Throttle Valve Shaft Seals

[pinholenz]

I haven't dismantled the butterfly valve in the carbs or removed the shaft when I have done my strip and cleans.

However I do notice an engine idle change when I spray carb cleaner on to the throttle valve shafts, suggesting that I have leaking shaft seals.

I can't find these seals listed in the carb parts list at
http://www.yamaha-motor.com/partviewer/default.aspx?ls=sport#/Yamaha/XZ550RJ_-_1982/CARBURETOR/XZ550RJ_%281982_MOTORCYCLE%29/CARBURETOR_%28XZ550RJ_-_1982%29

Can anyone give me a parts number or suggest what to use to replace the seals?. Many thanks

[George R. Young]

I used little O-rings.

[Cdnlouie]

Check out the info posted here:  http://ridersofvision.net/rovforum/index.php?topic=6017.msg117298#msg117298

[Rick G]

Yamaha never listed them . Their solution to leaking shaft seals is to buy new carbs!  Ya sure

Changing shaft seals is  not an easy project , The butterfly's are held in with tiny screws  that are staked. staking new screws is a perilous operation , as it very possable to bend the butterfly shaft,

[QBS]

Have not done this.  What about soaking the part of the carb body that the butterfly seals reside in with some type of solvent known to cause swelling in rubber?  Same concept as auto transmission and power steering stop leak products.  If imersing the whole carb body would cause problems for other rubber componets, perhaps a way of isolating and soaking just the butterfly seals could be contrived.

Really glad to see this discussion of leaky butterfly seals come up.  It's a problem that all our carbs either are facing, or will soon face.  High miles and old rubber are a double whammy.

[Rick G]

I dip carbs in carb cleaner, for no more than 30 min.  This softens the seal a bit and cleans the carb, My policy is to NOT leave the carbs in the dip any longer , as the seals can be destroyed.

[pinholenz]

Thanks for the link to the 2007 discussion thread Cdnlouie, that was exactly what I needed. Not a job for thew faint hearted.
I like the notion of re-juvenating the existing seals whilst they are in place. Any suggestions for product that we might spray on while the engine is running so that the product is drawn in to the leaking area to 'swell" the rubber?

[Cdnlouie]

It is a great idea to replace these seals as they have all reached retirement age by now.  Some are still actually okay (I have an old set that are still good) if they have been in machines with regular use, but long term storage causes the rubber to lose some of it's elasticity.  These shaft seals have a very delicate outer edge that needs to flex in order to seal.  They are like the sails on a boat and when they harden they can longer catch the wind (vacuum more precisely) and press against the carb body to seal.  Regular immersion in gasoline actually preserves the rubber elasticity (apart from the downside influence now of ethanol), and once they shrink there is no coming back.  However, I  do know that varsol does causes rubber to swell (left a few o-ring pieces in too long during cleaning in the past).  I have never experimented with it on a shaft seal, nor would I recommend the process, but you asked  ;D.

[jasonm.]

FYI- Many carb dips will eat the rubber quickly. I believe there is a YAMAHA carb dip that is rubber safe. But most are not. Don't think even 30 minutes is safe. As a test I watched rubber o-ring desolve to uselessness in far less than 30 min.

[fret not]

Way back when I worked in a parts department I saw some monstrous things that the current carb dip did to various "rubber" parts.  The little gray cylindrical plugs that fitted between the cylinder fins to keep them from ringing would swell up to the size of a golf ball, some O rings would also swell to gigantic proportions. "Fortunately" we are now safer here in California, as the currently available carb dip is about as useful as dirty dishwater. 

[Rikugun]

I think that's the case across the board. All the carb dip products are much kinder/safer i.e. less effective. The Yamaha dip is literally "watered" down.  :o  It's sold in a concentrate that you must mix 2-1 water to product to make the final solution. I think the instructions indicate an hour dip but don't hold me to that. I used it in an ultrasonic cleaner for longer than that and everything seemed to be OK afterwards!

[Rick G]

It depend on how crusty they are  . I usually dip them for as little as 10/15 min.  If there really bad I go up to Dream machines and use their glass beader. . Then I ahve to run them through the dish washer , twice ,to insure that there  is no grit left.

[Rikugun]

Rick, I'm guessing the stuff you use is what you may have found in a repair shop back in the day? Even if that's quite old and lost some effectiveness I'll bet it still works better thane the Yamaha dip. Fifteen minutes in the Yammy brand would do very little. I dare say one would get equal results by resting the carbs on a bench and talking harshly to them for a bit. A sound scolding indeed!  :D  :P  :laugh:

[Rick G]

Rik, well sort of . I bought a 2 gallon can in WA. in 2003 , It was labeled "Not for sale in the state of CA,"  so i knew it would be good . I've been topping it off with the same brand (Berrymans)  here in AZ.  A couple of years ago the can started leaking , so I bought a porcelain stew pot and dumped everything it that . Its a bit taller and wider , which I like .

We ordered a couple of cans of carb spray and what we got was some kind of thin red oil, that did nothing. Turns out it was sent by mistake , it was intended for CA.  I'm glad I left there in '96!

[AdvRich]

I haven't dismantled the butterfly valve in the carbs or removed the shaft when I have done my strip and cleans.

However I do notice an engine idle change when I spray carb cleaner on to the throttle valve shafts, suggesting that I have leaking shaft seals.

