Kawasaki VN750 Forum banner

What? Another fan thread?

6K views 32 replies 5 participants last post by  roadpouring 
#1 ·
Hey all!

I have finally after several months working with the previous owner acquired my machine. Rode her 35+ some-odd miles home over the mountains from his shop. Much work had to be done before that ride was possible, much rebuilt in the shop, but that's another story.

On the way back the coolant reservoir overflowed after much riding and finally meeting city traffic. With only about 8 miles of inner-city rush hour traffic to go i endeavored on until finally she died and battery wouldn't kick her over. Pulled over and we both cooled off for about 20 minutes, started her back up, head home, and took a look at her this morning. Battery problem was obvious, the shop has a "genius" mechanic. One of the cells was bone dry, another was about half way up the wall, the others were fine. Replaced the battery with an ETX15L AGM. With that problem solved, i refilled the coolant, restarted, let her get warm, shut her down and she sucked up a full reservoir of coolant. Refilled, that's all fine now too.

Talking to my friend, the shop owner on the phone, he was asking about the fan. And sure enough, as far as i know the fan hasn't yet turned. So, i have read all of the various troubleshooting articles about fans in this section of the forums, and it will be tomorrow before there is enough light to ground the fan-switch, etc. I combed through the maintenance manual, etc. as well and i still have one question i simply cannot find the answer...

What is the temperature ( on gauge or otherwise ) where the fan should turn itself on? Should it just turn on after the bike is more or less idled warm? Does it turn on only when it's sensing extreme heat? I am tempted to just go ahead and put in a ground toggle to bypass the switch as several have suggested ( as well as the shop owner ) but since this is my first VN750, i still haven't a clue when i would turn the switch on myself. If it runs constantly on a switch while the engine is turning, is that going to pull down the electrical system... lose battery life? Is the fan loud enough to hear while out in typical traffic? On the flip side of the coin is a very wise anecdote: if it ain't broke fix something else, like my ears. :doh:

Other than that, she simply howls... she has a lot of minor problems, but most of them are cosmetic or broken items and she needs TLC. So this fan question is basically the only thing standing between riding on "reliable" and "worry". Know what i mean? :)
 
See less See more
#2 ·
on my bike, the fan turns on at just about 1/2 way on gauge.. maybe a little higher.. it does not run full time (when ign is on). I cant really hear my fan when sitting still and it turns on, but I can sometimes feel an increase in warm air around the legs (I live in the south, and usually have shorts on..)

the ground to bypass the temp switch in the bottom left of the radiator is a testing method in my opinion.. I think you would be taxing the charging system if you left it running all the time. if you ground the wire and the fan runs, then everything else in the circuit is working properly and you just need the temp switch.
 
#3 ·
Same here, I don't always hear the fan, but can feel the hot air when it kicks on about midpoint of the gauge. Sometimes at a stop I'll just lean over and look at the blades.

When my fan quit, the spade terminals in the Junction Box plug were loose. Just had to pull them out of the plug, then pinch them with pliers to fit tight. I grounded the fan switch wire then wiggled the wires at the JB plug to find the loose spade. It's one of the blue wires, I think.
 
#4 ·
thanks and update

Thank you both for the info. Pulled the wire/socket off the fan switch, used some #2 high grade toilet tissue to sop up the oil glut around the switch's tab and inside the socket using a J.C. Penny stock number #NSN 7510-00-958-0743 paper clip which fortunately for me, somebody had left nearby in the weeds of the parking lot. They must have been psychic, i guess.

With the wire disconnected from the switch, i shoved a flat end screw driver into the socket and used the neck of the same to ground the JB relay's coil circuit to a nut on the frame. The fan started to whir which made me smile.

So now i am thinking about a mod. I know eventually someday that switch might just fail ( presuming it's working now ) and leave the fan running all night. And i like the idea of a switch on the handle bars to avoid that situation. I also like the idea that the engineers designed it to be automatic so i am thinking about a mod that does the best of both worlds. An LED could be run in series with the coil side of the JB relay to light up whenever the fan is supposed to be on. A switch could be run in series as well and simply turned on when running, off when parked, and instead of being an override, being an enable/disable switch for the control side of that system.

I took her for a short ride today but the temperature stayed below the halfway mark so really don't know yet if the temperature switch is actually working. There is really no reason to doubt that switch though since it was out of circuit due to all the oil in that connector on the way home the other day. There is equally no reason to believe that i have a good connection there either yet. So for now, i am happy at least a "culprit" was found and can monitor the situation with an informed perspective.

Thanks again and if you have any ideas about that mod, let me know. I'm going to hunt around for LED toggles that can get that mod job done.

