Seca 550 fuel petcock question

Just starting total rehab of my 82 seca 550... Which has been sitting for 5 years has 8500 miles on it.
Now it's time to get the tank of and clean and seal. I have question about the fuel peacock....Down is on....front is reserve for when gas gets low right?...Not sure what "PRI" means in the rear position I assume it means to prime?
I was turning the valve back and forth to get it loosened up and I turned it back to "PRI".....then gas started pouring out of what looks like an overflow tube going down in front of rear wheel?...so I turned back the other way and it stopped....anybody have experience with this?..does this indicate a malfunction?

 

Yep PRI is prime & the gas is likely coming from overflowing carbs flooding into your airbox & into your oil too, see Church of clean & The whole 9 yards for info on repairing/cleaning your carbs.

At least the fact that it stopped indicates that your petcock is working

Welcome to the forums, I'll link those thread in a moment so you got some reading material

EDIT-; Here we are http://xjbikes.com/Forums/viewtopic/t=14692.html

 

Here's another, I can't find "9 yards" but will keep trying!

http://xjbikes.com/Forums/viewtopic/t=14751.html

EDIT-: Here's 9 yards too 8) Enjoy, any questions read up, search & then if you're still stuck just ask, we're here to help

http://xjbikes.com/Forums/viewtopic/t=2 ... yards.html

 

On a vacuum operated petcock like those on XJs, the PRI position is useful to fill up the carb bowls before you attempt to start the bike, after long storage for example.

But you don't need to leave it on PRI for more than 30 seconds. Put it back to ON or RES if you're low on fuel.

 

If gas poured all over the place with the petcock in PRI then you have one or more stuck floats; and very well could be polluting your oil with gas in the process.

Pull the carbs and do the basic service as outlined in both the factory and Clymer books, plus pop the pilots out too. With that few miles, you may be OK on throttle shaft seals as long as you don't submerge the carbs and kill them.

Then get the valves in spec (IMPORTANT) and the floats properly adjusted before you try to sync or tune.

GET A BOOK if you don't have one. You're gonna need it.

 

Thanks guys...all good info...I have been collecting and reading carb cleaning tips for a while prepping for the big tear down...turns out the first one I saved was Rick Massey's 9 yards...which I like a lot.
Seems like "9 yards" method keeps the carbs together during the process...I'm a little skweamish about messing up synchronization so would like to avoid separation. Can I do a good rebuild without separating?
I see cracking around the exterior of rubber boots that go from carbs to the head...are they doomed? Or is interior usually still intact?

 

You could clean "on the rack" but you'll find it much, much easier IMO to split them, and you'll be syncing them whether or not you do split them so that's no reason to be put off doing so

You don't, as Fitz already pointed out, Have to remove the butterfly shafts/seals (unless they're obviously knackered, and if the carb boots are iffy I'd suggest the rubber components have maybe had a fair share of UV/ozone exposure)

The rubbers to the head could be OK but I'll leave it to others to advise further on that as It's not advised to touch the cap screws if you can help it, and I'm in the UK & rubber is less affected here,

FWIW I'd say probably still intact. And do bear in mind what Fitz also said about soaking carbs, make sure ALL rubber parts are removed (including diaphragms/pistons and pilot screw o-ring/washer/springs) before soaking the bodies, or it either turns to mush or goes hard & brittle.

 

Let's clear up a couple of things.

First off, you don't submerge carbs unless you plan to pull the throttle shafts and butterflies to replace the throttle shaft seals. It's not a matter of getting everything else out first; you only do it with a complete teardown.

Forget "messing up the sync." That's going to happen as soon as you put the valves in spec and work on the carbs. You DO NOT have to break the rack for the basic carb service procedure. Get a manual. Both the Clymer and factory books cover the process very well, except they deny the existence of the pilot screws (capped from the factory.)

Once you've cleaned and serviced the carbs and adjusted their floats, you do as accurate of a bench sync as possible.

Then once back on the bike, you do your running vacuum sync.

It's not difficult, per se; but it requires careful, thorough, precise work. The small-bore 550 motor is seemingly more sensitive to carb adjustment than the bigger bikes, and the Mikunis a tad more involved.

Here's a Mikuni being torn apart for service (throttle assembly still in place) http://xjbikes.com/Forums/viewtopic/t=31061.html

As for the intake manifolds, once the carbs are off, flex them from inside with a fingertip. You'll be able to gauge the depth and severity of the cracks. Quite often, they're fine, and you can pack the fissures with black adhesive RTV.

 

Thanks I'll follow your direction and forge ahead....