Throttle Valve Shaft Seals

[AdvRich]

If one were to remove the C clip and the flat washer and then pack the area behind the flat washer with very heavy grease,  would one aquire a vacume proof seal in this area?  If so, reinstallation of the flat washer and the C clip might provide a viable alternative to seal replacment.

If this seems a viable method then by all means. It will save you $3 to $5 in parts.

Will you do the same for the other three seals as well?

[QBS]

AdvRich, from your pics and post it would appear that it's possible to remove the seal without disturbing the butterfly valve.  Is this so?

[pullshocks]

You guys are convincing me to do this "if" I ever need to pull the carbs again.  But I am going to practice on some old 82 carbs before I touch the butterfly screws in my precious 83's

[vintage bikeworks]

The screws retaining the throttle plates must be removed so the plates can be carefully extracted to allow the shaft to be pulled all the way out allowing seal replacement on both ends.  There is a certain amount of "finesse" involved in removing and installing each plate from it's respective bore.  Slow and easy is the name of the game here.  Because of the close tolerance fit, the plate may want to jam or cock in the bore. * DO NOT force or apply extreme pressure.  If it jams, reverse pressure to carefully free up and try again.  Properly aligned, the plate will slide through the throttle shaft cut out and the carb bore.  * Note the orientation of the plate after sliding out - There is a "top" and "bottom." Looking closely at the plate edge, you will notice it is chamfered in one direction to allow it to fit correctly when the linkage return spring brings the throttle plates closed.  Get it wrong and the butterfly plates will never fully close.

*important!!

[AdvRich]

You guys are convincing me to do this "if" I ever need to pull the carbs again.  But I am going to practice on some old 82 carbs before I touch the butterfly screws in my precious 83's

Great! Good you have a spare set to work with.

[AdvRich]

+1

The screws retaining the throttle plates must be removed so the plates can be carefully extracted to allow the shaft to be pulled all the way out allowing seal replacement on both ends.  There is a certain amount of "finesse" involved in removing and installing each plate from it's respective bore.  Slow and easy is the name of the game here.  Because of the close tolerance fit, the plate may want to jam or cock in the bore. * DO NOT force or apply extreme pressure.  If it jams, reverse pressure to carefully free up and try again.  Properly aligned, the plate will slide through the throttle shaft cut out and the carb bore.  * Note the orientation of the plate after sliding out - There is a "top" and "bottom." Looking closely at the plate edge, you will notice it is chamfered in one direction to allow it to fit correctly when the linkage return spring brings the throttle plates closed.  Get it wrong and the butterfly plates will never fully close.

*important!!

[AdvRich]

AdvRich, from your pics and post it would appear that it's possible to remove the seal without disturbing the butterfly valve.  Is this so?

Yes. I chose that easiest of seals to remove to provide a quick access for those that have not seen a throttle shaft seal, the well, shaft, etc up close.

Some pics for reference of the easiest of the four seals to access on the carbs.

The next easiest is the nutted one on the other carb.
The final two seals require the shafts to be removed as the throttle linkage plates are attached to the end of the throttle shafts. With carbs in hand it becomes very evident the level of work required for each seal to be accessed.

Hope this helps,
Rich 

[Re-Vision]

I practiced on an 82 and found that the screws removed more easily when I backed them out just enough to cause the peened end of the screw to begin to bend up slightly which occurs as the screw becomes harder to remove, re-tighten the screw and cut off the end. I used a pair of hobbyist side cutters and they came out easily.    BDC

[Rikugun]

Again, great information here.  :)

Rich, thanks for the additional info and pics and really good tip to try the carb spray/vacuum test at different throttle positions besides idle. Higher flow or just having the shaft loaded differently might reveal what would otherwise go undiscovered at idle.  :(

To add to vintage bikeworks tutorial... I've only done one set so can't say if this is typical but my throttle shafts wouldn't slide easily from the carb body. They'd move so far and stop. I found the area around the threaded holes was ever so slightly deformed and needed to be dressed in order to have them come out without gouging the carb body. I carefully went over the affected areas with a dremel until they slid out easily. I don't recall now if it was at the staked side or the screw head side but if some resistance is offered in extracting the shaft look at those areas carefully. ;)

QBS, personally I don't have much confidence in grease being a good solution but let us know how it works. You'd still need to remove the screws to get grease behind the plate on the one side. If you've gone that far you might as well put the proper seals in, yes?

