Petcock question.

Joseph Michael Napper

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I'm cleaning out my fuel tank with some metal rescue. The petcock has three settings- on, prime, reserve. Where's off? It's a sohc 1980 xs400 special. Thanks everyone.
 
I always remove the petcock when putting anything other than fuel in to be safe. That said, 'ON' will be off as long as the bike isn't running. It needs the vacuum from the engine to open. 'PRIME' however will let the fuel flow openly.
 
Yes, thanks. Petcock and tank are all good. Gotta take the carbs off now, getting fuel coming back through the intake. Probably stuck floats and clogged jets. Any advice is appreciated.
 
Stuck floats likely. I had to give slight bend in my needle as it was rotating off of the tang of the floats. Can test it when you have bowl off by rotating carb body and seeing if it freely closes or hangs up when trying to shut. Took me a while to figure out slight bending the needles small hanging mechanism fixed it
 
Thanks. Just got it back together, ran rough for about 20 seconds, got gas leaks at the exhaust pipe by the kickstand. Think I'm out of my league. May take carbs in to a pro. Know how much that runs? Thanks again.
 
Taking anything to a mechanic will be pricey and they probably wont do it, aside from builders and tuner shops.

What did you do with the carbs when you had them off? Did you replace any parts? How many times did you clean the carbs?

We need more info about what youre doing. The worst thing to do with anything mechanical is to just start taking stuff apart, unless you really know what youre doing. Having a paperback shop manual is essential IMO.
 
Sure. Kept it simple. Removed floats, needles and jets, soaked in cleaner and gently scrubbed them clean. The jets and needles were clogged and everything else was very dirty. It ran rough like I said so I'm thinking the carbs just need a better cleaning. I don't have an air compressor.
 
Buy compressed air aerosol can, does enough for this
Floats to 26mm from below gasket seat?
Did you watch the videos on forum? They are a big help.

Explain gas leak more, if comes from Air box then it is probably still float related. As I said I diagnosed this sticking needle by rotating whole carb body
 
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Initially it was leaking from airbox, before I cleaned carbs. After, itran rough and gas was coming out of a small hole in the exhaust where the muffler meats the header right by the kickstand. Also, I was looking at Mikes xs preformance carbs for xs400 on that site. $359 ain't cheap but it would get me into a pretty sweet bike for $1100 dollars spent total. Have you heard reviews on them? Thanks.
 
If youve never cleaned the carbs before, its best to do it about 5 times lol.

I use an ultrasonic cleaner and various soaps and my carbs come out looking brand new.
 
IMG_20190421_090042.jpg
 
Others can reply with better info, but don't those come tuned for pod filters? You'll still have to do some adjusting and balancing, but it's your bike to do with as you please.

Did you check compression?

Are you sure it is gas coming out of your exhaust? I would guess it is either leaking elsewhere and dropping down onto exhaust and tricking you. Sure it's gas?
 
I'm pretty sure it was spewing out out a small hole in exhaust, felt it with my hand. I re-cleaned float needle and seats and it stopped doing that. Now the petcock has given up the ghost, leaking. Easy fix, gasket. Thanks.
 
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