RS34 and BS34 Choke Plunger Size Comparison

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RS34 and BS34 Choke Plunger Size Comparison

28 May 2025 19:41
#912997
BS 34 shown on right:



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1982 KZ1100-A2

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Re: RS34 and BS34 Choke Plunger Size Comparison

28 May 2025 19:56
#912998
I've never seen BS choke plungers that look like your photos.  Every one I've seen is like the units on the left.  

Never seen an RS plunger, so can't comment.
Ed
Carb O-ring Kits : www.kzrider.com/forum/3-carburetor/61807...-o-ring-kits?start=0

www.kzrider.com/forum/faq-wiki/618026-new-owner-things-to-know

1981 KZ750E2
www.kzrider.com/forum/11-projects/604901...z750e-project-thread

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Re: RS34 and BS34 Choke Plunger Size Comparison

28 May 2025 20:53
#912999
Another view:
 

BS has a brass retainer nut, and RS nut has a black coating.

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1982 KZ1100-A2

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Re: RS34 and BS34 Choke Plunger Size Comparison

29 May 2025 00:43
#913006
Yep! Had loads of both come through my hands for repair.
There's a few other variations throughout the Mikuni range and then there's the Keihin and other carb makes too.
AIR CORRECTOR JETS FOR VM CARBS AND ETHANOL RESISTANT VITON CHOKE PLUNGER SEAL REPLACMENT FOR ALL CLASSIC AND MODERN MOTORCYCLE CARBURETTORS
www.kzrider.com/23-for-sale/611992-air-c...lide-mikunis?start=0





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Re: RS34 and BS34 Choke Plunger Size Comparison

29 May 2025 04:49 - 29 May 2025 04:49
#913012
Wow!  I learned something here!

Partzilla says the following bikes used those same plungers.  I've rebuilt some sets of 1000 and 1100 BS34's, but apparently I didn't look close at the plunger seals.

Kawasaki2002 KZ1000C/P Police 2001 KZ1000C/P Police 2000 KZ1000C/P Police 1998 KZ1000C/P Police 1997 KZ1000C/P Police 1996 KZ1000C/P Police 1995 KZ1000C/P Police 1994 KZ1000C/P Police 1991 KZ1000C/P Police 1990 KZ1000C/P Police 1987 KZ1000C/P Police 1985 KZ1000C/P Police ZX750 GPZ 1984 KZ1000C/P Police ZX750 GPZ 1983 KZ1000A/J KZ1000C/P Police KZ1100L LTD Shaft KZ750K LTD Belt ZX750 GPZ 1982 KZ1000A/J KZ1000B/K LTD KZ1000M CSR 1981 KZ1000A/J KZ1000B/K LTD KZ1000M CSR KZ1100A
Ed
Carb O-ring Kits : www.kzrider.com/forum/3-carburetor/61807...-o-ring-kits?start=0

www.kzrider.com/forum/faq-wiki/618026-new-owner-things-to-know

1981 KZ750E2
www.kzrider.com/forum/11-projects/604901...z750e-project-thread
Last edit: 29 May 2025 04:49 by Nessism.

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Re: RS34 and BS34 Choke Plunger Size Comparison

29 May 2025 07:31 - 29 May 2025 07:32
#913016
Note the BS plunger seal distortion from forty-plus years of deterioration and constant spring pressure:



Might help to pull out the choke rod as one shuts off the fuel after each and every ride...in a good-faith effort to save the seals, before it's too late.
Lol

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1982 KZ1100-A2
Last edit: 29 May 2025 07:32 by daveo.

