rs34's

I have a new set of RS34's on my GS1000. I went with the 34's since the bike is stock displ. Running pods with a V&H 4-1 header. I thought I'd rather be a little to small on the throat than too large since I was looking for rideability and throttle response. I don't spend much time at WOT. I'm running the needle clip on 4th down, and 130 mains. Pilot circuit is stock. Runs sweet with great throttle response. In fact bike has never run this good.

Post edited by: BlackStar, at: 2007/08/27 19:24

that realy good news.most reports have be a lack of responce below 4000rpm.how do these compare to the stock carbs and are there any week areas?

Response below 4000 is good. No weak spots that I have found yet. My opinion is that going with the 34's instead of the reccomended 36's keeps the velocity up for good throttle response (I could be full of $hit here, I don't do this for a living). I don't have any experience with bikes and too large of carbs. I do have experience with cars that have had carbs sized too large for the engine,very mushy feeling. I think these carbs have sharper response than the stock carbs. There is the slide rattle. They do clatter at certain RPM/Load conditions. I'm glad I rode the bike with the original carbs so that I know all the noise is not the motor clattering! I also ride a roadstar warrior with a patrick racing air intake system so I'm used to induction noise. I think an earlier post eluded to the slides being plastic, they are in fact metal. I bought mine from Pingel enterprises. < $600.00. Pingel is great to deal with. Best fuel valves in the world too. Oh yea, There is a lot less hissing from intake air with these as well, the stockers hissed like heck. I'm thinking probably less turbulence in the throat?
These things are sooo easy to change jetting. I did a jet needle change last week in 20 minutes (all 4)with the carbs on the bike. No need to remove throttle shaft, slides, destroying your sync. That alone goes a long way. Most people probably wouldn't spend that much for carbs for this old of a bike. My uncle bought it new in April of 1978 and handed it down to me May 07. I could never sell it, so I'm in this relationship Looong term. I plan on riding it for another 30 years. (I better stock up on a few spares)
I know a fellow on the GS forum that bought a set from ebay. The float posts were broken off and improperly repaired. after a few days in gasoline, they failed. So beware of cobled up junk out there

Post edited by: BlackStar, at: 2007/08/28 20:30

Post edited by: BlackStar, at: 2007/08/28 20:34

thanks blackstar.u are the 1st to report on 34's.most ihave heard from have 36's.i heard from a guy with rs32's today.he says they work great .i didnt even know they made 32's.

Not sure if this is still of interest to you Mark1122 but thought I'd share my RS34 experience.

I installed them together with a web drop-in cam (.365 lift) on a 79 kz1000 a few years ago. Since then I've installed a 1075 kit and have experimented with a V&H and Jardine 4-1 exhaust. I've also spent lots of time testing, tuning, riding and dynoing this motor.

My experience is that the RS34s are great and will provide excellent throttle response, midrange and top end power IF the rest of engine is set up properly. Here are a few things I've found through experience:

* 1000cc is plenty of displacement for RS34s

* It is well documented that RS34s "clack" at idle. This is normal. If they clack while cruising, this is an indication that your engine is reverting (air and fuel in the cylinder are re-entering the intaked port causing positive pressure pulses in the intake). Flat slide clacking is very helpful in detecting reversion at different RPMs. Your carburetors and engine will perform very poorly if they are reverting. Reversion will cause these (and other) carbs to bog when the throttle is cracked open and there is no way to tune this out through jetting.

* don't "hog out" your intake ports. This will reduce air velocity in the port and promote reversion. Mid range torque, throttle response and drivability will all suffer. Cleanup, port matching and a professional 3 angle valve job are all that is necessary to prepare a KZ port for street use.

* Exhaust tuning is critical. I've been able to get good results from both a V&H pipe and my Jardine pipe but not with the stock baffle installed. Removing the baffle in the V&H pipe produced good power from 4000RPM to redline. Inserting a competition baffle with a 2.25" ID brought my usable power range to 3000RPM. The competition baffle made a noticable increase in mid-range torque and eliminated reversion above 3K RPM (no more carb clacking). Experimening with and finding the correct exhaust baffle size for your setup will produce better throttle response, more mid range torque and better fuel mileage without hurting top end power.

