Yamaha Virago dim lights...

[82Stang]

Hi,

1986 Yamaha Virago 700cc 2 cylinder bike.

It has been sitting awhile and when started and run, it was running rough and fouling the plugs after 20 minutes of running time. After riding down the road, it started to run rough again and I turned back. When pulling in the garage, I noticed the lights were dim while I was on the gas. I shut it off and it just clicked when trying to start again. Is the problem something to do with charging? What kinds of things should I check here?

Thanks.

[jeffcoslacker]

Regulator rectifier or stator may have failed...obviously it's not charging at all.

Sometimes stator windings' epoxy insulation will crack over time, especially when not run for a long time, and fall apart and short out when the motor runs again...

Make sure a mouse or something didn't get up in there and chew the wiring from the stator (in the engine crankcase) to the reg/rec (usually under a side cover and near the battery) or the wiring from the reg to the battery. Check all the fuses.

There is a way to check the stator for output and shorted windings, but it's a bit involved to get into here....once you locate the reg/rec look it over closely, sometimes it's pretty obvious if they're smoked, they look burned or have the insulating snot running out of them...check it's connectors too, sometimes one will be burned or melted, or have water/corrosion in it.

If it's a typical setup, there will be three wires of the same color coming from the stator to the reg...umplug that connector and look for scorching...any burns probably indicates a shorted stator. A quick verification is to probe those 3 terminals with an ohmeter, going from the terminals on the stator side to the engine case. There should be no conductivity between stator leads and case...a reading indicates a winding shorted to the case (grounded)...in that case the stator would have to be replaced.

There should also be no condictivity between any of the three terminals and any of the others of the three, if so, those two phases are shorted together. Bad stator also. Each one of those wires should produce a voltage reading equal to 1/3 of the total charging output, so if you read 4.5 volts each at idle, it's producing 13.5 volts total, more than enough, and ouput should increase with RPMS...bikes typically don't put out much charging voltage at idle, so you may not see more than 12.5 total or so output from the stator at idle, but if you only see like 3.3 each (9.9V total, less than battery nominal voltage) or something, or differing amounts between them, or no increase as RPMs rise, you've got stator problems...if all that checks, the problem is on the reg/rec end of the system...

Whadda you know, I guess it wasn't too much to go into here....

Make sure your grounds are good too...sometimes from sitting they corrode up.

[82Stang]

Hey, thanks for the info.

Excellent detail and directions to solve my problem.
Appreciate it.