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Discussion Starter #1
Hi all, I'm new here. Posted a greeting on the newbie check in.

Tuesday I bought a 1986 vn750 with 20k miles on it. Short ride mostly practicing take offs on Thursday evening, and the same again Saturday morning. Saturday evening I took it out for my first ride for about 35 miles.

The bike seems to be acting like the battery is dead and drained when the bike is hot.

Unless my perception is messing with me over coincidences, the bike does not want to turn over well, if at all. But only when it's hot. It even backfired after yesterday's 35 mile ride when I tried to start it after it had died. After sitting for a couple hours it started turning over and cranking again. I've tried it several more times today. (cold each time) and each time it has turned over and with some finessing of the throttle it does start. It does SEEM to be getting a recharge when it's running or it shouldnt restart after it coos off. It has been a little stubborn to start since I bought it. I have read that is KINDA common with this bike and I'm sure the fact that it's 21 years old probably has a few factors attributing to the stubborn start. It's the problems that seem to come on after it gets hot that are concerning me. I'd hate to ride it somewhere and then break down stranded.

I have a friend who is a moto mechanic but he's aweful busy and has not had time to give the bike a look. Even when/ if he is able to come look at it. I dont want to burden him with a bunch of free labor trying to work on my bike. I'm hopeing he can look at it and recommend a few critical things I should be looking into gettign done. In time I'd like to learn the ins and outs of the bike and do most of the work myself. I have very little mechanical experience but I do somewhat understand the various functions of things like pistons, starters, plugs, tranny ect. I have a willingness and ability to learn. The bike did come with a 1995 edition Clymer service manual (M356)

I have read a lot fo the verses stuff and also threads on what to look for and do with a used 750 purchase as well as first maintainences for the used bike. All around fluid change, check valves, tune up, plugs, wires, battery ect. I have not yet performed any of those used mainainces but I will as funding provides.

Anyone have any idea why the bike seems to act funny sometimes? I have not ruled out that it could be just a weak battery, but I just dont know.
 

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HAWK
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do you have a volt meter, if so check the voltage of the batt when running.
Should be 14volt with the RPM over 2000.
If not I would start checking the stator and R/R
Then if all is good replace the Batt with a Maint free one.
 

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and the Adventure Cycle
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replace the Batt with a Maint free one.
Along with that, make sure all the connections for the battery (including the frame ground wire) and to the solenoid & starter are clean & tight.

Hopefully it's just a weak battery issue :smiley_th
 

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Premium Member
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Ditto on what both of them said above. If the battery is bad, maybe a shorted couple of cells, it might take on some charge, but will be weak, and a bad battery can cause you all kinds of grief. Your starter could be dragging as well when it is hot. They pick up lots of oil spillage and road grime over the years. A dragging starter motor will certainly take it's toll on the battery, especially when the engine is hot.
 

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Benjammin'
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421 Posts
Cleaning your battery terminals and all the connections after that point are best bets for low-cost troubleshooting. I used sandpaper on all the terminal connections (all surfaces) to make sure they are good and clean.

As long as you have the battery disconnected, it may be a good idea to take it to a auto parts store where they can check it out for you. If you are told it is bad, do not buy one that is maitenance free! The recommended battery is a MF battery, or specificaly absorbable glass mat (AGM) to keep your bike happy. I believe all the information for batteries is in the verses.

Goo luck and keep us posted as to your progress! We are all here to help (some much more than me) :eek:
 

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If you are told it is bad, do not buy one that is maitenance free!
You went on to say buy one that is Maintenance Free, which is I know what you meant to say above! Yes, an MF battery is what you want to buy!:smiley_th
 

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My bike acted the same when I bought it. I had the battery tested and was told it was no good, so I bought a MF battery and still had the same problem. Mine turned out to be the r/r going bad. It was find when the bike was cold, but when it warmed up it would stop charging.

If the battery doesn't work, check the voltage across the battery while the bike's warm and see what you're getting. If there's a problem you can check the verses for procedures for testing the stator and r/r.

Good luck.
 

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Mine ended up being a shot battery and a poor starter.
 

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"My bike acted the same when I bought it. I had the battery tested and was told it was no good, so I bought a MF battery and still had the same problem. Mine turned out to be the r/r going bad. It was find when the bike was cold, but when it warmed up it would stop charging. BIG T"
I had the same problem i changed the battery to a MF battery and still had the problem. So after the final straw being stuck at a gas station for over an hour, I took the bike in. Well it was not the r/r (which i have relocated) or pick up coils. It was the starter, so if you have changed some stuff and it hasnt worked have your bike looked at to see if it was the starter.
 

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Benjammin'
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Fergy,
Thanks for the catch. I meant to say do buy the maintenance free battery. (I was quickly typing this post at work, hiding from the boss).
 

