Carburetor Butterfly Seals - Throttle Plate Shaft Seals

[Cdnlouie]

This may have been noted before but while I am here I will add something on the butterfly seals used on our Vision carbs.

I have checked a few badly weathered carbs recently and noticed that the butterfly seals are not in very good shape.  As I was looking for where I might obtain some seals I spoke to Keyster (Kitchener, Ontario) who made up our Vision sets and they listed these seals as available with one of their dealers http://www.motorcyclecarbs.com/

They are 6.00 a piece which is not cheap (two per carb), but they are available and would be nice to have done in a newly cleaned set of Vision carbs.  Of course there are considerations for the average person to do this, that Lucky has pointed out previously.  Removal of the throttle plate screws is often difficult and alignment issues after the fact can be serious considerations.  Unless you have some spare parts and are very, very. careful this may not be a good idea for you  :-[.

Good health to you and your Vision,

Louie

[Lucky]

got part numbers? gonna need some to resurect a few 83 carbs

[Cdnlouie]

Part No. 5598 fits all butterfly shafts of 8mm with housing I.D. of 11.5mm.

I was wondering if we could get a bit of a deal on a few.  In talking to Martin at Keyster he mentioned that Robert at www.motorcyclecarbs.com  (who is one of Martin's Keyster dealers) is stocking them and he just orders what he needs from him.  They are 6.00 US a piece.  Shipping unfortunately increases the price substantially.  It gives us a contact anyway.

Louie  :)

Motorcyclecarbs.com, Inc.
4292 Country Garden Walk NW.
Kennesaw, Ga. 30152 USA.
Office: 770-974-8851
Fax: 770-974-8852

[Cdnlouie]

The O, square and x seals are not used on the throttle shafts.  The butterfly seals are a special design they may be called "cup seals" as they work to seal against low pressure applications.  Believe me, you do not want a throttle shaft to jam on you, o-rings and the like are typically used in static applications where sealing is the only requirement.

[Night Vision]

I looked on Mike's xs650 site.
seals there were also $5 each, so it's not like motorcyclecarbs.com is out of line.

[Cdnlouie]

I ordered 8 of these seals to refresh a set of 82 carbs that I am restoring to original condition with all the gaskets, seals, etc, etc.  I will have four in reserve for anyone nearby who wants to do the throttle shaft upgrade.  You can get to turn back the odometer for another 25 years on your carbs.  ;)

[Cdnlouie]

Hmmm.... :-\

I pulled apart another carb set today and these butterfly seals are really toast.  There is no longer a tight seal around the throttle plate shaft.  I am not sure how much difference this is making in performance for most Visions, but it definitely is an issue to be addressed going forward.  These seals have shrunk from age and they are working more like a rubber washer than a seal.  We are going to have to replace these things if we want a really nice working carburetor.  The days of the cheap carb cleanings are over. It's going to be $30 for seals (including shipping) and then the precarious work of installing them (no small task). But then again, once all the rubber stuff is replaced they will be good for another 25 years.

Good carbs are the answer to keeping these Visions alive, so something to think about.

Happy 25th Birthday Vision owners,

Louie  8)

[Cdnlouie]

Installation Techniques...

So far there is a real risk to getting the screws out of the throttle plate.  Soak them well in some penetrating fluid. I have not looked for replacements yet, but that is an issue to be addressed as well. The throttle plate is very soft metal so it needs to be pushed out delicately with a soft rubber screwdriver end or the equivalent, down the throttle body and out the bottom.

The seal installs with the "U" side (open face) facing out. I would put a bit of silicone grease on the shaft to lubricate things.  There is a plastic washer on one side to protect the seal and then on the other side (spring side) there is a nylon bushing (on the rear carb, flat washer on front) to go on the shaft, then the spring, throttle stop plate, lock washer and nut.

Make sure you install the throttle plate with the number down (looking at the number from the bottom of the carb) as the throttle plate is beveled so it can turn in the throttle body without jamming.

