Difference in performance/use RS Flat Slide vs CR Round Slide - wrist fatigue

All,

I'm currently running Mic RS34 FS on my 81 GPZ1100, and find them to perform fine, however, they are extremely heavy/stiff in operation.   I find I can't really blip the throttle fast and without heavy return springs they stick open.  I also get wrist fatigue after about 45 minutes and it just makes for an unpleasant experience.    I have adjusted them, reduced the spring tension, lubed the cables, routed the cables as straight as possible but it still is just too stiff.  What I'm thinking (and hoping) is that the CR's are less stiff and easier on the wrist.   I haven't used them before so I have no experience to go on, and would hate to buy them and find out they suck/are super stiff as well.   

Performance wise the RS34 are great, easy to adjust make great power.  I've even thought of making a servo helper or some kind of vacuum assist.   I know CV's are far lighter, the BS34, and I might eventually have to go that route.   There is noway I'm reverting to that lousy FI system though.  

My question is anybody running the CR's could chime in on their operation and extended ride use.  

Thanks
577Nitro

 

The RS throttle slider can bind under heavy vaccum to the carb body, so you need an extra throttle cable for closing. The Mikuni TMR carbs have slider bearings that didn´t bind!

wrote:

The RS throttle slider can bind under heavy vaccum to the carb body, so you need an extra throttle cable for closing. The Mikuni TMR carbs have slider bearings that didn´t bind!

Curious that Mikuni TMR 34's are not available.

How about changing the cable spool at the throttle for a smaller dia or a larger one at the carb end.
This will make for lighter operation.
The side effect will mean more rotation needed for full throttle though.

What a timely topic.
   My Mrs. was just complaining about this very thing. I have Keihin CR Specials on my Suzuki GS1100 and she has Mikuni RSs on her GPz1100. I noticed the Miks were more difficult to turn when I was commissioning the GPz after it went through rehab and conversion from factory FI to carbs. New carbs, new cables and new throttle tube, all lubricated correctly and laid down nice & straight without any kinks or binding. I reached out to Motion Pro (providers of the cables & throttle tube) for suggestions and Kellie's response was to check the installation manual for proper installation, and perhaps move the return spring to one of the "looser settings". 

   My Keihins don't have the same issues at all. Motion Pro doesn't have a smaller diameter throttle tube. I never considered a larger wheel on the carb rack. Any idea where one of those might be sourced?

Thanks KZR.

 

I have a set of Mikuni RS36's on my early model GSXR750 and a set of Keihin CR33's on my Kz1000 Superbike. I just went out to the garage and checked to see if there was any difference in the amount of effort it took to open both sets of carbs. I have the very same type of 1/8~1/4 turn throttles on both bikes. There is very very little difference between the two!!!
The RS36's take a tad more effort to open them. I am talking a very minute difference between the two. I never had to deal with any type of discomfort on long rides on the GSXR750 with that throttle. I use O.E.M. Kawasaki cables on both bikes. The GSXR750 uses Kz1000D1 (Z1r) cables 54012-1018 and 54012-1019. The Kz1000 uses Kz1000S1 cables 54012-1030 and 54012-1031. I must have tried 5 or 6 different length cables till I found the perfect length!!!

The GSXR750 uses the billet throttle from Yoshimura they offered for that bike many moons ago. I had a Motion Pro throttle on the Kz1000 at first. WHAT A PIECE OF JUNK!!!!! I even reworked the Motion Pro body to except O.E.M. type thread in cables. The Motion Pro throttle was like opening a bear trap. I scrapped it after I found an early billet prototype Yoshimura throttle. Both Yoshimura throttles use the very same throttle sleeves. As soon as I installed the Yoshimura throttle on the Kz1000 it was as easy to open as the GSXR was!!!!

My suggestion is if you are using a Motion Pro throttle and their cables I would scrap them. Find yourself a high quality 1/8~1/4 throttle and a pair of correct length cables. I have seen copies of the billet Yoshimura throttles for sale in a few places. When I say correct length cables what I mean as you move the handlebars from lock to lock they do not get get tight in one spot or put a sharp bend into the cables. The Motion Pro cables are no where near the quality of the O.E.M. brand cables. I don't want to tell you what I paid  for a NLA O.E.M. Kawasaki Z1r closing cable and clutch cable!!!!

The GSXR750 with the Yoshimura throttle and Z1r cables.
 

The Kz1000 with the Yoshimura throttle and Kz1000S1 cables.
 

Doc/Gamma/Bob:    Yeah I have one of those MP throttles, I found a couple high quality billet replacements that I’m looking at.   I don’t much care for it either.   

So to clarify, the extreme stiffness is when the engine is running, the vacuum of the engine pushes the slides hard against the carb body.  Being flat  the slides have a lot of friction and sticktion.   What I want to know, is when the engine is running during normal operation are the round slides easier to operate, IE: less vacuum friction.   

If anyone wants a set of RS34’s I’ll cut you a deal.  My wrist just can’t take it anymore…now that I’m an old dude.

577Nitro-

Changing the throttle tube diameter is the way to go.

This is the throttle I use on my KZ1000 and KZ750 -  both have RS carbs. The housing takes standard KZ throttle cables. you can then buy the throttle tube to suit your needs. I ended up buying a couple and tuning both bikes for the perfect balance of response and ease of control.
japan.webike.net/products/20874668.html
japan.webike.net/products/20874660.html

alternatively you could get a "cramp buster". they take a little getting used to but they work great. ive done some 18+ hours days with these.
www.crampbuster.com/

wrote:

Changing the throttle tube diameter is the way to go.

This is the throttle I use on my KZ1000 and KZ750 -  both have RS carbs. The housing takes standard KZ throttle cables. you can then buy the throttle tube to suit your needs. I ended up buying a couple and tuning both bikes for the perfect balance of response and ease of control.
japan.webike.net/products/20874668.html
japan.webike.net/products/20874660.html

alternatively you could get a "cramp buster". they take a little getting used to but they work great. ive done some 18+ hours days with these.
www.crampbuster.com/

Thanks Doc. I will give webike a shot. At least measure up the existing throttle tube. Much appreciated!

My VM 33's have a strong spring so my wrist got tired easy on long rides. I have a cruse control but I don't like using it in case I get into trouble. I have a cramp buster I use all the time. I modified my tube with a shim so the throttle will open faster off idle. There was a lag before the slides would open so it helped. In the past I used only one cable but installed the close cable so I could shut the carbs off quicker just in case. It made the revs snappier and that's the way it is today. 
Steve

Awesome...what a great idea!   Thanks!  

577Nitro

Doc/gamma/Bob:

I just wanted thank you for sending me on a fantastic goose chase trying to track down ancient, elusive, critically endangered 54012-1018/9 species of cable.    Thanks a lot Buddy!  

Holy Crap,  I think I found one in Germany, but I can't verify it's and actual OEM one.  It has a TKM marking on it, so if someone could check their real ones to see if it has that.  
Of course there is 10billion MP out there, there are some German made aftermarket ones, that seem pretty good...but I know nothing about them.  

The search goes on....

577Nitro-