Total Motorcycle Community Forums

When my bike (Yam xs400) is idling, I get 13.26 volts on the battery. Now the thing is Im using a car-battery to run my system... my motorcycle battery was crap.. and I wanted to get the bike up and running first.

Apparently the stator and rotor resistances are fine. Now is the lower voltage only because its trying to charge a larger capacity battery... or will I now have to check the rectifier and the regulator??? I had the bike idling for about 20 minutes on the car battery, and the voltage on the car battery did not drop ... so Im assuming that some charge is trickling through... any guesses as to what the problem might be???

While the bike was running, I did momentarily disconnect the battery from the charging system... and the idling speed promptly increased.. so some load was definitely taken off the charging system. Also I do believe that the charging system on an xs400 is the non-permanent magnet type alternator.. so current is definitely drawn from the battery to excite the rotor coil.

-Thanks

I think 13.26 is very good for a bike of it's age.

Especially charging a bigger cell battery such as a car battery!

I wouldn't worry to much about your charging system looks to be doing just fine.

almost sounds like your bike needs to be taken out for a "Relief of sitting run".

Good Luck!

Great Job!

"Always remember to replace the oil you drain out" Ouch!!!!

Hehe, on an unrelated note... my bike is smoking from someplace other than the exhaust. I had it running and noticed that smoke was wafting out from the cooling fins on the left cylinder head. Now I dont beleive that its major... maybe a head gasket needs replacing, plus there seems to be a film of *Reaaaallly* old oil spilt over the fins...maybe that just got cooked and started smoking.

So my question is whats the best way to clean the engine exterior without getting it out of the frame?? I'm almost tempted to spray it down with a hose along with my yellow lab.

The oil leak may be a from a head gasket, but it could be a valve cover gasket too. Engine degreaser sprayed on it (cool engine) will help remove the gunk. Also a bottle brush. Do they still sell those? Anyway, when you rinse it off keep the pressure down - you don't want to force water into places where it doesn't belong.

on them old ones checking voltage while idling aint gonna tell you much--increase rpm and see if voltage increases.as for that oil leak if you aint too particular about shiny you can use Easy Off oven cleaner on it.

Yup,
It goes up all the way to 14.3 volts. So I guess Im good for now. Thanks.