Carb slide question '81 XS

[cafe14]

A buddy gave me this bike 30-40 years ago and it has been a good friend. Very few issues, winterize it, start it up and go. That's what makes this bike so sweet, and me a terrible owner. If it wasn't broke I didn't fix it. Oil changes and very little maintenance since then.

When replacing a fuel line to the starboard-side carb I noticed that the slide on that carb did not go up or down when I twisted the throttle. It also didn't move when I engaged the choke. I heard a clicking noise, presumably from the other carb, when I twisted the throttle.

Is it possible I'm not getting full power from that side? I ran the bike about a month ago and it seemed to run just fine.

Can anyone explain what's going on? And how to fix it, if necessary?

thanks, Peter

 

[gggGary]

explain what's going on

the slide's not moving.

will it move if you lift it?

Is the choke fully off. (if the choke plunger isn't seated the slide won't rise)
Is the cap on the vacuum port? that cap is not cracked letting in air? ditto

 

[cafe14]

Thanks for the videos.

Somehow I thought the cables from the throttle on the handlebar activated the slides. I didn't realize air forced through the aperture above causes the slides to rise up.

It seems like I should just clean things up a bit and reinstall everything. And continue to praise Yamaha for producing such a reliable machine. It's actually a clone of my first bike, a '67 Bonneville. Yammy copied it and made it better, especially correcting the "Prince of Darkness" Lucas electrical system!

 

[gggGary]

To be completely clear; to do the port test the stream from the air gun goes ACROSS the port not into it. This sideways air flow causes reduced pressure above the diaphragm pulling the slide up. A holed or cracked rubber diaphragm can happen, bleeding away the vacuum, keeping the slide from rising.

 

[cafe14]

Good to know. I would have directed the air directly into the port.

 

[5twins]

Luckily, reasonably priced ($20) BS34 replacement slide/diaphragm assemblies are available from Cruzinimage.

 

[cafe14]

Thanks for that. I'm hoping I won't need them.

The reason I asked about the slides was that I was trying to replace a torn fuel line that feeds both carbs from the tank. It is a T-type fitting, leading to both carbs. It is very difficult to reach and I want to attach it firmly to the fitting so I won't have to do it again. I really don't want to remove a carb to do it- I don't want to make things worse.

 

[gggGary]

Thanks for that. I'm hoping I won't need them.

The reason I asked about the slides was that I was trying to replace a torn fuel line that feeds both carbs from the tank. It is a T-type fitting, leading to both carbs. It is very difficult to reach and I want to attach it firmly to the fitting so I won't have to do it again. I really don't want to remove a carb to do it- I don't want to make things worse.

Just the line or is the tee leaking?
https://www.mikesxs.net/yamaha-xs650-bs-34-brass-carb-fuel-line-t-piece-oem-3g1-14988-00-1.html
If it is the tee leaking, the carbs have to be removed from the angle iron front bracket to change or repair it. It's a fairly big project.

 

[cafe14]

No, thankfully the line just needs to be replaced. The tee appears to be fine. But the bottom extension is very short, maybe a half inch or so. It is difficult to stretch the tubing wide enough to slip onto the tee. I think it's one of those deals that it's a real PITA but eventually it can be done. Tomorrow, I hope.

 

[gggGary]

The tee rotates and should be pointed up. I'm in the no extra fuel filter in the fuel line camp, the ones in the petcock and behind the float needle valves are enough. Yeah it's a bit tough to get in there, part of the reason I like tygon fuel line, it's easier to work with.

 

[5twins]

If you use the proper and correct thin wall fuel line, it should go on pretty easily, and need no clamps other than the original style wire loop .....

It will also allow you to fit the protection/anti-kink spring. Automotive 1/4" fuel line is too fat and while it fits on the nipples, it won't allow the protection spring to be fitted. You can get nice thin wall line, just like the original, from YamahaXS650.com .....

https://yamahaxs650.com/product/black-rubber-fuel-line-1-4-x-25/

I'm on my 2nd roll, lol.

