Holy Smokes the bike got hot

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Buell's most recent bikes had a fan on the rear cylinder to draw heat away, and it would run until the temps dropped even when the bike was off. It makes more sense because it was directly cooling the engine, though, and not the radiator.

 
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.
The problem with your post is that although you claim the charging "guess" is off by two orders of magnitude, it is you who has no idea what he is talking about.

The little equation you posted up is very fancy, and could be entirely correct, but for a CAR. I donno of you have realized this, but the FJR is not a car. It's charging system is powered by a stator, not an alternator, and it does not reach full charging capacity until about 5 thousand RPM.

Your equation's theory has been trumped by nearly 10 years of practical use. If a person commutes on their bike, and it is shorter than about 15 minutes, after about a week of start ups, and short rides, the FJR will start to show signs of a weak battery. After about 2 weeks, it may not start at all. A good long ride at higher steady RPMs will bring things back to normal.

So, instead of pulling the newb trick of spouting off how smart you are or how much you know about engines, understand that the people on this board have been riding, maintaining, working on, and discussing this bike for years. Some people here, who have proven themselves smart, instead of just claiming it, have probably forgotten more about this bike than you'll ever know.

So, sit back, drop the "I'm smarter than you" attitude and learn something. Lest your FJR disproves your mathematical theories and leaves you stranded somewhere.

 
^^^^ Exactly!!

I am one of those short commute guys, with a five mile ride to work. Then a couple of years ago my employer relocated and now it's barely two miles. If I don't find some place to go during the week besides work, I start seeing slow cranking in just a day or two.

OTOH, it's not that hard to say, "I think I'll take the long route home today!"

 
^^^^ Exactly!!

I am one of those short commute guys, with a five mile ride to work. Then a couple of years ago my employer relocated and now it's barely two miles. If I don't find some place to go during the week besides work, I start seeing slow cranking in just a day or two.

OTOH, it's not that hard to say, "I think I'll take the long route home today!"
...says the guy whose "long route home" takes him by this beach...

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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.
The problem with your post is that although you claim the charging "guess" is off by two orders of magnitude, it is you who has no idea what he is talking about.

The little equation you posted up is very fancy, and could be entirely correct, but for a CAR. I donno of you have realized this, but the FJR is not a car. It's charging system is powered by a stator, not an alternator, and it does not reach full charging capacity until about 5 thousand RPM.

Your equation's theory has been trumped by nearly 10 years of practical use. If a person commutes on their bike, and it is shorter than about 15 minutes, after about a week of start ups, and short rides, the FJR will start to show signs of a weak battery. After about 2 weeks, it may not start at all. A good long ride at higher steady RPMs will bring things back to normal.

So, instead of pulling the newb trick of spouting off how smart you are or how much you know about engines, understand that the people on this board have been riding, maintaining, working on, and discussing this bike for years. Some people here, who have proven themselves smart, instead of just claiming it, have probably forgotten more about this bike than you'll ever know.

So, sit back, drop the "I'm smarter than you" attitude and learn something. Lest your FJR disproves your mathematical theories and leaves you stranded somewhere.
Please explain to me why the charging system needs to reach maximum output to put 5 amps into the battery?

I purchased my FJR new in June 2006 and have never experienced slow cranking or a discharged battery. I do not own or use a battery tender. I have never seen the bike fail to maintain an adequate charge in the way you say is possible. My work commute is 15-20 minutes of suburban stoplight to stoplight riding. The reason I am doubtful my FJR is going to strand me is observation and daily use, not so much math. The math just confirms the observation.

I do have 30+ years of working on bikes and cars under my belt, just not interested in posting very much.

I was going to write a followup to Howie's response, but I seem to have lost my train of thought...

 
Hey RadioHowie, find out for Papa Chuy what their Mom's are doing tomorrow night.

Hell's Bell's, find out about their Grandmothers! I am an Irishman, I'm not real picky!

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I had no idea my simple post to make sure my bike wasnt overheating has turned into a physics class room debate...and all this talk about thermodynamics has me reminded of boring college classes...(Im a mechanical Engineer...and have some thermodynamics background)....however, I think I will restrain myself from entering this debate....I guess I just prefer to ride the thing and not think of it as trying to put the space shuttle on the moon...lmao

 
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.
but is that the total coolant or just that % that was in the motor? how is it averaged into the total coolant that wasn't in the motor (and therefore getting cooler than if the bike was running)? is the dissipation of heat from the stopped motor taken into consideration? what's the air speed velocity of an unladen swallow in flight? 2 European swallows carrying a coconut by the husk, suspended on a line between them?

 
Time to flush this one. POLITICS. There that should work. :p
But wait, noone has brought up Hitler yet - that's when you know a discussion on the internet is over! Though I suppose Monty Python will do. Let's all make like Sir Robin and bravely run away...

 
Your equation's theory has been trumped by nearly 10 years of practical use. If a person commutes on their bike, and it is shorter than about 15 minutes, after about a week of start ups, and short rides, the FJR will start to show signs of a weak battery. After about 2 weeks, it may not start at all. A good long ride at higher steady RPMs will bring things back to normal.
Horsecock! That is such bullshit. Stick to things you know sparky. Me thinks you are bringing a knife to a gunfight when it comes to any mechanical intellectual discussion with jcyuhn. Best just shut-up and stay home on this one. ;)

I used to do short commutes and errand running where I would do multiple starts in only a few miles. Never any issues. Your spewage above is nothing more than fjrforum internet rumor perpetuated by idiots who have no idea what they are talking about.

Have a nice day! :)

 
Your equation's theory has been trumped by nearly 10 years of practical use. If a person commutes on their bike, and it is shorter than about 15 minutes, after about a week of start ups, and short rides, the FJR will start to show signs of a weak battery. After about 2 weeks, it may not start at all. A good long ride at higher steady RPMs will bring things back to normal.
Horsecock! That is such bullshit. Stick to things you know sparky. Me thinks you are bringing a knife to a gunfight when it comes to any mechanical intellectual discussion with jcyuhn. Best just shut-up and stay home on this one. ;)

I used to do short commutes and errand running where I would do multiple starts in only a few miles.

Never any issues. Your spewage above is nothing more than fjrforum internet rumor perpetuated by idiots who have no idea what they are talking about.

Have a nice day! :)

Riiiiiight Skooter. You know, I initially stooped to your level and talked somead shit, but I'll leave it alone.

I mentioned the short commute time as an issue because when I was forced to commute on my bike I had to put it on a tender. BUT, do whatever the **** you want. Just like the ATGATT thread, I don't give a shit of your bike leaves you stranded. It doesn't affect me.

But now that you bring up being full of shit, please tell me what you would know about commuting to work every day?

 
Riiiiiight Skooter. You know, I initially stooped to your level and talked somead shit, but I'll leave it alone. AJ just tell him to go get his head fucked, again!

I mentioned the short commute time as an issue because when I was forced to commute on my bike I had to put it on a tender. BUT, do whatever the **** you want. Just like the ATGATT thread, I don't give a shit of your bike leaves you stranded. It doesn't affect me.

But now that you bring up being full of shit, please tell me what you would know about commuting to work every day? The SS Marbach takes a torpedo amidships and is listing to port!
Fixed.

 
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