Why you should replace butterfly (throttle shaft) seals.

So it is cold and raining off and on so no riding , I finally tore into a spare set of carbs I bought awhile back from Joe Elif . They were pretty gummed up and very dirty inside and out ... I like challenges I only wanted these a spare anyway. (Always like spares parts ) so got one carb tore down and soaking , when I pulled butterfly shaft out the seals were toast , I suspect at some point someone tried to soak carbs and this will tear up the seals . There is NO short cut breaking the carbs off the rack is only way ,and one other seals that is super critical is the fuel interconnect rail ....do your carbs right the FIRST time if it leaks fuel onto a hot engine well I dont think I need to explain. Anyway not sure about other carbs, when I rebuilt my carbs(on my seca ) seals did not look real bad but replaced anyway .

 

no such thing as spare carbs, just carbs in waiting. now you have to find a bike for them its the right thing to do..

replacing the seals is needed and you should not have to do it again for several years

 

Mine had 18k miles and looked ok but they were not contacting the shafts at all.

 

Exactly.
Over time the plasticizers migrate into the atmosphere, causing the seals to shrink and embrittle.
The process speeds up with exposure to ultraviolet light and/or heat.

Stickied and edited the title for terminology.

 

So here are some pictures of the carbs before and after one is cleaned . The #4 carb float post was broke at some point , who ever did the repair did a good job drilled hole and put a pin in and JB weld . I have another set of carbs so will probably not use this body , but I might use it as is.

 

So grabbed my other set of carbs , broke down the carb number 4 , got it soaking right now . Looking at this set of carbs there in better shape but were missing the diaphragms. The other set has diaphragms and complete.

 

When I pulled my carbs apart, I found my throttle shaft seals to be petrified. They LOOKED ok, but they were hard as a rock. No chance they were doing the job they were supposed to be doing.

 

I'm hoping this thread will better show why you should take carbs to church . My second set I tore down today seals were soft and pliable look new , but I'm replacing them anyway.

 

Okay finally finished putting carbs back together only took me 3 months ( lol has been to cold to work in garage and was in no hurry either) these carbs were in poor condition , extra soaking on one carb the butterfly seal was totally goo , the butterfly plates were seized and the slides were froze took lots of PB blaster to free them up. The hats were rusted and I'm cheap so cleaned them up ,sprayed with self etching primer and painted with hammer rite silver

 

If you have the parts and pay attention to the shaft styles and orientation it really is not that bad. Just time consuming when things break during disassembly.

 

I recently tried out the two #11 o rings for throttle shaft seals on my 83 750 midnight so I could get it on the road for cheap. Well, that completely backfired in my face. When I first put them together I had coated the orings in silicone grease and all worked smoothly. A month later and the throttle blades no longer operate properly. They open well enough but take about a minute to return to an almost idle position. My advice, buy the correct seals and do it once. I am so mad I have to pull those flipping carbs again. One because it's a pita, and two because I have it running so awesome.

 

You do have to work the throttle shafts quite a bit initally when using the o-rings in order for them to work properly.
Maybe @Polock can chime in about that to clarify. I believe that he's had the same set of o-rings in this machine for several years.

 

he has advised me that using 2 #11 x rings works with out working the carbs

just work them a little more you may not have to redo them

 

Spray a quick shot of fluid film in the crack of the shaft where it meets the bore. then work them and repeat. the lanolin should last a bit longer until the rubber molds to the shaft.

 

sorry to hear about that. here's the o-rings out of mine after, i don't remember how many years. the slides snap shut like a guillotine.
the grease should be similar to this stuff, clear and a bit thicker than toothpaste. spray can silicone attacks the rubber.

 

Could be wrong O ring material , Buna or vitron is they type.

 

I'm having difficulty locating accelerator pump seals. I'm getting ready to do an overhaul to replace the shaft seals, Jets, floats, needle and seat, air fuel mixture screws. I have been unable to locate accelerator pump seals. As all have suggested, I would like to replace the rubber on these. Any ideas for a source.

 

what kind of carbs are they? chances are they don't have accelerator pumps

 

I think you may be thinking the choke piston is a fuel squirter?

 

And the seals on the enrichment plungers (pictured above) are just dust seals.

 

xj4ever sells those too

 

So here is the thing... I know that Chacal (xj4ever) is a good source for a lot of this stuff, but unfortunately because of the exchange rate and shipping ordering from him can be QUITE costly for such small objects.

With that said I see in this post people have talked about using #11 viton orings as throttle shaft seals, but has anyone measured out what a double lip or what size of seal would be necessary to replace the ones that are in there?

Maybe something with some precise instruments who has their carbs ripped apart could give us depth, width and opening sizes and maybe find something that is easily accessible to all?