:rockon:
 
#7 ·
Exactly. So the idea is that while riding, a quick check of temp-gauge and the LED should tell the story. If the gauge is leaning to the right and the LED is on, everything is fine ( at least on the sense/control side ). It won't ever really mean the fan is actually turning, just take the fun out of troubleshooting with a screwdriver while on the highway. :nerd:
 
#8 ·
I get the drift of that as well as what Spock was saying.. i suppose if it's really worth doing a "full" mod, what would do the trick is two switches and an LED, and instead of the LED watching the control side, since it's on a relay anyhow, it should be watching the fan/load side. What's the difference if the relay has juice but it's stuck or there's a bad connect to the fan some place? The LED should only light up if the fan is actually turning. One toggle would allow interruption of the control side of the relay, and the other toggle would parallel the fan-switch to override it. Simple circuit. Two switches, one in series, the other in parallel to either defeat or enforce that relay either way.

The LED on the load side has quite a few options, but without getting too difficult, something between an 8k to 15k resistor in series with it to ground would monitor if juice is "supposed" to be turning the fan, rather than if the fan is actually turning. They used to call things like that "idiot" lamps where i come from.

To monitor if the fan is "actually" turning with an LED would properly require a transistor in series with it on the ground side. That's where it gets to be a bit more than its worth bothering since as mentioned, just looking at the fan tells the story there. The idiot lamp is only there to warn one to pull over and see for themselves. if the lamp is on and the gauge is leaning to the right, then the bike is doing the best it can to cool down.
 
#9 ·
If you were riding in cool weather, the fan may never kick on, and it could take quite a while just to reach normal temp, if it ever does. 35mph in the summer is enough to cool mine without the fan.

Don't know if you do ebay, but there are fan switches on there reasonably priced, just have to watch for the deals. $30 is pretty high in my opinion.

A fully functioning charging system drops about 1 to 1.5v when the fan is running. So running the fan more than needed could run into trouble on a long ride.

You can test the fan sw. with an ohm meter and a pan of boiling water.
 
#10 ·
I'm so way not a tuff guy, but my garage has a palm tree that blocks the sun sometimes and has a asphalt floor if you get my drift. I think if i had a meter, the best test for that switch would simply be to idle the bike instead of pulling it out and having to refill the radiator.

Since it's only a continuity test, i might just do that tomorrow just to make a meter. Too bad Radio Shack went out of business though. But on the bright side, there are enough worn out appliances tossed on the street in this part of town that i can easily find an LED. Somebody tossed out a nice Magnavox flat screen recently that i am going to rip apart for parts. Simple continuity tester is just two leads one on that tab, one on ground, a 1k resistor, an LED and a AA battery ( or AAA or whatever works ). The switch should eventually close somewhere around the time the temp gauge starts leaning to the right.

I am SURE, however, that the oil that built up in that connector was the problem since i know where the oil came from and when. I also know that the mechanic at the shop may have ridden the bike around the block or something but certainly never got it hot enough to need the fan.... then on the other hand, since he was charging batteries that had 1.5 cells completely dry, what's the difference how hot it got when he was checking out the bike? ( shruggs )

What *happened* about a month ago, the first day i finally had her paid for and pink slip in the mail, etc... was on the way home, she only lasted about 3 miles down the road and then had what i will call a blowout. I had just begun to shift into third, clutch was in, and suddenly WWWwwwRRRRRRRRIIIIIIIIIII..... she was at max RPM which sort of freaked me out for a sec, i had to hit the kill switch, to which she replied with one seriously enormous backfire, oil splattered all over the place from several sources, and gratuitous amounts of white smoke as various fluids boiled off her fins, etc. etc.. My only choice, that far away, was to have her taken back to that shop. The OWNER of the shop, is a very cool guy and hauled it back for no charge, and thus began a month of them finally finding out that the previous owner of the bike had rebuilt the carb using his own home-made parts. They replaced the head gaskets which blew, seals, several hoses, all sorts of various things, and this is the part of the story i sort of glossed on over at the top of this thread. So... basically, i am about 99% sure that connection was simply fouled and seriously, this morning after pulling it off, it was sopping wet with oil inside and on the tab.
 
#12 ·
Lockbox mod photos: ( out of order )


First two are the finished mod, the lock installed is a common post-office box lock with a washer behind its face to give it a front face ( i.e. rather than just the bare plastic ). Had to cut a wee bit of plastic to allow the tongue of the lock into the slot better on one side. The third picture shows the original condition, a big hole and a piece of duct tape the previous owner had been using.

Total parts: ( used post box lock, and one washer )
Tools: knife, screw driver, pair of pliers.
 

Attachments

#16 ·
hey Doc



You read my mind. But i read all your other posts here too. Go figure that. Tomorrow's mission is to get that socket set and a cheap multimeter.

