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Mailman’s XS2 a full on restoration
- Thread starter Mailman
- Start date
Bob, just an FYI on the XS2/TX650 carb enrichment system.
Unique to the 72-73 carbs is the single choke in the left carb, which has a crossover tube to feed the right carb. As such, the choke fuel pickup tube is in the left carb only. Using your carb pic, here's the choke fuel routing.
Fuel is drawn up thru the pickup tube, and intermixed with air at the front on the carb.
1- That air/fuel mix emerges to the bottom of the choke plunger.
2- When the plunger is raised, it's mixed with more air and delivered to the "C"-shaped channel. This zone is shared to the other carb.
3- Where it emerges into the carb throat.
The "C"-shaped channel will always be at a vacuum. Which includes its port/passage astride the choke plunger. Ensure that the plunger gasket seals between points 1 and 2...
Unique to the 72-73 carbs is the single choke in the left carb, which has a crossover tube to feed the right carb. As such, the choke fuel pickup tube is in the left carb only. Using your carb pic, here's the choke fuel routing.
Fuel is drawn up thru the pickup tube, and intermixed with air at the front on the carb.
1- That air/fuel mix emerges to the bottom of the choke plunger.
2- When the plunger is raised, it's mixed with more air and delivered to the "C"-shaped channel. This zone is shared to the other carb.
3- Where it emerges into the carb throat.
The "C"-shaped channel will always be at a vacuum. Which includes its port/passage astride the choke plunger. Ensure that the plunger gasket seals between points 1 and 2...
Float seat can be tested with bowl off and hook up fuel(with cup underneath carb to catch fuel)...
Manually hold float up and no gas into cup, let it drop some and flow...
...and on the needle valve the tiny springed tip at opposite end of seal must work...push it in and see it return freely...
...kind of starting point to see where you at maybe...
Manually hold float up and no gas into cup, let it drop some and flow...
...and on the needle valve the tiny springed tip at opposite end of seal must work...push it in and see it return freely...
...kind of starting point to see where you at maybe...
Thanks Steve, I was trying to wrap my head around this , I appreciate the explanation. I might need to order me a couple new gaskets to replace some homemade ones I did out of some rather thin gasket paper. I will check all that out. Thanks again.
That’s an interesting idea testing the float needles with the bowels off. I might just try that, thanks!
Just catching up on this - dang it Bob.
Well, lots of good ideas here. You’ll get there.
Pete
Well, lots of good ideas here. You’ll get there.
Pete
What year did the float needle valve length change?
pamcopete
Ride.Enjoy.Life is Simple
I think there is a slight misconception here about shutting off the pet cocks. If you leave the pet cocks on, then the more aromatic components of the gasoline will evaporate from the carbs which does two things. The word "aromatic" tells us what the first thing is, but the evaporation also causes the floats to go down just enough to let in more gas and replenish the aromatics to add to that distinctive gasoline smell in a closed area like your garage. I always shut off the pet cocks in the four bikes in my garage and if I forget, I can instantly tell in the morning as the whole garage smells like gasoline, but there is no evidence of fuel on the floor.
Lunch at Chipotle time ? 
Really ! The aluminum trays avaliable there are just the right size and shape to bend just a little and use as a carb drip tray !
I use them while draining carb bowls into or when testing petcocks too. It will collect any suspect debris and you wont spill a drop again
-Randy
Really ! The aluminum trays avaliable there are just the right size and shape to bend just a little and use as a carb drip tray !
I use them while draining carb bowls into or when testing petcocks too. It will collect any suspect debris and you wont spill a drop again
-Randy
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Well, from the hour it presently is in Phoenix, I can clearly see that Mailman is up and at ‘em and determined to get this danged fuellish problem solved and done like dinner!
All I can say is ....GOOD!
All I can say is ....GOOD!
And we all have Mailmans Motorcycle channel on at work !
looking at the petcock pics, yours, (both new and old), and Jim's, the factory casting looks to quite good and the new one looks shit. Would it be to much hassle to take off the tubes and do a flat surface rub. This will make the Rubber seal protrude a bit more and also make sure the petcock base is level and remove those imperfections..........just a thought and now your OCD is going to kick in
Another thought on test running with a suspect carb overfill condition.
In my own case I test ran my XS in the driveway which has a slight tilt. With the front end up just a tad I think this leveled the carbs just enough so that when my own rt.side carb overflowed due to debris in the needle seat, the fuel flowed right out the air box.
No detection of fuel in the oil yet. Though an oil change is immenent anyway.
This may help you to have the float bowls more level than on the garage floor with the rear wheel up in the air ?
In my own case I test ran my XS in the driveway which has a slight tilt. With the front end up just a tad I think this leveled the carbs just enough so that when my own rt.side carb overflowed due to debris in the needle seat, the fuel flowed right out the air box.
No detection of fuel in the oil yet. Though an oil change is immenent anyway.
This may help you to have the float bowls more level than on the garage floor with the rear wheel up in the air ?
+1 on the clear tube method. You inadvertently proved the carbs are overflowing. The needle and seat should and I stress the word should stop all fuel flow. But they are not fail-safe.
Go to robinc's thread and read #388.
http://www.xs650.com/threads/on-the-road-again-at-40-the-bike-that-is.49360/page-20#post-521873
You may have more than 1 problem, float level is the place to start.
How are you going to be able to fix the paint on you cases. I almost cried when I saw the pic of the fuel damage to the paint.
Go to robinc's thread and read #388.
http://www.xs650.com/threads/on-the-road-again-at-40-the-bike-that-is.49360/page-20#post-521873
You may have more than 1 problem, float level is the place to start.
How are you going to be able to fix the paint on you cases. I almost cried when I saw the pic of the fuel damage to the paint.
+1 on the clear tube method. You inadvertently proved the carbs are overflowing. The needle and seat should and I stress the word should stop all fuel flow. But they are not fail-safe.
Go to robinc's thread and read #388.
http://www.xs650.com/threads/on-the-road-again-at-40-the-bike-that-is.49360/page-20#post-521873
You may have more than 1 problem, float level is the place to start.
How are you going to be able to fix the paint on you cases. I almost cried when I saw the pic of the fuel damage to the paint.
I remember Robins set up very well. He really rigged up a nice testing station.
Re: the paint, I haven’t given it more than a cursory examination yet, but it almost looks like it just affected the clear coat. I might be able to scuff the clear off in that area and mask everything and respray. I think I can touch it up in place. Especially since the carbs and airboxes are out.
....you must be getting awfully good at R&R-ing those carbs and airboxes Mailman....
From the moment I walk out in the garage, to the moment their lying on the bench. 15 minutes, and that includes a coffee break!
Always hard to decide if I'm 
proud
or 
ashamed
of how fast I can pull a set of carbs.......
practice, practice, practice.
As mentioned above madness was leaking out an overflow, gave her the old ride the be-itch cure, bingo!
proud or ashamed of how fast I can pull a set of carbs.......practice, practice, practice.
As mentioned above madness was leaking out an overflow, gave her the old ride the be-itch cure, bingo!
