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Tk26 throttle shaft seals

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17 Feb 2023 11:14 #880336 by Hucksawyer
Tk26 throttle shaft seals was created by Hucksawyer
Has anyone had a tk26 carb apart to replace the throttle shaft seals?  On start up it my bike revs up to 4k and after a little while it stops down but  doesn't seem 100% right even then. I've done all the o rings and cleaned the carbs thoroughly except these seals.  I'm wondering if they're the culprit. 

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17 Feb 2023 20:03 #880366 by Nessism
Replied by Nessism on topic Tk26 throttle shaft seals
I can't answer about the throttle shaft seals, but I do know that leaks from the carb boots is a far more common problem.  Some people think that spraying junk on the boots will find leaks, but in my experience it doesn't, unless the leaks are huge. 

BTW, I don't see throttle shaft seals listed on the OEM Kawasaki parts fishe, so where would you get them if they needed changing?

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18 Feb 2023 10:55 #880386 by Hucksawyer
Replied by Hucksawyer on topic Tk26 throttle shaft seals
I've found this, seemingly really good kit. It has throttle shaft seals

www.thecarburetorguy.com/product-page/ka...tk-diaphragm-rubbers

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18 Feb 2023 11:25 #880387 by Nessism

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19 Feb 2023 15:12 #880455 by Hucksawyer
Replied by Hucksawyer on topic Tk26 throttle shaft seals
I found a cheap enough, single tk26 carb on ebay. I tbought it to do a dissection to investigate further on the shaft seals

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19 Feb 2023 15:43 #880456 by Nessism
Replied by Nessism on topic Tk26 throttle shaft seals

I found a cheap enough, single tk26 carb on ebay. I tbought it to do a dissection to investigate further on the shaft seals

I've pulled throttle shafts on Mikuni BS32/34 and Keihin CV34 carbs before, and other than concerns about stripping the screw head, it wasn't difficult.  Interestingly, the Keihin's don't have throttle shaft seals.  They do have a nice fitting brass/bronze bushing for the shaft to ride on, though.  The Mikuni's use the seals, although they are hard to come by.

During reassembly, I actuate the throttle a number of times to self align the butterfly.  Hold it up to a light to make sure it's properly aligned and sealing.  Then use red loctite on the screws.  The backside of the screws is hollow, and designed to be flared out after install.  I made a special set of pliers with a pointy nub on it to get into the hollow and flare the screw.  You can see this idea for yourself by looking at the 1980 KZ750/4 manual, in the carb section.  There is a special tool to flare the choke plate butterfly screws.

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26 Feb 2023 10:48 #880780 by Hucksawyer
Replied by Hucksawyer on topic Tk26 throttle shaft seals
So I'm glad this was not one of my carburetors off my bike... there are casualties. 
There is only 1 shaft seal per throttle shaft it seems.  The side with the return spring.  The other side is sealed by the welch plug. The order of removal here would be butterfly valve screws and slide the plate out in the correct direction due to the bore taper for the venturi effect.  Then remove the welch plug. On the other side of the shaft, knock out the roll pin and pull the linkage and spring off. Tap the shaft out of the Welch plug side a little to remove the e-clip and under that is a metal washer and under that is a plastic washer. Then I would tap the shaft back in the other direction as the shaft seal came out on the shaft. 

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