Have to take the bus. :frown2:
 
#18 ·
Sitting here now waiting for the "battery charger" to charge, so thought i'd login. Still waiting to kick it over.

The only thing i've seen my tach do so far is sort of bounce around between 0 and 2 regardless of how often the pistons are firing. Not sure how to pull it, but that might be something to get done today as well.

She needs lots of TLC ... Tending Loose Connectors. Found one sort of busted that runs two wires up under the fuel tank. I am thinking about just getting a set of new connectors for all around the entire bike and just re-doing every last one. It would solve a lot of time and it would get the "rebuilding" job done right. Most of them are dried up as far as plastic life goes.

:nerd:
 
#20 · (Edited)
If your rpm guess is even close, it's about 700 rpm too low. 1000-1100 rpm is spec, I think.

14v may be as good as you'll get on a stock system, which is fine. You might look at the Two Wire Mod in case it's having brownouts.

If I open the throttle at all on a start, I usually get a pop. But your description sounds worse than that. It was popping fast while idling? Makes me think of sticky valves, but the idle sounds like it's way too low.
 
#21 ·
reply and update



Way low... okay, so i found another friend with better tools in his garage, and owe at least an update... Fan problem is resolved and tested. I took her up to the valley and back today which was at least 30 miles each leg. Fan is working fine, met L.A. rush hour traffic on the way back which is sort of like a long parking lot with traffic lights in between stretching for literally 10 miles or so.

Still having battery issues. My friends charger has a meter on it. We tested a practically dead lead/acid battery he had laying around. He showed me the current readings at various settings, basically typical behavior. We tried the same on the "NEW BATTERY" i had and it would only cook at about half an amp or a little higher. Took it back to the store, replaced it, they only one other... but... found the dates on the batteries for comparison. The other was at least a year old and had just been sitting on the shelves all that time. the NEW new one ( replacement ) is only two months old, but according to specs... they need to be charged at least once per month to keep them from draining down to kaput, and once they are kaput... they are impossible to charge due to the chemical coating on the plates. After the ride today... i stopped to eat, she cooled for at least an hour. She started up again, but only after much coaxing compared to earlier. All of that traffic idling ate her charge up. She died just as i was about to turn into traffic. I got lucky it was near immediate. So i ended up getting a jump before heading home.

So now, i am thinking... this replacement new battery *WAS* charging before, so that may have only been half the other problem. I need to check it on his meter, but need to wait until Sunday for that. If it is allowing a charge, then i still have too weak a charging circuit for one or another reason. I'll know more tomorrow because i gave the battery about a half hour of charge after i got home.

Using his digital meter, though, my earlier reports were incorrect. He read my meter as well, and my report was correct, but the new meter is more than likely out of calibration. According to his digital meter, the MOST we could get across the battery at a speedy throttle ( we guessed at least 3k, more like 4k ) was about 13.6V and she backed down to about 12.2v.

We have the idle adjusted to a mutual opinion now as well. I am greedy on idle... to a fault. I am always worried an engine is idling too fast. His ear said different.

Took the extra day to get the correct spark plugs as well. The over the counter guy at first gave me the "generic OEM" for the part number, champion plugs. Back at the garage we compared them. Night and day. The generic plug according to O'Reilly's catalog database has an electrode stem about HALF the height/length of the stock plug and about 1/3 the depth toward center. The plugs that came with the bike were all a mixxed set, only two were the same, and only one was the stock part.

Got a used set of saddle bags up in the valley. Going to have a little wrestling match with them tomorrow as well. The strap that lays over the fender under the seat is keep int the seat from getting close enough "down" to bolt her back in from the rear. There are three small upholstery shops about a block away from where i live. Time to go make some new friends, solve that problem and see what they think about bike seats.

:nerd:
 
#23 ·
I babied my battery the first couple of years, but this winter it's just been sitting out there in the cold. Bike started right up last week.

If mine is warm and sits about 15 minutes, I need the choke to make it fire right away. (and no throttle)

If the jump starts have been from a running car, there's a good chance the R/R could be damaged. Engine needs to off on the assist vehicle to prevent R/R damage.

Your idle voltage is too low. Best to test the stator and r/r step by step. R/R = Regulator/Rectifier. Instructions are here on the site, and in the repair manual which can be downloaded from here, free. 12.3v at idle for very long will give you a dead batt., especially with the fan running.

A lot of us here run a dash mounted voltmeter to monitor the charge.

There's some chance the Two-Wire Mod could help, but the headlight anomaly hasn't been solved yet.
 
