dragonnoodle

Be careful with the mixture needles the tips like to stay in the carb body if toightened too far and if left tighten for too long. your kick start shouldn't bind up on the brake peddle at all, maybe rub but not bind.

When you say relay do mean the ignition itself or the connectors? Drewpy you just added a wire from the ignition to your head light switch? Did you have any issues with that?

I was told the bike was a 79 so I was looking at those wireing diagrams, Haynes, and most of the wires didn't match so I checked the 78, since a 79 xs400 doesn't exist on some part site, almost everything matched the '78 diagram. Low and behold everything matched until I got to the ignition switch 78 4 wires 79 3 wires I got three on both sides of the junction plug not spliced or anything. My question all my lights work; turn signal front and back, brake light running and front and back brake switchs 12volts. Head light ~.5 volts and gauge lights ~.5 volts. How does the bike run and all the electrics work with full power and the head light and gauge lights only get .5 volts. I can understand no power but just a little bit of power.. I'm stumped. Thanks for all the help, Scott

Try Mikesxs.com Oldbikebarn.com 650central.com and try omars I don't remember the site but just do a google search.

Does it happen no matter what gear you are in? Whats you throtle position and what RPM are you at. You might need new coils or condenser. If you're tuning it you might as well get them for added peace of mind they're fairly cheap. go to MikesXS.com. A lot of parts for the xs650 will work with the 400. I checked the part numbers for the coils and they are the same between the two bikes. And if you're running point make sure to get non resistance or 1ohm resistance plug caps, you need as much spark as you can get with points.

Those bikes are gorgeous! Nice Job.

What carbs are everyone running? Stock? Mikuni? Klien? Round slide? Flat? CV? Size?...... I'm asking because I need to get new carbs because my stock ones are unrepairable. I emailed Mike at 650 central and he thought Mikuni VM34's were too big but the bike came With 34mm carbs stock. And I have no idea what all the numbers and letters for jets mean So I have know idea what initial setup to put the carbs when I order them. Any suggestions. Any help. Thanks, Lost

Thanks that helps a lot and will save me a couple hundered bucks for new carbs. It seems as though everyone uses the Mikuni VM34 carbs, but no one knows a base line jetting setup. Wouldn't you start with the same setup as your stock carbs. I ony ask because I figure I'll get them at some point when I have the means. Hell I just want to get the damn thing to run at this point.

The carbs from the '80 and up xs650s are Mikuni BS34mm CV carbs and they are jetted the same as the xs400 carbs, at least from what I've seen. Go to a yamaha oem parts site and look up the carbs for your bike and the carbs from the bike youare getting and compare the specs just to make sure. The xs400 had three or four variations on the mikuni BS34mm CV carbs.

I was pulling the carbs apart for a good cleaning and found who ever had the bike before me tightened the idle mixture screws too tight. The tips twisted off and are stuck in the carbs and they won't just push out, they've been there a while. Is this repairable? If I have to replace them what carb would I use, since the mikuni bs34's arn't made anymore? Thanks S.