tstidham

Well, you do want the petcock to be able to shut off. My original vacuum petcock also went bad, but to be expected for 40+ year old...

Unfortunately no. The floats and seats should hold enough of a seal to not flood even with the petcock open. I ditched my vacuum petcock...

Float levels or needles and seats are leaking. Check your oil level too, if it increased, then the fuel also leaked into the crankcase...

The fuel leak could also be from bad needle and seats in the carbs. I had this issue as well, especially when on the side stand with...

Turn the petcock to pri for prime. This bypasses the vacuum valve to fill the carbs. Also I'll say check the kill switch is on. On my...

Yea nothing special, what avemachina said.

It looks like you're missing the top throttle cable housing bracket. It holds the end of the cable sheath so just the inner cable moves...

Not necessarily, I have seen batteries that failed in such a way as to pull so much charge voltage that it overwhelms what the...

I'd say the battery has a bad cell if it's dropping to 7 volts in 30 seconds. When I first got my 78, I didn't realize the voltage...

How many rpms is it idling at? I can't speak for the xs250, but the xs400 idles at 1200 rpm. I'd imagine the 250 is similar.

That's how the mixture screws look on my 78. Makes tweaking them pretty easy!

When I first got my 78 running, I had cleaned the carbs three times, but in the last time I used a single strand of multistrand 10 or 12...

The underside drain plug is in the middle of a rounded rectangle plate with something like 6 or 8 bolts holding it on. Remove those and...