[Night Vision]

I probably had leaking shaft seals... but compensated the lean surge at 5k rpm by increasing the main jet sizes...

the nice thing about these downdraft carbs is... if you're leaking a little air in.. just add a little more gas  ;)

[QBS]

Rik, I was trying to avoid what is apparently unavoidable, namely going through the stress of removing the staked butterfly screws.

[Rikugun]

I think this is one of those tasks that have been made into a huge ordeal but in reality it's not that bad. The notion of doing it is more intimidating than the actual work. Take it a step at a time, be slow, cautious and carefull and it will be ok.  ;)

[Rick G]

Sorry but to me , removing butterfly screws is night mare I experimented with it at work in 2002-2004  . The only way to get the screws out was to dremel the tips off , so they could be backed out . I could not come up with a way to support the shaft  and ended up bending s few, making them useless. Then I had  to find appropriate screws to replace then , as they are a one time shot. I tried O rings, but these caused the shaft not to return freely. i found on some carbs , like those on the XS650 , I could replace the one on the dead end of the shaft fairly easily.The other end was a different story.  Proceed with caution!

[Rikugun]

Sorry to hear you had so much trouble.  :(  Is there anyone else that found it difficult getting the screws out?  If so, any advice?

I didn't find the staking too bothersome so maybe it was the factory loctite? I know heat is recommended to loosen loctite so maybe one of those small "pen" butane torches would help? Plus it would add some fun drama if the fuel hadn't been completely drained!  :P

[Tiger]

After 30 years, they have to be replaced ... if you want your Vision to run right!!! There is no substitute for good maintenance...

                          8) ....... TIGER .......  8)

[Rick G]

as i said "proceed with caution"!

[munkyfistfight]

Ok, so while reading this thread I have two sets of '82 carbs sitting next to me in disassembled condition. I have managed to take all of the butterfly screws out (easily) ....BUT ONE!!! I went about it as carefully as I could but the philips head appears to be rounding out and I can't get a grip on it.

Bear in mind that the troublesome screw is in a set of carbs that came from a running bike that has relatively few problems. Should I proceed and find a way to get this screw out, or should I leave it and not bother? (maybe pack the seal with grease?)

The other carbs are getting new seals. The scews came out flawlessly, as did the shafts.

[vintage bikeworks]

Ok, so while reading this thread I have two sets of '82 carbs sitting next to me in disassembled condition. I have managed to take all of the butterfly screws out (easily) ....BUT ONE!!! I went about it as carefully as I could but the philips head appears to be rounding out and I can't get a grip on it.

Bear in mind that the troublesome screw is in a set of carbs that came from a running bike that has relatively few problems. Should I proceed and find a way to get this screw out, or should I leave it and not bother? (maybe pack the seal with grease?)

The other carbs are getting new seals. The scews came out flawlessly, as did the shafts.

Have you tried using Permatex valve grinding compound on the screw head to keep the screwdriver from slipping and/or rounding the head out?  (actually best used before the head starts to round out) This stuff should be available at any automotive parts store.  Permatex p/n: 34B

[Rikugun]

That's a good tip and I would also suggest heat to soften the factory thread locker. If the carbs are dry you can use a hobby sized torch available most hardware stores, Harbor Freight,  etc.  Another possibility is a soldering iron tip help on the screw. If that screw had been staked more aggressively than most you may need to get after it with a Dremel. Good luck and let us know how you make out.  :)

[Rick G]

One important facet of seal replacement is getting the  butterfly back in, so that it seats properly .