electrical issues and gas smell in oil

[moorishone]

I am having some issues. But first hello everyone...
My 1979 yamaha xs400 has given me quite the headache the pay few weeks. As follows:

1. My battery is fine but when I start the bike and ride it get to my destination shut it off I have to recharge or jump the battery to get it running again..

2. I took the stator off to check if it was burned but it's not. In doing so I lost about 3 quarts of oil out of the stator area. Is that normal?

3.my oil kinda smells like gas. Is that normal?

4. I believe after testing my voltage while reving the motor the voltage stays at around 13 volts, also when checking the voltage when shutting off and starting motor battery stays the same. Which leads me to believe that my bike is running solo on just the battery. Now I have to figure out what is wrong next is it my rectifier/regulator or is it my relay? Something isn't sending power back to the battery and is causing my headache. Can anyone assist me with ideas and/or solutions

 

[moorishone]

Here are pictures of my 3 guesses at what is wrong

 

[arfstrom]

You forgot the 4th thing. Cannot tell from here, but the wire that comes from the stator, where it comes down under the engine, it usually gets frayed, and very brittle. Otherwise on the left item is your voltage reg, the #2 item that fails. The middle item is your Rectifier. Test it per the manual. Starter seloniod should be fine.

Check out the drewpys rewire on the Homepage, and under Tech. there is an excellent example of the shot wire being frayed. there are others photos on here, and they all are a sign of re-wire in the future.

 

[Lou Ranger]

Hello and welcome.

Here is a thread with some similar problems - might be some info on it that will help you diagnose: http://www.xs400.com/forum/showthread.php?p=118892#

Gas in the oil sounds like a separate problem - I think caused by carb floats. Whatever the cause, don't run it without changing the oil and stopping the gas leak.

 

[arfstrom]

For purpose of examinging that wire, you should pull that wire all the way off. I found it was easier to mark which pin's go where, and pull the pins out of the connector, so you can get it under the engine. even if you don't go that far, you should pull as much down to validate that the wire isn't fried. (I am very opinionated that wire is fried out, and Voltage reg's are shot after 30 years. ) But you should still use sound reasoning to make that judgement. once the connector comes to the bottom of the engine, you can see and feel, and hear the crackle of the brittle wires, and typically its under the rear part of the engine, where the wire comes down and out of the drive shaft cover, and pops up. by pulling that wire and connector out, you will see the fray'ing. I think I am repeating my self. Its a habit on this forum. Like Lou said, the gas smell in the oil, is usaully a sign of a bad float. chances are you can smell gas, in the air filter. personnally I had a bad float, that after cleanning It would run, then tomorrow, it would be dead. the float had a small leak that over night would fill up, and then it would flood out the system (crank case/air filter) Soo good luck

 

[HoughMade]

They've covered the electrical and gas in the oil thing.

All I'll add is that taking the stator cover off on the side stand will cause you to lose oil. This is one reason these things came with center stands. On the center stand, oil may drip out slowly, but it won't pour out, assuming you have the right amount of oil.

...which brings me to my last point. You should only have slightly over 2 quarts of oil to begin with. Gas in the oil could be the problem or simply overfilling the oil.

 

[moorishone]

Thank you guys. I will start my trouble shooting now.

 

[Hishman]

Heres a good plan of attack

1) Test field coil by turning the key on and placing a razor blade or small metal object against the alternator cover. The filed coil should power on and magnetize the object. If it does cool move on if not unplug the field coil. Briefly run the black wire from the connector to the - battery terminal and the other black or green wire(whatever yours is) to the + side. This should bypass the regulator and power on the coil. If the coil still doesn't magnetize its broken or need to be rewired.
2) test the alternator armature. Unplug the alternator armature test the ohm between the three white wires. If its not .72 +/- 10% it is broken or needs to be rewired
3) Test the rectifier. Unplug it. Put your multimeter on on of the leads and test each individual prong. Either they will show no continuity or vise versa. Now go to the other lead and check all the prongs again. They should be the opposite of the first test. If one or more has continuity both ways or neither way replace the rectifier.
4) I never could find a way to test a solid state regulator so i just replaced mine. If yours is mechanical there is a way in the manual.

This should give you a good start