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Discussion Starter #11
Thanks for the tips all. I really apreciate it. I will give the hands on sugestions a try as soon as I get a bit more time. I'm working late this week to make up for the holiday. (have to, not want to)

As funding becomes available I was hoping to make some of the other suggestions happen over time.

Here's a bit of additional info for thought.

I took it into town this morning before work to run some errands. Before I left I charged it on my truck via jumper cables for about 30 minutes. Went just up the road got it inspected. Shut down and restart. Went to the bank, shut down and restart. Went to the DMV to get my endorsement, shut down and restart twice. Brought it home and parked it for the rest of the day. Shut down and restart. Each time there were no problems. Again perception may be messing with over pure coincidences but it SEEMED to run better today too.

I got home from work too late to mess with anyhting. I picked up a Black and Decker "smart" charger from Wal-Mart and hooked that up. We'll see tomorrow if does any good. I plan to take it to work.
 

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Discussion Starter #12
Charging overnite seems to have no effect. As far a I can tell it just doesnt seem to want to run when it's hot. If I rev it a little it does keep it from dying. As long as I am in gear an moving it seems to keep chugging down the road.

Including today's July 4 joyride, I've acumulated about 100 miles of seat time.
 

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Mine had the same problem. I turned the Idle up a very small amount and added 3 tbs of seafoam to my tank. It now starts while hot with only a touch of the starter. Wouldn't hurt to try some.
 

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i know what you got man

hey,
I had the exact same problem man.
Found out that my R/R was fried....My advice is to get a new one quick before it kills your strator.
By the way, the R/R form a Kawasaki ATV is the same as what goes on our VN750 ...plus it's $50 cheaper.

good luck.

PS: buy also a new battery , the one that you have is most likely dead cause of the R/R .
mine almost blew up
 

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and the Adventure Cycle
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Here's the R/R testing instructions from the Vulcan Verses......

If you have the Kawasaki Service Manual, you will find R/R checkout on page 15-18. If you don't I will list what is there for you. Quoted from the manual as much as possible: Regulator/Rectifier Inspection Remove the left side cover. Pull out the connector. Be sure to set the hand tester to the 100 ohm range and zero the meter(Not necessary on a digital meter) Check the resistance between the regulator/rectifier terminals as follows(there is a chart and picture in the manual which I cannot reproduce right now but I will try to put it in words for you)

A1 A2 A3 All Alternator Terminals --- --- --- Connector with pins facing you and notch at bottom --- --- ---

G M B, G = Ground M = Monitor B = Battery --|__|-- (Hope that came across right)

Measure B to M - should read infinity

Measure B to G - should read infinity

Measure B to A1, A2, A3 - should read infinity

Measure M to B - should read > 10K ohm Measure

M to G - should read > 10K ohm

Measure M to A1, A2, A3 - should read > 10K ohm

Measure G to B - should read between 0.4 to 2K ohm

Measure G to M - should read between 1 to 5K ohm

Measure G to A1, A2, A3 - should read 0.2 to 0.6K ohm(200 to 600 ohm)

Measure A1, A2, A3 to B - should read 0.2 to 0.6K ohm(200 to 600 ohm)

Measure A1, A2, A3 to M - should read infinity

Measure A1, A2, A3 to G - should read infinity

If there is more resistance than the specified value, the unit has an open lead and must be replaced. Much less than this resistance means the unit is shorted, and must be replaced. Hope this helps someone out there.
 

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Benjammin'
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Great post and description!

I am inexperienced at the R/R so I have a couple of questions for my clarification. In your post, is the G,M,B terminals on the R/R itself? And, is A1, A2 and A3 in the plug connector?

Lastly, should I run this check on my bike if I currently don't appear to have any charging issues? (I know I will now that I made that comment :doh: )

Thanks again!
 

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Discussion Starter #18
Thanks for the tips everyone.

Last night I pulled out the battery, cleaned the connections. There was deffinately some corrosion going on inside the battery box but it appeared that it's been there a long time. Maybe from a previous battery? I didnt see any wiring below the battery box....... but I admit I didnt go on an extreme hunt for wires.

I'll get on to new battery and R/R testing soon as can. As well as stator location.

Need tires, brake bads, fluid change and probably a tune up. I'd really like to get the valves checked too. Need new hand levers, grips, mirriors and lots of TLC.

Oh and I DID concider the possibilty of perhaps a slight idle adjustment? Thanks to dsr for reminding me.

I am hoping that this doesnt become a lesson in frustration but I am perfectly ok with this being a fixer upper/ cleanup project.
 

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and the Adventure Cycle
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I am inexperienced at the R/R so I have a couple of questions for my clarification. In your post, is the G,M,B terminals on the R/R itself? And, is A1, A2 and A3 in the plug connector?
I attached a pic from the service manual. The terminals are all on the R/R itself.
 

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