I can't find these seals listed in the carb parts list at
http://www.yamaha-motor.com/partviewer/default.aspx?ls=sport#/Yamaha/XZ550RJ_-_1982/CARBURETOR/XZ550RJ_%281982_MOTORCYCLE%29/CARBURETOR_%28XZ550RJ_-_1982%29

Can anyone give me a parts number or suggest what to use to replace the seals?. Many thanks

Hi pinholenz,

Throttle shaft seals on bikes this old should be replaced IMHO and anything short is just delaying performance and trouble free operation for years to come. You get one good shot for each screw so prep and diligence is key. An application of PB blaster or the like will help if the screws don't initially turn out easily, but clean the philips part with brake cleaner before you apply the screwdriver. Its all in the feel and even a slight tightening torque is what's needed to break them loose before unthreading. Also, a new or in top condition well fitting #1 phillips, attention to applied pressure so as to not bend the shaft or strip the heads, and attention to the staked part coming though the shafts threaded section (turn back in if needed to clear the threads and reduce jamming) is all part of the mix in negotiating the change out crux successfully. I've not had any trouble with the screws to date, but I also had carbs that were not in poor condition with lots of corrosion and such.

For my most recent replacement on a set of TDM carbs, I found a sweet set of metric counter sunk stainless allen screws at my local Ace. They're a perfect fit and a dab of loctite will set them well. Also be sure to put the seals in in the correct direction (V opening to the outside) so they seal with vacuum.

You'll need four of these 256-14997-00 (throttle shaft seals) direct from Yamaha. They fit many carbs on many makes... I forget the exact size at the moment.. 8 x 11.5 or something. They are listed on the old Yamaha XS650 twin fiche page. They're also cheaper in cost then the ones from aftermarket. 

Cheers,
Rich

[vintage bikeworks]

I'm in full agreement with AdvRich.  Why go to all the trouble of carb disassembly, soaking, cleaning and reassembly without replacing the throttle shaft seals?!  ???  I've rebuilt several Vision carbs and always replaced the seals.  Not a big deal at all.  Some noteworthy advice - Use a #1 phillips for correct fit during removal/install.  btw...  The screws are actually "oval head" phillips and not a traditional countersunk.  Screws can be purchased from McMaster Carr under p/n: 90258A178, are M3 thread, 8mm long and stainless to boot!  Be sure to use a thread locker such as loctite #222 (designed for small screws and removable if needed) when installing the new screws.  Correct seals are easily obtainable from motorcyclecarbs.com by ordering p/n: 5599 @ $5.00 each.  The seal has an angled lip design and you must be careful to install in the correct direction.  Remember, you are dealing with vacumn and so the seals should be installed with the lip facing outward, away from the carb - Opposite from what you might think when installing a seal on an engine shaft or front fork tube.  The reward for replacing the butterfly shaft seals will be a smoother idling engine.  Well worth the effort!  Have fun and good luck.... :)

Oh... The screws from McMaster Carr are only available in packs of 100, so if anyone would like a new set of 4, (or more) just p.m. me and I'll send you some.  I'm sitting on a package of 100.  :laugh:

[Rikugun]

Great info and advice from Rich and Vintage - thanks guys!  :) Couldn't agree more, the payoff in overall fueling is well worth the little bit of extra work and expense. Also appreciate the part numbers/sources for seals and screws, good to know and I'll add to my list of reference info.  ;)

Rich, how confident are you in that Yammy seal number? It's listed (boats.net) for many models from 1970-2011 but I don't see XZ550 listed. Not that these parts finders are 100% accurate....  :( You've used them successfully? You are right about the price - seems to be nearly half of what motorcyclecarbs.com charges. This shouldn't surprise me as poking around that site I've been floored by their prices for everything. Hard to imagine a more exuberant use of the price gun than the OEM dealers but they've managed to do it.  >:(

edit: just occurred to me..price difference may be single lip vs. double lip design?

[vintage bikeworks]

The improved idle (smooth) will not hunt or surge, making carb syncs easier too! Just "sayin."   ;)

[AdvRich]

Hi vintage bikeworks. Nice follow up. I made an adjust in my original post to emphasize the correct #1 size phillips. Loctite 222 is a good choice too.

Rikigun, Yes on the seals. They are 8 x 11.5 and the ones I used to rebuild a set of '83 carbs some years back. I pulled out a seal again today just to confirm and to offer pics as well for pinholenz and others who've not ventured into the seals yet. They have the same single inner lip with an outer edge that flairs and finishes in a taper. They're the same on my TDM CV's and lots of other carbs with an 8mm shaft and a 11.5 housing well. They are the same ones VB refers to #5599 on this page http://www.motorcyclecarbs.com/Throttle_Shaft_Seals_C680.cfm One can choose the more seal edge options offered, but I don't think it will be an improvement over the stock ones which work just fine.

I did find motorcycle carbs prices rather high for all their parts and did not use them. I also ran into the same 100 lot screw option and found a work around with Ace for a couple of bucks. I thought it great to have an allen head for future removal and with the flat top that is flush with the shaft it would be more streamlined ;D then the oval head. They have the same tapered bottom just like the stock ones. The 3 x 8 size sounds correct too.

Also, I'll add that for my TDM carbs did not leak at idle when performing the squirt test. But they were a bugger to get the needles to behave equally at idle and off idle. I then scratched my head and gave a squirt with the carbs just off idle and low and behold the left one sucked it in on the outboard side. With the new seals in the sync went as usual and performed equally at idle and off idle. The old ones were toast - truly toasted and brittle. Similar condition for the '83 Vee set.

Hope this all helps guys,
Rich

Some pics for reference of the easiest of the four seals to access on the carbs. Sorry they're not any sharper.

Pop the clip to gain access. 


Remove the plastic washer and there's the seal.


Use a fine bladed flat screwdriver (computer/electricians) or dental tool to grab an edge and gently work it out. If they are really dry, you may just be able to pop the assembly against your cupped hand and it will fall out.


The seal and stock screw. The outer edge in the pic makes the seal appear to have a lip, when in reality it is the light shining on the outward flaring taper of the seal. Sorry, I couldn't find a pic of the flat top allens I used.

[QBS]

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.