 

I did measure mine with a caliper and mic but I didn't write them down. I ordered square seals that were supposed to fit and went with it. They were a little loose in the bore but squished and fill it when I installed the shaft clips and such. We'll see if they come back to haunt me. I have some 550 carb parts sitting in a tote that I can measure tonight and post dimensions.

 

The cost of the correct seals seems insignificant to me compared to the labour (my time) to go back in there.
Order new butterfly screws while you're at it.

 

Doubling up the #11 seals works fine ,in my spare set of carbs , my main set has the seals fro XJ4Ever ...I would rather use the seals from Chacal.

 

11.5mm OD
8mm ID
3mm thick

 

I agree with the consensus to just replace them with the correct seals, if at all possible. I just rebuilt my carbs for probably the fourth time in 18 years (and this time it's been 10 years). Although I was expecting the throttle shaft seals to be brittle or slightly disintegrated -- I seem to remember using petroleum-based lubricant last time -- I was somewhat disappointed to find them in nearly new condition. But you better believe that while I was in there, I still replaced them and used the correct non-petroleum-based lube.

 

I am thinking about pulling my carbs and rebuilding them very hard to start and takes for ever to warm up. Was looking at the seals cost a lot to have them sent so was thinking about o rings found some online. After it starts have to run on full choke and give throttle slowly or it bogs out bad and have notice cutting out under 2500 rpms and what sounds like a slight ping about half the time. will these work?

3 mm X 8mm (NBR) Buna-N 70 Duro Metric O-Ring
3mm Cross Section

 

#11 orings is the size and can be combined with #11 x rings 1 of each on each side

 

Keep trying to find #11 O rings when I do a search they do not come up as #11 . trying to find the size for them.

 

https://www.mcmaster.com/o-rings
search
9452K19

 

Thank you found them you dont have the # for the x rings do you .I think the reason I couldn't find them I was looking up # 11 o rings and it came up with 3/4 OD or 9/16 OD
I knew that wasn't right.

 

90025K135

 

Thank you

 

got them in the mail had to buy a 100 of each but only $11.00 for all so very happy.Looking thru post dont guess it makes a big difference what one goes in first.

 

don't think it matters, just use something like this to grease them up on install
https://www.homedepot.com/p/Super-L...ing-Grease-with-Syncolon-PTFE-92003/202932697

 

thanks

 

Planning on doing this job on bike soon. Just to be clear, I should replace the O-rings AND throttle shaft seals? Those are two separate things? I've already ordered the o-rings and I've emailed xj4ever about ordering a set of throttle shaft seals. They're quite expensive but worth it to fix a vacuum leak.

 

Bought the x-profile O-ring that polock suggested. Did you mean to use these in replacament of the actual throttle shaft seals or as the correct o-rings on the fuel line?

 

The o-rings mentioned in this thread are viable alternatives for the proper throttle shaft seals (which I prefer).
The o-rings came about at a time when new throttle shaft seals were very difficult to get at a reasonable price.

The fuel fttings take a somewhat specialized seal, and I recommend against substuting anything else.

 

I had no issues fitting viton o-rings in my rebuilds. The V seals are available but they are overpriced and only do a slightly better job at sealing. They do a much better job of splitting than the o-rings do, though.

 

Sometimes it is best to order the best cry once. In other words do the job right the first time , and KMOE is spot on get the CORRECT fuel rail seals , you do not want a leak at these points can lead to a fire.

 

@Jetfixer does anyone know the correct size for the fuel rail o-rings?

 

#10 fit the Hitachi's on the XJ700.

 

My fault, should've started with for an '82 xj650 maxim. The carb for that one is a hitachi HSC32

 

WARNING, REDNECK FIX
i found a o-ring that fit tight in the groove on the fuel pipe but didn't quite go into the carb. then i pushed harder, then really dam hard and it went in, and cut a little sliver of o-ring off as it did
they haven't leaked in years.
i don't recommend this, but i can't argue with success.
your really better off with the real ones

 

Xj4ever has the correct seals , although they look like "O" rings they are flat on the outside and when you put the rail into the body you will feel a slight snap that locks them in place. My local Yamaha dealer actually had them as well. I can't recall price .

 

wow ... I just broke down the carbs and replaced the throttle shaft seals with #11 rings. It worked good for about 10 minutes, then hung up and had to shut it down to get throttle to snap back. I used silicone on rings on reassembly but now I am thinking I will have to break down carbs again to see whats hanging up. I cannot sync carbs in this condition

 

am i the only one who did the o-rings successfully?

 

Did you work the throttle linkage to "bed" the o-rings in before you installed the carbs?

I know that others have. I uesd o-rings on my friends Virago without any trouble.