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RS34 jetting

  • Thread starter Thread starter DFWSpeedster
  • Start date Start date
D

DFWSpeedster

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I just picked up a set of used RS34's off of a GS1000 on ebay, and I'm trying to figure out what main jets I should be using.

I have an '83 GS1100 with a stock motor other than a V&H 4-1. Currently have the baffle in but I may consider removing it down the road.
Thank you in advance!

EDIT: I'm at sea level
 
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around 120 / 122.5 or may need to go up to 127.5. no baffle? maybe as large as 135 -- it is hard to just throw a number out with out knowing the elevation as well as the engine mods.


The RS34-D21-K - came new with 115 mains and 17.5 pilot but they were jetted for GS750/KZ750/GSXR600

the pilot 17.5 should be fine - around here the needle works best at 1 below middle groove. - but that too could be different where you are.
 
Also, as far as air filters go, are the K&N filters REALLY worth it for how much they are?
 
I'm at sea level, I guess I'll just have to play with it. Luckily jets are cheap.
 
DFWSpeedster said:
Also, as far as air filters go, are the K&N filters REALLY worth it for how much they are?
Click to expand...

You can get APE pods for about half the price as the K&N's. I haven't tried them myself, but other members say they are as good as K&N. I use the K&N stock replacement filter in the stock airbox, and it's worth every penny to me.
 
You don't want to remove the baffle. Mine came loose dropped out lost forever. It was obnoxiously loud. Drove it home parked it and waited for a new baffle to arrive. As for the jet sizes you could look up a Dynojet stage-3 kit and use a conversion chart to get the Mikuni jet, equivalent sizes, they provide in the kit.
 
Just checked Dynojet and for the stage 3 with baffle in they recommend DJ138. The conversion tells me those are 130 Mikuni equivalent. Does that sound right?
 
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I would rely on the Dynojet recommendations. I am running VM carburetors with the DJ 142/Mikuni 133.1 jets. I am not familiar with your carburetors so I would just be guessing. I do know the main jet needles provided with my kit provides for smoother transition than a stock needle could. That information from the kit gets you in the ballpark.
 
K&N are worth the money - I have a set that are almost old enough to drink alcohol. keep cleaning them --

plenty of other brands - foam are cheapest and easy to clean/oil.

Now you own a set of mikuni mechanical radial flat slide carburetors - forget dyno-jet - they specialize in CV carburetors. jet numbers are all wrong too.


Mikuni tuning manual is a PDF online - RS series use the HS40 link.. you have what I believe to be the the best - most tunable carburetors under the sun- and every part ( should you need one) is available thru sudco or mikuni or K&L - there is an information overload at the other side of the links.

http://www.mikunipower.com/RS01.htm
http://www.mikunipower.com/Manuals01.htm
 
Awesome. Thank you for those! The RS36 chart for the GS1100 recommends 130 mains, so I think I'll go with those.

As for the idle mixture, only 1/4 to 1/2 of a turn? Someone else said 2-3 turns out

These carbs were always out of my price range, but after batting the float height with the 34mm carbs off of an 1100 katana I finally gave up and found these for roughly $400, and they look almost brand new!
 
The idle mixture screws work completely differently than those on CV carbs, I don't think 2 or 3 turns would be correct for RS's.
They are easier to tune than CV's each circuit works a bit more independent and over laps as you move from idle to redline.
Also put marks on your throttle grip at least at 1/4, 1/2, 3/4 so you know which circuit you are working with while you tune.
 
Hm, now I'm confused. This was taken from the tuning guide:

TUNING THE IDLE CIRCUIT (PILOT SYSTEM)The first step in tuning any carburetor is to getthe idle circuit correctly adjusted. And, the first step inthis procedure is to adjust the pilot screw position for bestidle. Mikuni sets the pilot screw at three turns open duringassembly. This is the position we have found to be rightmost of the time. If the screw position has been altered,gently bottom it and re-open to three turns out.
 
If thats what it says thats what it says!
You will know right away, it shouldn't make too much difference to get it running, then tune the screws for highest idle.
I always thought 3 turns on RS series carb meant go down a size on the pilot jet. But follow the directions.
 
We'll know hopefully in a few days after I put everything back together, just trying to do everything I can without them on the bike. We'll see! Thanks for the throttle grip marking idea!
 
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Keep in mind ( Im sure you know) that CV carbs are RPM dependent and the RS's you have are Throttle position dependent?. Don't use CV tuning tips for RS carbs.
Other here have to know a lot more than me about timing RS's
 
Ignore the Dynojet stuff, absolutely irrelevant to RS carbs. I had some of those RS34 years ago, try 122.5 mains and see what you get to start off with. As far as the pilot screws, they should be 1/4 to 1/2 turn out, NOT 3 turns. Again, NOT the same as a CV carb.

Important, if you only have a single-cable throttle, get a push-pull throttle for it. The RS slides get a strong vacuum signal and can sometimes hang open, which means you let off the throttle on the handlebar but the engine doesn't slow down.
 
That sounds better. These came off of a GS1000 and the mains are 110's. I thought it was weird that Mikuni's RS tuning guide gave the entire range from GS1000-GS1150 and recommended 130 for all of them.
 
I love the sound at idle -- clickety clack..

I love the sound at idle -- clickety clack..

from the MIKUNI PAPER it shows the pilot mixture screw range of operation is 1/4=0.25 turn (lean) out to 3-1/2=3.5 turns (rich) from gently seated closed. - more than 3 turns get a bigger pilot jet - less than a quarter turn get a smaller pilot jet. I prefer to be close to 1 turn - and balance it with the needle setting - that allows you to control the fuel better (overall) and at a later date if the weather changes you can have a more effective adjustment with only the mixture screws - (nevermind the advanced tuning)

the 17.5 pilots may be too rich for your engine - you will have to experiment using a lean idle drop procedure-- not every mixture screw has to be exactly equal (example 1.5 across the board) - you have to find the best mixture setting for each individual cylinder - if you almost have to seat the mixture screw closed -- or cannot get a distinct idle drop - get some 15 pilot jets.
- just get it to idle within the mixture screw range first -

needle height adjustment and re- sync go hand in hand - if you change the needle you have to re-sync every time- that is true on ALL mechanical slide carbs. -- #3 is the base you dial the others to. getting good with the ramped adjuster mechanism takes practice.


float height works best at 17mm -- not 19 like the picture shows - there may have been some changes to the newer model body castings or it is a typo because the book that came with my set shows 17 and it works on all the sets I have - 34/36/38/40 - yes I have too many carbs. no I'm not selling.


110 may be great for your engine on the street. you are going to have to test and re-tune.

spark plugs are cheap and all carb parts are easy to get. ever have trouble contact me.
 
Thanks for this. So even though these came off of a GS1000 I should start with the 110's on it? I haven't looked at the pilots yet, so I assume if they work for a gs1000 they probably wont be too rich for me?
 
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Can anybody point me to a synchronization guide for these carbs?
 
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