Butterfly Shaft Seal diagnosis

[Capt_Zoom]

OK, Can someone confirm my suspicion that my butterfly shaft seals have gone bad.

Symptoms
-bike only runs at higher idle
-light carbon fouling on the plugs.
-Getting 38mpg

So when using starter spray
-into the intake the bike dies (should it rev up?)(maybe I'm already running too rich?)
-onto the outer butterfly shaft seal area...bike dies
-onto the inner butterfly shaft seal area...nothing happens.
-around the carb boots and carb boot nipples....nothing happens.

To me this seems like I need new butterfly shaft seals.

Does anyone know if you can replace the outer one's without removing the shaft and butterflies?

Last...how long does this process usually take? I've read as little as 30min but I've never done it before. Hell if its only 30 min I might just have the dealer do it.

Thanks for any answers or suggestions.

 

[gggGary]

Leaky seals will cause a lean condition.

You pretty much have to separate the carbs and remove the shafts to get all the seals.
Depends on which carbs you have but;

I think the LH outer can be done on the bike even, but what's the sense in replacing just one of 4 seals?
Check shaft side play not in and out but up and down. If the shafts are loose even new seals will be a temporary fix. Don't see worn body/shaft here too often, but I think it's common on high mile bikes in dry sandy areas.

 

[TwoManyXS1Bs]

One more thing to check. On the 'suspect' seal, wiggle the throttle shaft, look for wallowed-out fit of throttle shaft to carb body throttle-shaft hole. If too loose, the seal may be a short term fix...

Haha, gggGary beat me to this, must be taking his vitamins...

 

[gggGary]

 

[jetmechmarty]

If you don't wish to do the job again three months after you did it the first time, OEM seals are available.

 

[Capt_Zoom]

Will definitely be buying OEM seals on Monday.

If its already lean should starter fluid cause an increase in RPM?

 

[5twins]

I don't think it matters if it's rich or lean, adding starter fluid is like giving it more gas so the RPMs should increase. If you have BS34 carbs, the outer seals can be replaced without removing the butterfly shafts and with the carbs on the bike. If you have '75 or older separate BS38s, the same applies. If you have '76-'79 linked BS38s, only the left seal on each carb can be changed without removing the butterfly shafts.

 

[Capt_Zoom]

1980 BS34 carbs. I can take the carbs off easily but after reading about the nightmares of getting those screws out and then peening the new ones i might just try to do the exterior ones. Probably order 6 anyway just in case I bugger a one up.

 

[jetmechmarty]

To remove the butterfly screws without boogering them up, you need a JIS screwdriver.

 

[5twins]

I use Motion Pro T-handles. They're not advertised as J.I.S. but they fit so well, I kinda think they are.

 

[duluthmuffler]

In addition to having a J.I.S. / Motion Pro T-handle screwdriver, are there any tricks to getting those screws out? Obviously trying to avoid boogering them... This season I want my carbs so clean they're like new.

 

[TwoManyXS1Bs]

This might help: http://www.xs650.com/forum/showthread.php?t=11980

 

[CDNTX650]

Grind the backs off with a dremel. Then they come out easier. That factory peening ruined one of my holes...had to retap to 6/32 and use loctite to make sure on all of mine.

 

[gggGary]

So far (about) 6 sets? I have not had issues backing the screw out without grinding the peens. But it could happen.... #1 thing I see with with guys boogering phillips head and I have watched and seen this.... Not enough downwards pressure on the screw driver. This is more important than using the JIS... (duck, firestorm coming) To do the shaft screws right; the carb has to be flat on a solid surface at just below waist height. You need to be extremely careful that the shaft doesn't "flip open" while doing this. An assistant would be very helpful. Now get a JIS screw driver and get your weight above the driver/ screw, lined up perfectly, pushing hard enough that if the screw doesn't move, you won't "cam" the screwdriver out buggering the slots. THEN start applying twisting pressure, wait for the "tink" of the threads "breaking loose" it will come, once you hear that, the rest of the trip is uneventful but keep solid downwards pressure on until the screw is turning freely this will be almost all the ways out because of the peens. Use lube on the back side of the screw before you start twisting, a dab of light grease would be good.
I cannot emphasize enough the correct posture position, your body will be above the screwdriver pushing down, with one hand applying a carefully increasing twist pressure. Here's an idea; try this procedure with a #3 Phillips on the "carb joiner" angle iron, those screws are VERY tight. Once you can do those without stripping a head, move on to the throttle shaft seals. Buggering up one of those screw heads is no big deal because it's easy to slot it or go to the hand impact wrench. You should NOT use a hand impact on the throttle shaft screws. The throttle shafts are thin, slotted and made of BRASS (chrome plated). Because they are brass it wouldn't take much to bend one, disaster!

 

[duluthmuffler]

Awesome! Thanks guys! This is all really great advice.

 

[gggGary]

PS BS38 screws tend to have more "peening", the BS34 screws are "easier to remove".

 

[xjwmx]

I'd dremel off the peening, just because it's going to be touchy enough already... a little help can't hurt. In my case and doing everything right I still stripped a head. It's soft metal, which is good. Use a left handed bit to drill down the center of the head and it'll come out. Actually I used a normal bit of a size that pretty much separated the head from the screw, and then caught in the screw and turned it out the back. Was actually pretty easy but found a replacement shaft to help determine my course of action with the original.

Interesting thing -- you should back up the shaft with wood or something, I've seen the fixtures on here, if you want to apply as much pressure as Gary is. But -- if you have that backing you should be able then to use the 1/4" hand impact then...so...