Need help diagnosing please.

[goatman]

I have ignored my vmax for awhile, but am trying to get it on the road again and have an electrical issue. I have a new agm battery with 13.18 volts at rest. When I start the bike, it drops to around 11.8 at 2000rpm. I am going thru the diagnostic flowchart from this site. When I check the red rr wire with the multmeter at idle, it shows -.34. When I check the black rr wire, it shows 0.0.
When I check the 3 stator wires for resistance, I get 1.8 on two of them and 2.4 on the third. The flow chart tells me that 2.4 is too high and I need a new stator.
Can anyone give me some insite on this data. I am wondering about the negative number on the red rr wire and the 0.0 for the black. Thanks for any help.

 

[sdt354]

Do an a/c voltage check on the stator wires at the plug, check the plug contact condition. Check all 3 wires, one to another and report back with the readings. It sounds like it could be a bad R/R or ground on the R/R.Later model(96 and up) with a ground wire on the R/R and large heat sink works best. A ground can be added to the old style too, R/R frame to battery or good frame ground. The peg bracket grounds the older style R/R and usually corrodes causing this type of problem. Clean is the word. On the right side of the frame, near the battery, there are 3 black grounds. Remove the bolt and clean them, put something on them like wd-40 or dielectric grease even better. Did you do the crimp fix yet? It should be done regardless.The plug connection on the red wire out of the R/R should be inspected and cleaned too. Very common problem on a Vmax, lots of threads to read.
Steve-o

 

[goatman]

I have done the crimp fix, and upgraded from the 91 rr to the newer style. I did some more poking around, and the ground on the right side that attaches down by the oil filler is in rough shape, especially the smaller wire that that comes off the larger one is very brittle with a few broken wire strands. I could not find that part on any of the parts fiches, ie bikebandit. Is that something that I can have made up at the auto parts store?

 

[PATMAX]

Yeah no problem cutting off lead to section were all wires are good. Insulation strippers are nice and a drop off solder is nice too! Just make sure you leave enough length. Consider a small bit of shrink tubing too.


When in doubt...Gas it !!!

 

[MaxMidnight]

A couple of points.

Before trying to do any diagnosis make sure the basics are right, i.e. all earths and connections are in good condition.

Battery voltage = 13.18 volts. A fully charged battery would normally read around 12.6 volts.
Whilst yours is reading high there could be a couple of reasons for this.
i) You have measured the voltage just after the motor has been running and the battery still has a 'surface charge'. This needs to be dissipated before you can get a correct reading - turn the ignition on, lights on but don't start the bike for a minute or so. Turn the ignition off and re-measure.
ii) Your multi-meter isn't very accurate.

Quote "I get 1.8 on two of them and 2.4 on the third".

The resistances should be between 0.33 & 0.48 ohms @ 20 C. Either you have not read the meter correctly, have high resistance or your meter is Donald Ducked.

Not sure which flowchart you refer to but you may like to check this one out.

Finally, you don't say what the problem is. e.g. poor starting?

If, after running the bike, the battery shows 13.18 V then that would suggest that the charging system is working pretty well as intended.

That said 11.8 volts @ 2K is too low but would not account for the reading above.

Could you a) Advise what is problem that you are having and b) Re-run the tests using another meter?

 

[goatman]

Thanks for the replies. The initial problem is the battery becomes discharged while riding. The 13.18 reading from the battery came after an overnight on the battery tender, which accounts for it being a bit high. I am admittedly not good with electrical problems, but have decided that the first thing I have to do is replace/repair the two wire ground on the right side of the bike that attaches down by the oil filler. Maybe that is my whole problem(probably not the way things have gone with this bike). I will report back after I do that. Thanks again.

 

[goatman]

Well, I had a guy in our mechanic shop at work repair the ground wire on the right side of the bike, and it is still not charging. I am not good with the multimeter in terms of understanding exactly what I am doing, so bear with me. I checked the stator wires for continuity to ground after reading that this is another test to see if the stator is ok. The lowest reading on my multimeter for ohms is 200. Set on that and grounding the black lead, I got readings of 5.1, 5.1, and 7.2. Does that tell you anything? Other than I don't know what I am doing! Also set the meter to AC and 200 was the lowest setting. Revving to 5k, I got readings of 12.5, 12.5, and 6.2.

 

[Rhoy Carter]

I believe the a/c output on the stator wires should be around 50/60 volts

 

[naughtyG]

The stator coils resistance (measuring between 2 of the 3 wires coming out of stator) should be 0.42Ω +-15% @ 68F temperature.

Set your multimeter to Ω x 1 if you can, and it should read 0.42ish

With the engine running, multimeter set to AC voltage, again between any 2 of these same three wires you should get up to about 45-50V when revving the motor up.

If your stator coils are out of spec and/or you're not getting the right voltage, you'll need to replace your stator. It's not enormously difficult but there are some right bitches of Philips screws to get out - not a chance without an impact driver. Ask Sean he may sell them, I got mine from fleaBay brand new like this: http://www.ebay.com/itm/YAMAHA-VMAX...Parts_Accessories&hash=item43ad705337&vxp=mtr