your input, 1JZ!
Following along - I live in very hot climate (40-50 deg C common) Am familiar with Spall etc. for dirtbike. When you know would appreciate a heads-up. Thanks!
 

Hotrocks85

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Following along - I live in very hot climate (40-50 deg C common) Am familiar with Spall etc. for dirtbike. When you know would appreciate a heads-up. Thanks!
I just did the same ride yesterday, 70 miles one way, about an hour and 45 minutes In 95 degree heat. The bike held up well. I didnt have a thermometer to check actual temps, but my overheating issue did not occur. The temp gauge on the screen showed steady at two bars below the break (if that makes sense). I could hear the SPAL fan kick in, but noticeably quieter than the stock fan.
All in all, so far, I would say this upgrade worked in cooling down the bike more. Wasn't a dramatic increase in cooling, as this bike was always at a constant two bars below the break before, but this time it never once even wanted to go higher than that.
I would like to put more time into riding the bike to give a definite answer as to whether it helped, but it looks good for now. I will keep updating as I ride the bike more. Riding the bike to work today as it is about a 35 mile ride one way, so we'll see.
 

Andyb

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The temp gauge on the screen showed steady at two bars below the break (if that makes sense). I could hear the SPAL fan kick in, but noticeably quieter than the stock fan.
All in all, so far, I would say this upgrade worked in cooling down the bike more. Wasn't a dramatic increase in cooling, as this bike was always at a constant two bars below the break before, but this time it never once even wanted to go higher than that.
Hey HR85 - I use TrailTech TTO on my dirtbike. They have a temp gauge which plugs into the radiator fins. Super simple install for about $50. The stock temp gauge is crap according to Ari Henning (MCN) and he added one of these on his race bike. I think if it's a point of interest, this would help a lot. I know I'll get one. https://www.trailtech.net/digital-gauges/tto/surface-mounts/742-ef6 (make sure you use the bike selector to get the right one).
 

Hotrocks85

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Hey HR85 - I use TrailTech TTO on my dirtbike. They have a temp gauge which plugs into the radiator fins. Super simple install for about $50. The stock temp gauge is crap according to Ari Henning (MCN) and he added one of these on his race bike. I think if it's a point of interest, this would help a lot. I know I'll get one. https://www.trailtech.net/digital-gauges/tto/surface-mounts/742-ef6 (make sure you use the bike selector to get the right one).
That's a great suggestion, Andy. I will def. look into that. It would be nice to see an actual temp. rather than the stock gauge.
 

MagicEightBall

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I've read through several of the heating issues posts and consolidating some information here for those that may need an interim fix while their parts are on the way or waiting for time to tear everything apart.

It's summer, so temps are 90 or 100+. Had no issues in the 80s (always 2 bars from high, fan always brought it back down). My 2017 (new out of the crate in May) was "fine" as long as it didn't heat up from hard riding or stopping. If I stopped for gas or something, it would be 1 or 2 bars over and the fan alone wouldn't bring it back down when I started up again. Even after getting some airflow from easy riding, it would rarely go below 1 bar under. Went and got Engine Ice and was going to find something interim while I wait on new fan and a Dremel.

The culprit was the stupid rubber mat/shroud. No idea why it's there, but it's fairly easy to remove. Now, fan brings the temp down and moving will always bring it back to two bars under. A little more heat on my legs, but who cares?

A few tips:
- After removing the fairings, get scissors and clip around where it's zip tied to the frame, then remove the zip ties
- Carefully clip towards the spark plug hole
- Undo the radiator from the frame (no need to drain or anything) and lift the rubber mat off of two hooks behind the top of the radiator
- When changing the coolant, flush and flush and flush and flush by running the engine. I thought I had it, then others mentioned to run distilled water for a bit to flush. They aren't kidding. When you think it's running clear, it's not. Run distilled water in it for a little while, then flush again.
 
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