I'm very happy with the RS34s on this engine now but it's taken some time to set everything up properly. Now I've got a smooth idle with great midrange and top end. The engine pulls strong in 5th gear from 3K to redline with no bog or hesitation. The RS34 are also very easy to work on and once tuned, they stay tuned.

Hope this is useful.

This is great info.Thanks very much. im sure info like this will be usefull to many who wish to try these carbs.
Can u explain the term Reversion to me please. i am not formiliar with this.
I just put my 1300cc motor in the bike today and i plan on running the 34's on it.It has serious porting and 37.5mm intakes..424" lift cams,Kerker.

Davel - perfect timing for me, just took my first ride today on my totally rebuilt bike with brand new RS 34's. Bad news is they ran terribly. Do you have some set up specs to share? I think it's running lean but I'm shocked it runs so bad.

Do brand new carbs need synched?? It sounds like they are way off...

Damn I wish I wouldn't have sold my 33's until I tried out the new engine, then I would know it's the carbs for sure.

Reversion is when air and fuel enter the intake port from the cylinder. It can happen at the beginning of the intake stroke when the valve just begins to open if there is pressure in the cylinder from the remaining exhaust gas. It can also happen at the end of the intake stroke when the piston is rising in the cylinder but before the intake valve fully closes. Good exhaust scavenging with a properly sized baffle (to maintain velocity through the exhaust) and good intake velocity through the port will greatly reduce or eliminate reversion.

Here's a link I found from Mikuni about flat slide rattle and reversion. It even mentions the affects of open exhaust.
www.mikuni.com/c-faq.html

Mark, your RS34s with a 1300 and .424 lift cams may respond better to larger ports. This is a much more radical combination than mine. My 1075 with .365 lift cams definitely likes smaller ports. I've experimnented with both on this engine.

Regarding adjustment; I've changed needle position and main jet size for different exhaust setups but not drastically. Usually 1 jet size/needle position up or down. I'm currently running the needles at the middle position (factory setting) with 125 mains. Carburation is spot on.

The only issue I've had with the RS34s has been with the accelerator pump rod/spring sticking. Check to make sure your accelerator pump is working.

Thanks .That was a good read .
What methods are u useing to determine wether u have acheived the proper jetting?

79MKII wrote:

Davel - perfect timing for me, just took my first ride today on my totally rebuilt bike with brand new RS 34's. Bad news is they ran terribly. Do you have some set up specs to share? I think it's running lean but I'm shocked it runs so bad.

Do brand new carbs need synched?? It sounds like they are way off...

Damn I wish I wouldn't have sold my 33's until I tried out the new engine, then I would know it's the carbs for sure.

What jets did u have in the vm33's ,and where they running well? What jets do u have in the RS34's,and describe what running terrible means?
What has been modified on the bike?

Mark - I think I sent you my 33 specs a while back - can't remember for sure. I don't have any of the settings with me right now, but the 34's are all stock except for mains (changed to 130 or 140 I think). As far as mods, here's a few: 1260cc, 10.5:1 cr, .425 cams, o/s ss valves, ported head, msd ignition, andrews coils, msd plug wires.

Everything was new from the bare frame up, so I don't know for sure that it's the carburation, but it sure seems like it. Running with my old 33's would have really helped to narrow it down. The bike won't idle unless the choke is on and then it revs to about 5 grand. I rode it yesterday and could barely keep it running unless the choke was on, then it was hard to stop because it revs so high - had to play with the choke the entire time. Seems pretty decent above 5k, but terrible below that. Sounds like it's running on 3 cylinders (but it's not) or the carbs are way out of synch. I'm guessing really lean?? Weird part is the plugs are black:S I couldn't even begin to check the synchronization because of how it's running. Any ideas??

Well if u need the choke id say u are safe to say it is lean.u likely have 17.5 pilots. have u tried to open the fuel screws ? the spec says 1/4 to 1/2 turn max.if it is still lean at 1/2 turn I would try a 22.5 pilot jet next. the suplyed mains are likely 115's so u will need to go up to 130 to 140 mains id say. I'd disconect to pump untill u dial in the jets.