Holy Smokes the bike got hot

[starsandstripes]

Your results are the same as mine. I commuted to work for several days when the weather was hovering around 99-103 here in Indiana, and the bike would get up to 7 bars at a stop light easily. It would usually be 5-6 bars when moving. I never saw 8 bars, though.

 

[jcyuhn]

All sounds normal based on my observations riding a gen II in Dallas heat. During the summer I will kill the engine when waiting at a stoplight that is going to last more than a minute or so. Then the engine doesn't heat up to 7 bars, which prevents me personally from heating up to 7 bars.

 

[Sparky.88]

Sounds like your Gen II is behaving normal. My Gen I gets up to 4 bars (just past middle of gauge) when stopped while riding in 100+ temp's. The fan kicks in at that point. But it goes back down once I'm moving again. Any yes, the engine does kick out quite a bit of heat.

 

[RadioHowie]

All sounds normal based on my observations riding a gen II in Dallas heat. During the summer I will kill the engine when waiting at a stoplight that is going to last more than a minute or so. Then the engine doesn't heat up to 7 bars, which prevents me personally from heating up to 7 bars.

Based on my experience, currently owning 2 water-cooled bikes, shutting off the bike for a minute or so isn't going to keep the temp low.

When you shut the bike off, the coolant is no longer circulating, so the coolant in the block and head is going to get hotter than the coolant in the radiator and hoses, as the coolant in the motor continues soak up heat from the motor. It's the First Law of Thermodynamics. Once you re-start the motor, now you have the (let's call it) superheated water from the motor enters the external part of the cooling system, i.e., the radiator. The fan sensor in the rad "sees" the heat spike and kicks off the fan to further cool the system.

I have personally seen this many times...pull in to the garage after a ride on a hot day and turn off the motor with the (Gen I) temp bars at 3. Leave the key switched off a minute or two, restart the motor and the temp gauge is at 4 bars and the fan kicks off.

The ONLY thing that could explain the temp at 3 bars when switched off, then 4 bars with fan at restart is what is known as "Heat Soak".

 

[HotRodZilla]

See what you guys did?? You went and made Howie say something smart. Now his head is gonna hurt for a week and he's gonna bitch and whine about it for twice as long........

 

[FJRay]

See what you guys did?? You went and made Howie say something smart. Now his head is gonna hurt for a week and he's gonna bitch and whine about it for twice as long........

If he shows up in September I'll buy his Reuben but he would probably bitch about that to. :lol:

 

[SkooterG]

The outside temp was ranging between 106-110...

The bike sure was pumping out some serious heat....

Even my passenger was extremely uncomfortable....

that was downright uncomfortable....

It's not exactly healthy to be out in heat like that, couldn't the ride have been postponed?

The bike was doing all it could to keep the engine temp down, so yes I bet it was pumping out some serious heat.

Uncomfortable probably doesn't even accurately describe what you both felt.

The A/C in my truck works great on days like that.

Wuss.

Healthy? Are you kidding me?

I ride in those temps EVERY day in the summertime here. And not only am I healthy, but I assure you I am quite *normal*. :jester:

 

[beemerdons]

See what you guys did?? You went and made Howie say something smart. Now his head is gonna hurt for a week and he's gonna bitch and whine about it for twice as long........

If he shows up in September I'll buy his Reuben but he would probably bitch about that to. :lol:

+1, Gunny; RadioHowie, also know as D.P. Gumby - My Brain Hurts!

https://www.youtube.com/watch?v=IIlKiRPSNGA

 

[wheatonFJR]

[i ride in those temps EVERY day in the summertime here. And not only am I healthy, but I assure you I am quite *normal*. :jester:

:lol: :lol: :lol: :lol: :lol:

yikes....

 

[SacramentoMike]

Based on my experience, currently owning 2 water-cooled bikes, shutting off the bike for a minute or so isn't going to keep the temp low.

When you shut the bike off, the coolant is no longer circulating, so the coolant in the block and head is going to get hotter than the coolant in the radiator and hoses, as the coolant in the motor continues soak up heat from the motor.

I agree with Howie and Scotty. I was a munitions guy in the AF--nuclear bombs, in fact, so they kept a close eye on us. We kept the bombs in these big secure double-locked igloos inside a double-fenced and closely guarded stronghold. When we needed one, we pulled it in on a trailer with a tractor or warehouse tug. One hot Monday we brought one in, and then parked the tractor outside, where it began erupting with smoke. LOTS of smoke. A couple guys got fire extinguishers and somebody else called the base fire department. You know, a little fire next to the building holding the NUCLEAR WEAPON!

