TOPIC:

The bike is Rose's '96 VN750 Vulcan with roughly about 15K on the odo (12,345 when she got it...odd mileage, huh? ).

It was dealer serviced the entire time the PO owned it, and never had any problems during that time that we're aware of.

It had sat unused in a garage for just over a year before Rose got it. And since then I've had to pull and thoroughly clean the carbs (the foam from the 10 year-old air filters desintegrated and got sucked into the carbs, causing the front cylinder to flood with fuel ), replaced the stuck and worn carb air cut-off valves (they limit backfiring on deceleration), new spark plugs, and have done the normal oil/filter changes and bearing/pivot point lubing.

Just before we left to Vegas I changed the oil and filter, and drained the rear diff fluid and replaced with new. I never touched anything electrical and it ran fine up until then, so I'm completely perplexed as to why it's acting up like it is.

The only thing out of the ordinary is that it had a slight knocking sound (more pronounced and noticeable at idle) in the front cylinder, which I figured was a worn or stuck cam chain tensioner.
I removed and examined the cam chain tensioner and didn't really notice any excessive wear or problems with it, so I unloaded the tension on it (it won't go back on w/out doing this) and re-installed it.
Strangely the knocking sound dissapeared!
But after about 200 miles it is making the sound again.
I'm guessing that it is indeed worn, and is reaching it's extended limit and "locking" into place.
If it weren't for the fact that Kawi wants $90 for a new one, I'd be willing to just replace it to see if that is in fact the problem.

Anyway, there's something that is literally sucking the power from the battery.
I fully charged and installed a brand new battery and it worked fine for about two hours, but now that battery has been sapped enough it won't crank the bike over. I've recharged and checked the battery and it's in good condition, so I've ruled out it being a defective battery.
I've also done a quick visual inspection of all connectors and the entire wire harness for signs of a
dirty/bad connection or pinched and/or grounded out wire, but haven't found anything wrong.

I'm horrible at diagnosing electrical problems, since it involves numbers. Numbers=math, math= migraines and hurling tools and other potentionally damaging objects at just under the speed of light.

I'm thinking that either the regulator is dying/dead, or the stator is damaged and shorting out....or both problems!
Obviously there's something somewhere on Rose's bike that is killing the battery. Fixing or replacing what's causing this problem is the easy part, finding it is where I'm having probs.

Ok electrical gurus (loudhvx?), I really need your help and advise here.

First step is recharge the battery and take some voltage readings.

Disconnect it from the bike and charge it.
After it's charged, let it sit for a half hour. Take a battery voltage reading.

Then connect it to the bike and measure the voltage (Don't turn the bike on yet.)

Then turn the bike on (but don't start it) and take a voltage reading.

Start it and then measure the voltage on the battery while it is idling and while it's revving at 4000 RPM for 10 seconds or so.

We'll go from there.



Post edited by: loudhvx, at: 2006/09/24 14:04

Most charging problems can be attributed to:

1. dead cell on battery
2. loose wire/connector or very dirty wire/connector
3. bad reg/rec
4. bad alternator

If the battery is OK, remove the wires leading to/from the reg/rec and spray with contact cleaner and apply dielectic grease. Find the end of the negative battery cable and it will likely be bolted to the engine. Check to ensure it is snugly by tightening the bolt. Check the end at the battery for tight and clean and put some dielectic grease on it. Then check the POS battery cable which goes to the solenoid lug. Make sure it is tight/clean. There will be a WHITE or WHITE/RED thick wire going to the solenoid lug. This is the wire that keeps the battery charged... follow it back and make sure it and all its white and white/red buddies are clean with contact cleaner and apply some dielectic grease. OK... you have done that and the problem is fixed... great but if it isn't,

Go to loudhvx's next set of voltage tests at the battery. After charging, check voltage at idle and at 4K rpm. A sign of a defective reg/rec is low voltage or high voltage when the bike is revved up. Should be about 14.5 VDC at 4K rpm on a baby bubf. If not and it is lower, then your alternator may be tired but if it is higher, the reg/rec is likely puking. Those guys are hidden out of the air flow on that bike and tend to run hot which shortens their life (as I recall). If you need help finding the VN750 web forum, I am a member there although I don't hang out very often... they can help locate a replacement. If the problem appears to be in the alternator, I am not real sure which type you have but first step would be to check AC voltages while the bike runs.

I just wanted to give an update on my findings.

I performed all the suggestions and tests.
Even with my minimal knowledge/experience on electrical, it looks like the stator is 100% dead.

Just for sh!*s and giggles, and to see if the engine knock could be 100% identified, I took it into the dealership I once worked at to have them give it a once over.

Dead stator, and the front cam chain tensioner was indeed worn to the point of locking into place extended.
The only shinning point to all of this is, that my initial diagnosis of what was faulty was dead on.
Call it blind luck if you will, but I'm calling knowledge through experience.

So I figured, how hard could it possibly be to swap out the stator and cam chain tensioner.
I checked the repair manual on CD we have for her bike, and it states the motor MUST be pulled to replace the stator!
The motor actually sits below and in front of the frame tubes, which does require engine removal to even be able to get to the stator - listed as being a 4 1/2 hour job.
Not really wanting to mess with it, and already having enough projects to keep me busy the rest of this year anyway, I checked with the dealership and was quoted a parts and labor total of almost $1,300 (which included the initial estimate)!

So the search began.

I lucked out and located a NOS aftermarket stator on eBay with a 1-year warranty for only $133.00 shipped - Kawi wanted almost $400 for it, and only offered a 90 day warranty on it!
So I asked the dealer the cost for a NOS tensioner, and to just replace the stator with the one we supplied.
Long story short, $700 plus the $133 for the stator and Rose is a happy camper and riding her baby once again!


Thanks to WG and Lou for the help and suggestions, it was very helpful and greatly appreciated!

Wow! Glad to hear it's back on the road!

Like you said, at least there's the piece of mind of a spot-on diagnosis

Rx4... The tensioner was worn? How? Never saw a worn tensioner on a Vulcan. Typically the cam chain stretches a tad and the OEM tensioner can't extend far enough. This is common on most Vulcans; so much so, that Kaw Canada has a replacement tensioner that extends a bit farther than the original and this tensioner works on the bigger Vulcans... not sure on the 750. The engine needs to come out on a Vulcan to do most anything due to lack of clearance in the frame. You can do SOME things by removing the motor mounts and dropping the engine some... like on the cylinder head (say a valve cover starts leaking oil...) It isn't that hard to pull the engine by yourself with a tranny jack. Put a piece of wood under the engine and once you have the frame member on the side removed, and the motor mounts, you can pretty much roll the engine out using the jack. The larger engines are fairly heavy so it is nice to have a second strong back at this point to put the engine on a stand. They can be set in the middle of a furniture moving dolly to do whatever work is needed and stay in place nicely.