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TOPIC: Mikuni RS34 carbs

Mikuni RS34 carbs 08 Nov 2019 15:20 #813718

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In case anyone is on the fence on getting the RS series carbs, do it. I just installed the RS34 onto my KZ900 and what a difference in power, Wow! I was running a set of VM26 bored to 29, the bike ran great but it just felt I was leaving some power on the table. I bought the 34 and dialed them in today, judging by my butt dyno I swear I gained 20HP. It carburates clean and pulls really hard from idle to redline. It feels like the bike is "uncorked" now. It'll rip my arms off when I really get on it, it's pretty addicting. I've run a set of RS36 on my ELR clone and was not disappointed with those either. Here's my jetting and mods to the engine.
1075cc MTC 10.5-1 comp pistons
Head porting
Yosh drop in cams .395 intake .385 exhaust
Vance & Hines 4-1 exhaust
Oil cooler

Mikuni RS34
125 mains
22.5 pilots
Needle in the middle slot
P-4 needle jet
Needle PDZH1
Float level set with the wet clear tube method at the top of the float bowl. That is 23mm float setting. Mikuni recommends setting them at 17mm but to me that seemed really high when I clear tubed it that set the fuel level about 2mm below the overflow tube so I lowered it. Haven't found a running issue with lowering it.
Idle mixture screw 1/4 turn
This gets me just about perfect. I've yet to vacumm synch them but they idle pretty good.

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Mikuni RS34 carbs 08 Nov 2019 16:02 #813722

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Same experience here. They work great and really wake these old bikes up. I was running 29mm smoothbores my KZ1000 prior. I also have a set of RS34 carbs on my KZ750 twin and that thing completely transformed. In the instance of the KZ750 twin they saved about 3 pounds in weight as well. I know some people don't like the sound they make but I love the rattle when you roll on the throttle.
-Vic
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'80 kz750G project

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Mikuni RS34 carbs 08 Nov 2019 16:49 #813728

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Another vote in favor of the Mikuni flatslides. I have a rack of RS34's on my warmed over KZ1000 LTD. Also, have a pair of RS34's on my '70 Triumph Bonneville (now 750cc w/ported head and cams). The throttle response is crisp on both setups. And the KZ really comes alive at higher rpms. No complaints here.

Presently - 1980 KZ1000B4 LTD w/mild ported head, Megacycle cams, 1015cc Wiseco, Falicon Supercrank, R&D undercut trans
In a former life - KZ-based dragbike - CrMo car tire chassis, 1395cc, Hahn Racecraft turbo system, VP C16, Orient Express 3-spd auto, 7.80's @ 165-170.
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Mikuni RS34 carbs 08 Nov 2019 20:28 #813738

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Like baldy110, I had the floats adjusted to lower the fuel level at one point, but decided to reset them to 17-18mm. per Mikuni recommendation.
Had to bend the tabs an awful lot to achieve 22mm, and it just seemed awkward to do something that Mikuni had not suggested in the manual. Nowhere could I find a reference to use the clear tube method for the RS carbs, or to set the levels 2-3mm fuel level below the bowl top. I did use the clear-tube to verify that the levels were the same across the set...

I found this nice little tool that makes on-bike main jet changes a breeze:



;)
1982 KZ1100A-2 (sort-of)
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Mikuni RS34 carbs 09 Nov 2019 13:35 #813750

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Yeah the ease of tune-ability is a major bonus. Changing the needles can be done with the carbs on the bike rather than dissembling half the rack. Heres RS-34s on my kz750 twin. The stock carbs on the twin are terrible in comparison.

Attachment kz750_8.jpg not found

-Vic
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'78 kz1000 LTD long term project

'80 kz750G project
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Mikuni RS34 carbs 09 Nov 2019 15:53 #813756

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The ease of tune-ability is awesome, but a pain to access with an air box in the way.

I recently reconfigured my air box to fit velocity stacks and RAM AIR filters. Once those have been removed through the air box, access to the Pilot Air Jets becomes unobstructed. Those jets are a pain for their size, but especially to get their tiny threads aligned and started correctly.




:)
1982 KZ1100A-2 (sort-of)
1135 since 10/25/19
January 2016 BOTM
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Mikuni RS34 carbs 10 Nov 2019 16:42 #813821

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I like your air box idea, really clean. Am curious Dave what was your final carb settings and what did you do to the engine?
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Mikuni RS34 carbs 10 Nov 2019 19:38 #813831

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baldy110 wrote: I like your air box idea, really clean. Am curious Dave what was your final carb settings and what did you do to the engine?


115 Mains
17.5 Pilots
0.7 Pilot Air
Stock Needles-Center Slot.
Stock Needle Jets
Pilot Fuel Screws-1/4 Turn
KRS-004 Mikuni Stacks

117.5 Main Jets messed with the low-end jetting, so I put back the 115's before pack-down. Will likely play with the jetting again in the Spring.

Engine is stock other than:
G1135-3 MTC piston kit w/cyl. bored and prepped by Pit Stop Performance.
Stock ZN1100 bath tub head milled .005 in 2015 for flatness; valves/seats touched up and Viton seals installed.
1984 ZX1100A camshafts using the stock ZN shim-on-top valve buckets.
APE Cyl Studs/Nuts, and Cam-Chain Adjuster
Non-Smog Cam Cover
Some Chrome

Bike is stock other than:
Dynatek 2000 with Mini-Coils, Copper Wires, Res-Caps, Non-Res U-Groove Plugs.
V&H 13009-J Header w/Street or Comp Baffle
Shindengen SH775
Progressive Shocks (12.5"), and Fork Springs
HEL SS Brake Lines
Pingel Petcock
160 MPH Speedo


:woohoo:

Shoot, now I want to go for a ride. :evil:
1982 KZ1100A-2 (sort-of)
1135 since 10/25/19
January 2016 BOTM
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Mikuni RS34 carbs 10 Nov 2019 20:04 #813834

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AND SHE MOVES :woohoo:
Z1b1000 1975 Z1b
Opinions expressed by me do not reflect those of the the staff or members
kzrider.com/forum/11-projects/598262-kz-...-will-it-live#672882
kzrider.com/forum/2-engine/597654-poser?start=240#704229
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Mikuni RS34 carbs 15 Nov 2019 09:01 #814025

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SWest wrote: AND SHE MOVES :woohoo:


;)

Need more user information and tips for RS carburetors from members that have them.

I purchased a used set of RS36's early in 2016, and replaced them with RS34's later that year.
Despite the good-wisdom of forum members, I followed the Mikuni application chart which recommends the RS36 for a KZ1100.
kzrider.com/forum/3-carburetor/601972-mi...s36-d3-k-application

Stock KZ1100 carb manifolds are made for 40mm spigots which RS34's (and BS34's) have. RS36's spigots are difficult to fit them since they are 42mm.

Attachment IMG_2085.JPG not found


This old chart misinformation has since been corrected.

:)
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Mikuni RS34 carbs 17 Nov 2019 11:08 #814098

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Typically my engine needs to be fully heated up before the idle stabilizes, and I no-longer need to adjust engine speed with the idle knob. :evil:

Anyone else dealing with this?

:whistle:
1982 KZ1100A-2 (sort-of)
1135 since 10/25/19
January 2016 BOTM

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Mikuni RS34 carbs 17 Nov 2019 15:09 #814107

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Once my idle speed is set I don't ever have to touch it hot or cold. I don't have an erratic idle it's smokth when warm. Have you vacuum synched the carbs? When cold I just use the throttle to keep idle up till warm.
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