Every fire truck, every Air Police vehicle, every officer from headquarters above the rank of second lieutenant on the whole base showed up. The fire was well out, of course. The first blast from our fire extinguishers blew the smouldering bird's nest out the other side of the tractor, where the little birdie had begun to build it on the nice warm engine block starting Friday afternoon. Naturally, the thing didn't start to smoke till the radiator stopped cooling the block after it was shut down. What a circus.

 

[RadioHowie]

See what you guys did?? You went and made Howie say something smart. Now his head is gonna hurt for a week and he's gonna bitch and whine about it for twice as long........

If he shows up in September I'll buy his Reuben but he would probably bitch about that to. :lol:

Irony is funny....just read this after coming back from lunch...where I had a Reuben!!

The only thing I could bitch about it...it was too small!

 

[jcyuhn]

All sounds normal based on my observations riding a gen II in Dallas heat. During the summer I will kill the engine when waiting at a stoplight that is going to last more than a minute or so. Then the engine doesn't heat up to 7 bars, which prevents me personally from heating up to 7 bars.

Based on my experience, currently owning 2 water-cooled bikes, shutting off the bike for a minute or so isn't going to keep the temp low.

When you shut the bike off, the coolant is no longer circulating, so the coolant in the block and head is going to get hotter than the coolant in the radiator and hoses, as the coolant in the motor continues soak up heat from the motor. It's the First Law of Thermodynamics. Once you re-start the motor, now you have the (let's call it) superheated water from the motor enters the external part of the cooling system, i.e., the radiator. The fan sensor in the rad "sees" the heat spike and kicks off the fan to further cool the system.

I have personally seen this many times...pull in to the garage after a ride on a hot day and turn off the motor with the (Gen I) temp bars at 3. Leave the key switched off a minute or two, restart the motor and the temp gauge is at 4 bars and the fan kicks off.

The ONLY thing that could explain the temp at 3 bars when switched off, then 4 bars with fan at restart is what is known as "Heat Soak".

Scotty removed for brevity...

You're overthinking this Howie. If you roll up to a long stoplight with the bike showing the typical 5 bars (gen II) and shut off the engine, the heatsoak will not trigger the radiator fans while sitting there. If you sit there for 2 minutes with the engine idling you might manage to reach 7/8 bars and trigger the radiator fans. I find it is primarily running of the fans while stopped that causes me personally to overheat. The fans create a nice cloud of hot air that feels like it envelopes the rider. In contrast, rolling down the road the hot air is mostly channeled our and around the rider. Much nicer. As to whether a burp of hot coolant triggers the fans while pulling away from the light - can't say I've ever noticed one way or the other.

As to physics - I am pretty sure that a non-running engine produces less heat than a running engine

 

[wfooshee]

During the summer I will kill the engine when waiting at a stoplight that is going to last more than a minute or so.

Besides the thermodynamics rebuttal to this process, I bet you'll be sorry you got into this habit when your battery starts showing signs of weakness, or your starter gets weird when it's hot, or your engine gives odd hot-start symptoms, or yada yada yada.

Additionally, it's been guesstimated that it takes about 20 minutes of riding to rebuild the charge lost from a single cold start. How that compares to a hot start depends on how well your bike starts when hot. The point is, several consecutive lights, you might one day find yourself with no crankie.

 

[jcyuhn]

During the summer I will kill the engine when waiting at a stoplight that is going to last more than a minute or so.

Besides the thermodynamics rebuttal to this process, I bet you'll be sorry you got into this habit when your battery starts showing signs of weakness, or your starter gets weird when it's hot, or your engine gives odd hot-start symptoms, or yada yada yada.

Additionally, it's been guesstimated that it takes about 20 minutes of riding to rebuild the charge lost from a single cold start. How that compares to a hot start depends on how well your bike starts when hot. The point is, several consecutive lights, you might one day find yourself with no crankie.

I didn't notice any thermodynamic rebuttal in any previous posts. I did see an arguement that a stopped engine puts off more heat than a running engine, and pretty much tuned out after that statement.

The factory battery only lasted 5.5 years in my bike, I don't see much of a problem there. I'll concede the starter sees more use and may well retire early. I can deal with that.

