(BS series) Throttle Seals: Who's done 'em, who needs to?

I'm getting ready to re-assemble my throttle shafts, new OEM seals, springs, washers, valves, etc.

Is there any need to apply any sealant or any other type "goop" or juice around the seals or is everthing done "dry"?

Aside from my parts, I don't want to find out later that I missed applying/installing something and then having to take everything apart.

Thanks.
 
You don't have to put anything on them but if you have any sort of rubber lube, you could use that, even some WD40 so they're not going in dry. You don't want any type of actual gasket maker or sealer on them. These seals work on vacuum. You'll notice they're not the tightest fit either in their hole or around the shaft. The vacuum generated through the carb's main bore sucks them in and tight around the shaft. To work best, they need to be soft and pliable. That's why they fail and need replacing - they harden up with age.
 
10-4, 5twins.

I've been looking for a past post of yours that showed an image of your twin carbs in a pipe clamp. I think it related to the throttle shafts, perhaps removing stuck screws, I don't recall and can't find it. Do you recall the image, and if so, can you describe what you were doing?

Thank You.
 
Yes, that wouldn't apply to your carb set. That is for pressing the fuel "T" into the 34s before tightening the brackets that hold the 2 carbs together. If you don't do that, the fuel "T" will be loose and leak. Your carbs don't have the "T", they use separate fuel lines to each carb.
 
I just ordered 4 Yamaha OEMs from my local dealer, should be here the beginning of next week. I'm subscribing to follow.

For the butterfly screws, JIS works the best to get them out, do they have to be deformed or will loctite be adequate to keep them in place? Do we have any long term on this?

~ Derek
 
Don't want to beat this "best throttle shaft seal"...."butterfly seal" thing to death but so far
it really does seem that the OEM Yamaha part # 256-14997-00-00 is the best way to go.
I've done a search (as have others) and so far the best price I've found is....

http://www.powersportsplus.com/parts/detail/yamaha/YP-256-14997-00-00.html

Check that list of models on which they were/are used. Best, Blue
 
What do you guys think of these?

They are stainless alan head screws, and I was planning to locktite them in. Any thoughts?

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Only to be careful with how tight you go, AFAIK the shaft is not steel it is chrome plated brass.

Follow 5 twins advice about snapping the throttle shafts shut a few times to center the butterflies before the final tightening

Other than that I LIKE the socket head.
 
DeftQuiver,
I have a set with carbon steel allen heads and blue loctite.
I did put some on both the threads and head bevel. Just a little.
No problems.
 
You could reach in with a set of side cutters/dykes if you want to "stake" the threads.
 
I'm in the process of doing seal's on my 34's and found this trick, so I'll pass it on.
My butterfly screws were very tight and still had the factory stake[heavily staked!]
My carbs are completely dissembled so i taped the small bypass hole's with masking tape.
Then stuffed a shop rage in the carb behind the butterfly to prevent any contamination.
I drilled the stake portion down flush with shaft. Cleaned with 2+2 and compressed air, went to remove screw's and viola no go! AHHHHH!
Next brain storm was a reverse drill bit/easy out, shazaaaam! came right out..FYI
Hope this makes sense and helps someone!
 
DeftQuiver said:
What do you guys think of these?

They are stainless alan head screws, and I was planning to locktite them in. Any thoughts?

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This photo makes me want to play golf.

OGIO bag in the background.

drive for show, put for dough......ride for life.....look out below.....
 
I think I may prefer golf as well as compared to trying to "booger" a stainless steel screw of that extra length. I found that cutting a small "x" across the end of a shorter brass screw and then (after final adjustment prior to tightening...checking for smooth operation and dual closure....staking (spreading the X cut quarter pieces outward to "booger" the screw ends (much easier to do with brass) to be about as much as I'd care to handle in such tight quarters.

I can't think of a single task where the exact fit of a JIS screwdriver tip is more important than the one of removing those JIS OEM Mikuni butterfly cross-points btw.

Blue
 
Blue, I was with this as gospel, but I just did 4 butterflys, and my #2 philips bit from Irwin fit these screws better than the the JIS #2 1062 Vessel bit I special ordered. I am still waffling on the best way to be sure the screws don't back out. Good and tight is my mantra for now.

Plus a couple on not doing final tightening of the butterfly screws until AFTER the throttle cable arms and springs are bolted back on, the idle screws backed out and the shaft "snapped" closed a few times.
 
The fit is the thing for sure but for what it's worth on the butterfly screws per se I use the Vessel # 1 or 1061 I think....regardless, don't buy one I'll send you the set 00, 0, 1, 2, 3 when I send you the water traps probably next week. Best, Blue
 
You had already sent me a set, it still has your business card stapled to it so you can't deny it! And I bought a set before that, and got 4 more 1062's from Mcmaster Carr. I'll check the 1061 bit. I have one more fly to put back in yet. Just doing my first "early" set of BS38s today. Getting the o-ring on the emulsion tube is very fussy on the early ones.

Thanks! Gary
 

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