 

[cafe14]

Great pic, just what I needed to see that my tee is facing down, not up. Is that going to be a problem? Will it leak if I attempt to turn it 180 degrees? Should I just put the hose on as is?

There were no clamps on the original tubing. It just seemed tight enough without them. I don't think my friend, the original owner, did much of anything to that bike. Then he gave it to me and it's been super reliable.

 

[gggGary]

my tee is facing down, not up. Is that going to be a problem? Will it leak if I attempt to turn it 180 degrees?

Spray some lube at the carb/tee junctions. slowly twist back n forth a bit to free it up, then turn to the correct upwards orientation. Avoid "air bubble holding" downward loops in gravity fed fuel lines at all costs.
Hey @5twins quit messing with us! where in god's name did you dig up those oddball aluminum caps???

 

[5twins]

You can "scrounge" alloy tops for your BS34s from other Yamaha carbs (XS360, 400, and the XS750-850 triples), and also from Suzuki GS400/425/450 carbs.

 

[cafe14]

Rotating the tee after the lube wasn't bad. Tomorrow I should be able to put it all back together.

I couldn't have done this without your help. THANKS!

 

[5twins]

If the fuel "T" does start leaking on you, you can usually "fix" it by clamping the carbs together tighter. Loosen the mounting screws on the angle bracket and the top butterfly shaped plate, but leave them in place. Then tighten the clamp until the "T" is tight and barely able to be turned by hand, and finally, tighten those mounting screws back up you loosened while the clamp is still in place ......

 

[cafe14]

The job of replacing the fuel line has hit a snag. I went to the local small engine repair shop and bought some yellowish fuel line. My first attempt at fitting the line to the tee didn't go well and it it got mushed up. I cut off the messed up line about an inch or 2 . It looked like I had heated it up and the plastic melted. Except that I did NOT apply any heat to it. Pics included.

I then tried putting on the slightly shortened unharmed tubing on the tee and it looks like there is new "debris" inside the new section of tubing. So the big question is, is anyone familiar with the typical fuel line getting "debris" inside of it for no apparent reason? I really hate to complete the job to find that fuel will not go through it. And it seems like it would be potentially harmful to try to test it by running fuel through it.

All the pics of gunk stuff in the line were taken of the line I did not install. The tee pic, if you can enlarge it, shows some "gunk" in it. If you guys think that's OK I'll go with that.

Would the solution be to buy a role of fuel line that 5twins posted above? And toss the line I bought today?

Thanks for any and all help!

Peter

 

[5twins]

Well of course I'd say yes, lol. But I do a lot of carb work so that's why I got the 25' roll. You need 11.5" and they sell it in that length as well .....

https://yamahaxs650.com/product/black-rubber-fuel-line/

I'd buy at least 2 so I had a spare. Shipping won't increase until you get over $10 so theoretically, you could buy 6, lol.

 

[Dunc]

The job of replacing the fuel line has hit a snag. I went to the local small engine repair shop and bought some yellowish fuel line. My first attempt at fitting the line to the tee didn't go well and it it got mushed up. I cut off the messed up line about an inch or 2 . It looked like I had heated it up and the plastic melted. Except that I did NOT apply any heat to it. Pics included.

I then tried putting on the slightly shortened unharmed tubing on the tee and it looks like there is new "debris" inside the new section of tubing. So the big question is, is anyone familiar with the typical fuel line getting "debris" inside of it for no apparent reason? I really hate to complete the job to find that fuel will not go through it. And it seems like it would be potentially harmful to try to test it by running fuel through it.

All the pics of gunk stuff in the line were taken of the line I did not install. The tee pic, if you can enlarge it, shows some "gunk" in it. If you guys think that's OK I'll go with that.

Would the solution be to buy a role of fuel line that 5twins posted above? And toss the line I bought today?

Thanks for any and all help!

Peter

Must be ethanol resistant.

 

[cafe14]

Yes, at that price 2' makes sense.

I wish the parts guy had mentioned the possible ethanol issue. My state doesn't allow the sale of non-ethanol gas, but that bike has been using it without issues for a long time.

Thanks, guys.