As for charging, you don't have to guess how long it takes to recharge. Lead acid batteries should be charged no faster than c/3 for maximum life, where c is the amp-hour rating. The FJR has a 14 amp-hour batter, so c/3=4.67. I'm gonna call it 5 because I like to keep things simple. The starter on the FJR typically draws 80 amps (look around the forum for confirmation). We'll assume 1 second of cranking for a hot start - frankly it's less. So we've drawn 80 amps for 1 second. The discharge rate is 16 times higher than the charge rate, so we need to charge 16 times longer. Lead-acid batteries are roughly 85% efficient on charge, so you need to put in more energy than you took out, so the charge time is longer still. Nonetheless, the battery is fully charged from the hot start within 30 seconds of riding. Your guess is off by 2 orders of magnitude.

 

[RadioHowie]

I didn't notice any thermodynamic rebuttal in any previous posts. I did see an arguement that a stopped engine puts off more heat than a running engine, and pretty much tuned out after that statement.

And that's a shame, because you misread or misunderstood most, if not all, of what I was saying.

I didn't say that a stopped engine puts out more heat than a running engine. I said the coolant that is currently IN THE MOTOR will get hotter beginning the moment you stop circulating the coolant. Shut the motor down, the water pump stops pumping and what coolant is currently in the coolant passages within the cylinder head and block stops moving. This (already) hot coolant is now "trapped" (so to speak) in passages, still exposed to the combustion heat produced just before you shut the motor off.

Therefore, when you re-start the motor, the coolant entering the radiator is hotter AFTER the restart than it would be had you left the motor running. Obviously, there is a "point-of-no-return" where constant idling will eventually lead to even hotter coolant, thereby triggering the fans, but that "point" is much longer than the minute you've shut the motor off.

On a similar topic, one of the disappointments I have with the FJR, or rather, Yamaha, is that when the motor IS hot enough to trigger the fans, when you shut the motor off and pull the key, the fan is stopped. My Kawasaki is exactly the opposite. Fan kicks on, shut the motor off, fan continues running until the coolant in the radiator drops below the sensor threshold.

Yamaha's method of killing power to the fan does the bike no good if you ask me. If the bike is hot enough to start the fan running, it should continue running until the temperature in the radiator reaches the "safe" point. BAD YAMAHA!!!

 

[SkooterG]

On a similar topic, one of the disappointments I have with the FJR, or rather, Yamaha, is that when the motor IS hot enough to trigger the fans, when you shut the motor off and pull the key, the fan is stopped. My Kawasaki is exactly the opposite. Fan kicks on, shut the motor off, fan continues running until the coolant in the radiator drops below the sensor threshold.

Yamaha's method of killing power to the fan does the bike no good if you ask me. If the bike is hot enough to start the fan running, it should continue running until the temperature in the radiator reaches the "safe" point. BAD YAMAHA!!!

No WAY! You are nuts. I don't want that current hogging fan running after shut-off. Might not be enough juice to re-start. Coolant temp is not measured at the radiator, but inside the engine. So what good is cooling the radiator after shut-off? It's not the hottest point, and is exposed to atmosphere for cooling. And you can cool the radiator all you want, but as you point out the engine coolant where temperature is measured will still be hot has hell keeping that fan running forever.

You're a screwy bastard!

 

[fjrchooser]

I'm pretty sure I toasted my chestnuts doing extended riding in those kind of temps on a Gen 1. Haven't and won't be trying to procreate since then so I'll never know but it was damned uncomfortable. I was boiling gasoline during a couple of tank refills.

Stay home or take something with A/C if you need to travel in those temps.

Word.

I can hit high C without trying and I used to be a baritone.

 

[beemerdons]

See what you guys did?? You went and made Howie say something smart. Now his head is gonna hurt for a week and he's gonna bitch and whine about it for twice as long........

If he shows up in September I'll buy his Reuben but he would probably bitch about that to. :lol:

Irony is funny....just read this after coming back from lunch...where I had a Reuben!!

The only thing I could bitch about it...it was too small!

This is very interesting and highly coincidental, that is the same constant complaint that Mrs. RadioHowie is always mentioning!

On a similar topic, one of the disappointments I have with the FJR, or rather, Yamaha, is that when the motor IS hot enough to trigger the fans, when you shut the motor off and pull the key, the fan is stopped. My Kawasaki is exactly the opposite. Fan kicks on, shut the motor off, fan continues running until the coolant in the radiator drops below the sensor threshold.

Yamaha's method of killing power to the fan does the bike no good if you ask me. If the bike is hot enough to start the fan running, it should continue running until the temperature in the radiator reaches the "safe" point. BAD YAMAHA!!!