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Re: RS34 and BS34 Choke Plunger Size Comparison

29 May 2025 10:33
#913028
daveo wrote:
Note the BS plunger seal distortion from forty-plus years of deterioration and constant spring pressure:
 
The BS plunger seal is actually molded like that with the "raised " ring being the normal thickness and the surrounding surface being recessed.
I see no real reason why they have done that as it makes no difference to the seat pressure whether the seal is contoured or flat and my replacements work perfectly without.
AIR CORRECTOR JETS FOR VM CARBS AND ETHANOL RESISTANT VITON CHOKE PLUNGER SEAL REPLACMENT FOR ALL CLASSIC AND MODERN MOTORCYCLE CARBURETTORS
www.kzrider.com/23-for-sale/611992-air-c...lide-mikunis?start=0





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Re: RS34 and BS34 Choke Plunger Size Comparison

29 May 2025 13:08 - 29 May 2025 13:11
#913044
Huh...really great mention there Rob.

Seems Mukini figured out that unnecessity by the time the RS carb series came to be, whenever that was.

The RS34 's have proven their worth since my rack was recently ultrasonic-cleaned of ten years plus accumulated particulate crap, and having the jetting sorted out as well.

😱

 
1982 KZ1100-A2
Last edit: 29 May 2025 13:11 by daveo.

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Re: RS34 and BS34 Choke Plunger Size Comparison

30 May 2025 06:59
#913078
Niche Cycle has a good selection of plungers.
www.nichecycle.com/catalogsearch/result/?attr=0&q=plungers

Good Ridin'
slmjim & Z1BEBE
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Re: RS34 and BS34 Choke Plunger Size Comparison

30 May 2025 07:40
#913087
slmjim+Z1BEBE wrote:
Niche Cycle has a good selection of plungers.
www.nichecycle.com/catalogsearch/result/?attr=0&q=plungers

Good Ridin'
slmjim & Z1BEBE
YES!
You have to be aware though that these replacements still use NBR/Nitrile rubber for the seals so are not suitable for fuels containing ethanol.

 
AIR CORRECTOR JETS FOR VM CARBS AND ETHANOL RESISTANT VITON CHOKE PLUNGER SEAL REPLACMENT FOR ALL CLASSIC AND MODERN MOTORCYCLE CARBURETTORS
www.kzrider.com/23-for-sale/611992-air-c...lide-mikunis?start=0





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Re: RS34 and BS34 Choke Plunger Size Comparison

30 May 2025 07:57
#913089
What about the diameter of the plunger?  Are these "raised lip" plungers the same diameter as the regular BS34 plungers?  

I went through my hoard of old plungers and replaced the rubber in all of them.  Sort of proof of concept that I could do it effectively.  I took a damaged VM and another BS plunger, cut the crimped edge off, then measured the cavity diameter.  That helped greatly, in sizing the rubber donut.  Wish I could find Viton grade B sheet here in USA, but it's elusive.  I'm using grade A, which seems to work fine, but it's not as resistant to oxygenated fuels as the grade B stuff.  Better than what was used 50 years ago, though.  
Ed
Carb O-ring Kits : www.kzrider.com/forum/3-carburetor/61807...-o-ring-kits?start=0

www.kzrider.com/forum/faq-wiki/618026-new-owner-things-to-know

1981 KZ750E2
www.kzrider.com/forum/11-projects/604901...z750e-project-thread

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Re: RS34 and BS34 Choke Plunger Size Comparison

30 May 2025 08:13
#913090
Nessism post=913089 userid=14026What about the diameter of the plunger?  Are these "raised lip" plungers the same diameter as the regular BS34 plungers?  

I went through my hoard of old plungers and replaced the rubber in all of them.  Sort of proof of concept that I could do it effectively.  I took a damaged VM and another BS plunger, cut the crimped edge off, then measured the cavity diameter.  That helped greatly, in sizing the rubber donut.  Wish I could find Viton grade B sheet here in USA, but it's elusive.  I'm using grade A, which seems to work fine, but it's not as resistant to oxygenated fuels as the grade B stuff.  Better than what was used 50 years ago, though.  
Don't know how bad you want this stuff Ed, below is details of a UK supplier that lists it 

1982 KZ1000 Ltd
www.kzrider.com/forum/11-projects/617631...-82-begins?start=192
kzrider.com/filebase-alias?view=download...d-fault-diagnosis&ca
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