I am going to go with loctite (red) for the plate screws and trust in the reputation of the company thereafter. I might wake up at nights wondering if I used loctite on all the screws in my carburetor, but hey if you're not dreaming about something, your dead.  I 'll go with the former.

If you are real careful you might be able to peen the end of the screw, but that would require being real careful! There is a lot you can damage if you miss the screw, I will leave the rest up to your imagination.

Well that was fun,

Louie  ;)

[Lucky]

I'd also add the for the most part the original screws were staked in & can & have broken upon removal.  be Very careful!!.

Also, if you do not get the butterflies installed correctly, they can bind & stick open at FULL THROTTLE.  not a good situation.

--Lucky

[Brian Moffet]

Also, if you do not get the butterflies installed correctly, they can bind & stick open at FULL THROTTLE.  not a good situation.

And should this happen, hit the kill switch and the clutch.

(been there, done that, not on the vision)

Brian

[h2olawyer]

Not thinking about the possibilities & not having this forum available the first time I thoroughly cleaned the carbs, I took the butterflies out of mine.  I have checked them every time I've cleaned them since, & they remain tight.  I used red loctite when I reassembled them & that was over 10 years ago.  The ones in my carbs weren't difficult to remove.  Didn't even feel like they were peened, staked or otherwise sealed.  Very minor 'click' as they broke loose.  Dealer may have done something with them before I bought the bike.  Otherwise, I know the whole history of the bike - they have been removed only one time since it had 6 miles on it the day I bought it.

Still, it is best just to leave them alone unless you are replacing the butterfly seals.

H₂O

[Cdnlouie]

Just bumping this topic up again in case anyone is interested  8).

[George R. Young]

I had that problem and replaced them with little o-rings.

[Hartless]

next time someone has their carbs off, would they be kind enough to ts
ake pictures of the location of these seals. carbs are def my downfall when it comes to working on bikes

[Cdnlouie]

Hartless, email me and I will send you a picture.

Howdy George...good to see you're still lurking out there. The o-rings may indeed work but it's probably not worth the risk of getting the wrong size and potential throttle shaft binding. I'm sure you know what you're doing and could mitigate the risk, but not a good idea for someone without a bit of mechanical background.  The butterfly seals are available now and a safer option.

[TheRadBaron]

I was looking at these shaft seals on www.motorcyclecarbs.com.  I found the #5598 for $5 each, not $6 as stated above.  I also noticed that there were available some genuine Mikuni "double sided" shaft seals (#10904) that are described as sealing better than other designs, and they can be used in place of the 5598 seals.  They're $6 each.  If they offer better sealing, I think that I might give these a shot.  Does anyone have any insight on these? 

[Tiger]

I found the #5598 for $5 each, not $6 as stated above. 

Do not forget that CANADIANLOU would have to take in to account whatever exchange rate was available at the time...besides what difference does a dollar make between friends ;)

            8) .......TIGER....... 8)

[TheRadBaron]

Oh yeah.  I guess that I knew that Cdnlouie was Canadian.  I didn't take that into account.  I just thought  that maybe motorcyclecarbs had lowered their prices or similiar.  Sometimes tone comes across wrong when typing.

[Cdnlouie]

On the new type butterfly seal I am hesitant to try something different than the original. It may be a better seal, but the original did the job for 25 years so I have stuck with the original design. It looks like it seals differently so it made me a bit uneasy about trying it. I think someone should try it so I will leave that up to the pioneers. If I could see one up close and personal I might change my mind on the issue.

The orginal's have a pretty good sealing capability as the "wings" on the seal are quite wide to trap the vacuum.  The new one looks to have a narrower sealing edge but it has two and that may do the same.  However the ridge on the inside I am having trouble seeing how it seals, as it is positioned in the opposite direction from the vacuum, seeing it up close might change my impression, but that's what I can see from the picture.

Bottom line I stick with what I know works unless I'm feeling adventurous  ;).

[QBS]

At approx 88k miles, the butterflys on my '83 have never been removed or molested in any way.  How would I know if their seals have or are failing?  What are the symptoms of failed butterfly seals?