#24 ·
I posted about the 2-wire mod... was going to try it... it might be better to say what points in the electrical system the wires are coming from rather than color-codes. If i knew that, i'd be able to trace it using the manual. I have a black/yellow wire. I do not have a black/red wire to that plug as stated in the mod. I can't even find a black/red wire in the service manual on that plug so i can't reverse-engineer what the mod is trying to achieve. :/

I put in new spark plugs this morning. Still getting a pop=pop=pop sort of light backfiring on deacceleration. She has sort of a song rythm to her idle instead of simply a smooth consistant idle. lum-lum-lum-lum-pop-lum-lum-pop-pop repeat. So i know its to the carb thread after this charging issue is solved. ;)


Can't do the two-wire mod. I am pretty sure the idling in heavy traffic is keeping her from charging... and she is charging "ok" when the fan is off, as you mentioned. So the two-wire mod is very attractive to me right now as something to try so i can at least get a strong charge for "normal" operation. Avoiding the rush-hour is something i can live with and deal with in a pinch.
 
#25 ·
Responded to you on the Two-Wire thread.

Your idle may still be low. These engines do not like low rpm or slow idle. When riding, 2200-2300rpm is about as low as you should run, it hates low rpm lugging and loves revving high, 5500rpm (and higher) is nothing for this v-twin.

Can you post a video so we can hear it?
 
#26 ·
Made two videos. The second vid was made after i pressed the "start recording" button on my phone. The first one was made BEFORE i pressed "start recording" ( grins )

So, the bike is already warmed up sufficiently to about half the meter... vertical pin... at the start of the video. Couple minor things to note... when starting, if she is leaning on her kick-stand, she *needs* to have the choke on or she will die. When vertical, the choke can be turned off and as soon as i get on her, straighten her up, she starts to idle at about 4x whatever she was doing while leaning.

As soon as i figure out how to get the video off my phone... to all of the middle=men in between, then here. i will post it. It was too large to mail to myself like a photo.
 
#28 ·
Long story short, ( just ask if you like long stories ), i am going to need a crash course on carb "tune up". Am i going to need any special tools?

The shop mechanic "owes" me this "tune up" and he's the dead last person i want within 100 yards of my bike.
 
#31 ·
No, the decel pop can't really hurt anything. A huge concussive backfire could possibly split a muffler, but the decel pop isn't normally that strong. Might shake some carbon loose, but that's good.

Mine had a pop-pop on decel when I first put it on the road. It went away, was thinking the coast enrichers were sticky, but have never been inside my carbs. I tried to get it back by removing the right side vac port cap (capped off for earshave). All I got was a couple of really huge backfires coming down long mountain descents. I capped the vac port.
 
#32 · (Edited)
Anybody had a coolant fan blade break loose from the coolant fan motor shaft?
This just happened to my son's 2005 750.
I assume a rock or stick got wedged in the blade but I don't know for sure.
I reckon it's remove the engine guard, drain the radiator and remove to get to the coolant fan assembly.
Probably get a fan blade from ebay or maybe a whole assembly.
May as well vinegar the system while we're at it.

Does anyone here recommend Engine Ice coolant?

Any comments on the fan remedy?

Do you know the method of blade attachment to the fan motor shaft? Snap ring, roll pin, set screw..... glue... rubber band?

Thanks!
 
#33 ·
We took it on this afternoon.
Took about four hours.
Bike cool and on center stand.
Disconnected negative wire from battery.
Removed fuel tank.
Removed radiator drain plug.
Opened radiator cap.
Disconnected top radiator hose from thermostat housing.
Remove all bolts from stock engine guard, except for the bottom bolt holding the chrome strap behind the right exhaust pipe.
Tilted foot brake bracket backwards and tied off with wire.
Tilted shifter lever bracket out of the way
Pulled some slack in the clutch cable left side to slip top of engine guard around.
Removed radiator shroud.
Removed radiator bolts.
Required some prying and wrestling but was able to get left side of engine guard to swing out toward front tire. Right side engine guard could not be removed because of bracket pinched between right exhaust pipe and frame. There was enough room to swing left side of engine guard out far enough to tilt top and left side of radiator out enough to remove radiator fan assembly.
Tilting the top of radiator forward required one person pushing on the top radiator hose with a screwdriver at the thermostat housing and the other person pulling on the top of the radiator.
The fan assembly was removed with four bolts and the electric wire disconnect. One bolt on left side had a ground wire to fan.
The fan blade attaches to the electric motor with 3 screws. Still don't know what caused the incident but the metal plate with the 3 screw holes was molded into the plastic fan blade by manufacturer. The plate had spun and melted the plastic. Motor still good.
Had ordered used fan assembly from ebay for about $35 and arrived today.
Motor tested good but since our motor was newer, removed fan and attached to our motor.... screws with blue locktite.
Got it all back together and since coolant was clean, added new.....burped and road ten miles. Everything normal.

Thank you guys for the various posts that I've read which helped in many ways to accomplish this repair!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top