No WAY! You are nuts. I don't want that current hogging fan running after shut-off. Might not be enough juice to re-start. Coolant temp is not measured at the radiator, but inside the engine. So what good is cooling the radiator after shut-off? It's not the hottest point, and is exposed to atmosphere for cooling. And you can cool the radiator all you want, but as you point out the engine coolant where temperature is measured will still be hot has hell keeping that fan running forever.

You're a screwy bastard!

Pot versus Kettle vs. Black.

Kick his ass, RadioHowie!

 

[RadioHowie]

On a similar topic, one of the disappointments I have with the FJR, or rather, Yamaha, is that when the motor IS hot enough to trigger the fans, when you shut the motor off and pull the key, the fan is stopped. My Kawasaki is exactly the opposite. Fan kicks on, shut the motor off, fan continues running until the coolant in the radiator drops below the sensor threshold.

Yamaha's method of killing power to the fan does the bike no good if you ask me. If the bike is hot enough to start the fan running, it should continue running until the temperature in the radiator reaches the "safe" point. BAD YAMAHA!!!

No WAY! You are nuts. I don't want that current hogging fan running after shut-off. Might not be enough juice to re-start. Coolant temp is not measured at the radiator, but inside the engine. So what good is cooling the radiator after shut-off? It's not the hottest point, and is exposed to atmosphere for cooling. And you can cool the radiator all you want, but as you point out the engine coolant where temperature is measured will still be hot has hell keeping that fan running forever.

You're a screwy bastard!

Sorry, but I don't agree. Yes, the fan is a current-whore, but the temp sensor which tells the ECU how hot the coolant is isn't "inside the engine"...it's in the coolant pipe right next to the thermostat, six inches or so away from the top of the radiator, so even with the motor off, on an already hot system, there is going to be significant convective motion between hot coolant in the radiator and HOT coolant in the motor. It's not like the fan is going to run for an hour, now is it???

On my Kaw, the temp sensor is plugged in to the top of the radiator, and has never had a problem with a post-shutdown fan killing the battery. The longest I've ever seen the fan run post-shutdown was 3, maybe 4 minutes.

But you are right in what you DIDN'T say....the FJR battery is a POS, and having an always-ready-to-run fan is probably a bad idea.

 

[jcyuhn]

I didn't notice any thermodynamic rebuttal in any previous posts. I did see an arguement that a stopped engine puts off more heat than a running engine, and pretty much tuned out after that statement.

And that's a shame, because you misread or misunderstood most, if not all, of what I was saying.

I didn't say that a stopped engine puts out more heat than a running engine. I said the coolant that is currently IN THE MOTOR will get hotter beginning the moment you stop circulating the coolant. Shut the motor down, the water pump stops pumping and what coolant is currently in the coolant passages within the cylinder head and block stops moving. This (already) hot coolant is now "trapped" (so to speak) in passages, still exposed to the combustion heat produced just before you shut the motor off.

Therefore, when you re-start the motor, the coolant entering the radiator is hotter AFTER the restart than it would be had you left the motor running. Obviously, there is a "point-of-no-return" where constant idling will eventually lead to even hotter coolant, thereby triggering the fans, but that "point" is much longer than the minute you've shut the motor off.

On a similar topic, one of the disappointments I have with the FJR, or rather, Yamaha, is that when the motor IS hot enough to trigger the fans, when you shut the motor off and pull the key, the fan is stopped. My Kawasaki is exactly the opposite. Fan kicks on, shut the motor off, fan continues running until the coolant in the radiator drops below the sensor threshold.

Yamaha's method of killing power to the fan does the bike no good if you ask me. If the bike is hot enough to start the fan running, it should continue running until the temperature in the radiator reaches the "safe" point. BAD YAMAHA!!!

Hey Howie, I did understand your point. I'm from Detroit, I'm a motor-head, I have engineering degrees. I see the coolant temp spike after shutdown all the time, so I know of what you speak. My point is simply that for my commute, in my climate, shutting off the engine at the longer traffic lights keeps *me* a lot cooler. The engine on average stays cooler too. It will typically show 5-6 bars, but never reach 7-8 where the fans come on. If the engine is left running at traffic lights (I go through about 6 major lights in the last ~4 miles home), the fans will come on at every light. The engine temp will perhaps drop one bar riding between lights, but it'll pop right back up at the next light, trigger the fans, and cook me again.

I agree with the followup posters that there is little point to cooling the radiator when the engine is not running to circulate the coolant. That said, I am OCD enough to leave the key on for a minute after pulling the bike into the garage, until the fans stop running. Can't hurt anything even if it is pointless, and in 6 years of ownership I haven't forgotten and killed the battery yet... oh jeez, I just jinxed myself, didn't I?