Newbie to Bikes, and XS400

Another quick update. Just got back from picking up some parts from a guy out in the country. He had a bunch of parts from an 82 that had... wait for it... 960 original miles on it. It was last registered in 83. Crazy. The bike didn't have a title so the guy parted out the stuff he didn't need and was planning on using the engine in a racing lawnmower. He ended up not using it and had it laying around along with some other parts. He wanted to get rid of them so he gave us:
The seat
Carbs,
Engine,
Tank,
Exhaust,
And speedo

All for the low price of $325. [emoji16] the carbs and the seat look damn near brand new.

So now my dad and I can go riding on our XS400's! Really excited for the weather to start warming up. [emoji4]
 
Okay, so got the new shiny motor swapped over. It's not charging. Grr. I can't believe the stator wiring is toast with it having such low miles. The charging system was working good after I got a new RR with the old engine, also rewired the stator.

I checked the resistance between the three stator wires and I'm getting 1.0~ ohms. Which is out of the +/-10% of 0.72 ohms. So I'm guessing there's something up with the stator wiring.

Anybody have any advice? Is the 1.0 ohms enough to be an issue? Thanks.
 
What kind of meter are you using? If it has a large error itself, you might not be as far off from the .72 ohm as it may seem.
 
You can check whether the meter is calibrated for its probes properly by touching the leads together. Often the reading will be slightly higher than 0.0 ohms.
Subtract the reading you get between the leads from the reading you get from the stator wires and you'll have a more accurate number.

Either way though, if all three readings are very close your wires are probably ok.

Have you checked the field coil resistance? Razor blade test?
 
Good point. I forgot about the resistance of the meter itself. I haven't done the razor blade test yet not have I checked field coil resistance.
 
You can check whether the meter is calibrated for its probes properly by touching the leads together. Often the reading will be slightly higher than 0.0 ohms.
Subtract the reading you get between the leads from the reading you get from the stator wires and you'll have a more accurate number.

Either way though, if all three readings are very close your wires are probably ok.

Have you checked the field coil resistance? Razor blade test?


Okay, so I touched the DMM probes together and I was getting 0-0.1 ohms. Thus putting the stator wires at 0.9 ohms. A little closer to the specified 0.72+/-0.072 ohms.

Checked the field coil and got 4.1 ohms, which is within the specified 4.0+/-15% ohms.

Also checked the rectifier portion of the RR and that passed the diode test. So current is flowing in the right direction.

Passes the razor blade test as well. Lol

ImageUploadedByTapatalk1431615534.934594.jpg

When I rev it to 5k rpm, it shows about 15.5v and at 2.5k rpm about 15v.

Then while idling, it drops to 12.5v and slowly falls. So to me this sounds like a regulator issue, no?

But I have a combined Regulator/Rectifier, so I'm not sure why it would be an issue.
 
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Just a quick little update. Got a used regulator from eBay installed. Bike is charging like normal again.

Also, got my master cylinder rebuilt. Last year I couldn't get it to build up pressure no matter what I tried. Same thing happened even with the OEM rebuild kit. So I investigated. I figured something had to be wrong with the master cylinder. Thankfully I had a spare one that was working properly. I looked inside and noticed that there are two holes inside the reservoir. The one on my bike had one of the holes plugged up for some reason. So fluid was only bleeding out of one and there was an airlock where the other hole was supposed to be. Took a small drill bit and opened up the clogged hole. Took about ten minutes and it was all bleed and had good handle pressure. It was a glorious moment. Feel silly for not figuring it out sooner.
 
Wow, haven't updated this thread in quite some time. Been enjoying riding it here and there. Need to get some more riding gear, have a jacket, gloves and helmet. But not really a fan of the jacket, looks like a Power Ranger suit. Haha.

A few updates on things, ended up tearing down the old engine. Found that the reason for the seized engine was a piece of the valve had broken off and fell into the combustion chamber. Chewed up the piston and cylinder walls pretty good.

Also put a new sealed beam unit and LED tailights on it and make a huge difference. However, I have been contemplating adding a 12" LED light bar to the front where the Yamaha logo is. But am unsure if the charging system will be able to support that.

72W of additional load would be asking a lot I think.
 
72W just for just a 12" light bar?
Seems excessive.

Which light bar is it?

Can save some power by switching all stock bulbs to LED.
Won't make up quite 72W but it would help.
 
Everyone on the road is going to HATE you if you run a light bar on the street. Headlights that are approved for street use have a cutoff for the beam so you don't blind everyone else on the road. A lightbar would basically like having your highbeams on all the time.
 
72W just for just a 12" light bar?
Seems excessive.

Which light bar is it?

Can save some power by switching all stock bulbs to LED.
Won't make up quite 72W but it would help.

Yeah, that the spec that's listed. Not sure how accurate that is, it is eBay after all.

Clicky Click

Everyone on the road is going to HATE you if you run a light bar on the street. Headlights that are approved for street use have a cutoff for the beam so you don't blind everyone else on the road. A lightbar would basically like having your highbeams on all the time.

Like I said, I was just contemplating it. I'm aware of cutoffs, I've retrofitted projector kits into car headlights before, believe me I don't want to be the jerk who puts a HID kit into reflector headlights...

The lightbar has reflector bowls for each LED, so the glare can't be that bad.


The new sealed beam I installed is magnitudes better than the original that was in there. I was just thinking about doing the lightbar for shits n giggles.

May just leave well enough alone.
 
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