Mikuni RS34 Needle size and carb tuning on a 1260

I finally got my bike running and riding this weekend. The carbs need some tuning though. They are RS34's that I bought used, but were only around a year old. They have 17.5 pilots and 125 mains. The needle is a 9dzh5-50. Is this the stock needle size? I was doing some research and came up with a 9dzh01 as being the standard needle. Anyway the bike only runs with the mixture screws out 1.5 turns, and looks like they are supposed to be 1/8 to 1/4 out, so I suppose a larger pilot jet, or raising the needle or changing the needle. Carbs are sync'd with gauges and I got them really close. After around 1/4 throttle it starts to really pull. I didn't rev it very high since I just got the engine together. It's an 8:1 1260, with stock sized S/S valve, mild porting, engle K13 cams. Just curious if anyone has any info on the needle, and if anyone is running a similar combo and the jetting you used.
thanks alot

My set up.....what are running setup wise?

1075 KZ 1000
.395 lift web cams
stage 2 port head
RS 34
pods
4 to 1

I have 34's on my bike. I just had bike dyno tunned last weekend. Im running 17.5 pilots at a 1/4 turn and 125 mains. My needle is a 9DZH1 its in the 3 slot or standard. I dont think the needle is your problem. The needle jet is a stock P-4 These all came stock from Mikuni. I had to change nothing and are stock carbs.

The accelerator pump system is very important on the 34's. This is where all my tune came from. The accel pump was orignaly set to start at 1/2 throttle to 3/4 throttle......it was changed to before 1/8 throttle to after 3/4 throttle.....it woke the engine up 100% and went from a fast ride to an insane ride. I cant beleve the difference in throttle responce and low end bump. You need to understand this system and tweek on it.

You might be able to bump your mains to 130...but would be the last thing I would do.

If you find that the pilot mixture screw is way out....this is not a bad thing. You have more room to adjust a lean or rich condition. If you set the acc pump rod to come on sooner...you will be able to lean the mixture screw abit. I was able to go from 1 1/4 on mixture screw to 1/4 with adjustment of accl pump rod.

Good Luck

thanks for the info, I will check out the accl. pump. So I am thinking the 9dzh5-50 is a richer needle than a 9dzh1. How much power did your bike make?

vintagerider wrote: thanks for the info, I will check out the accl. pump. So I am thinking the 9dzh5-50 is a richer needle than a 9dzh1. How much power did your bike make?

Mikuni USA sends all there RS34 tech support questions to Sudco.

If you want to talk to a person about a richer needle, I would call Sudco.

www.sudco.com/

Just wanted to give an update. The 9dzh5-50 is the same needle as a 9dzh1 according to tech support from sudco. So I raised it one notch, and went to a 22.5 pilot, also adjusted the accel pump to start almost immedietely. Took the bike out today and it ran a whole lot better, not perfect, but much better, still at 1 turn out on the mix screw, plus it was around 35 degrees when I rode it, so in the summer weather it should be even better since it won't require as much fuel in the warm weather. One thing I can't figure out is the overflows still keep dripping. I've cleaned the needle and seat really well, and set the float height with a clear hose off the drain plugs, and I have them all set right where they should be when sitting level in a vice, but after I run it and look at the overflows all of them have a drip ready to drop from the hose, is this common on these carbs? Otherwise I will just replace all 4 needle and seats and be done with it. Thanks for the help.

The accel pump rod adjust is important on the 34's glad your getting closer on tune.

The more pilot you start with...the more you should be able to close or lean the fuel mixture screw. If you smell exhaust....does it smell rich?

Did you talk with Chad at Sudco?

On the drip...I would think float level....does it drip all the time or just after a ride and after sitting? If it does it after sitting....needles and seats may be worn letting fuel past and overflowing the bowls.

when running does it stop leaking?

they drip a little after a ride and sitting for a minute or two and if it sits with the fuel on they will slowly drip a little. I'm going to get new needles and seats. I want to take it for a ride this weekend, when it warms up before I do anymore changes with jetting. Otherwise I am going to go with a richer needle in the middle groove and a 25 pilot, seems like this engine likes fuel. It doesn't smoke at all and it doesn't smell rich at all either, and yes it was Chad that gave me the info.
thanks

Ya, sounds like the needle and seat need replaced.

125 on main still bugs me and sounds light, my setup was correct dead on at a 125 main on the dyno. You have over 215cc of engine bore and air moving though engine, I would ask chad or bump this up to 130 or more.

Do you live in a hot weather area? If you do....you dont want a lean tune. A 1260 air cooled Kawasaki in a hot climate is asking for trouble to start with. A lean tune will run hotter than a slightly rich setup and compound the issue.

Do you run an oil cooler? with the 1260cc engine I would seriously consider it.

Yes I do live in a hot weather area, during the summer anyway. So that's why I used turbo pistons with 8:1 compression and with the cams figured it would keep it somewhat cool. I did put a decent size oil cooler on as well without a thermostat, so we'll see. I'll probably end up with a 130 or 135 main as well, didn't give it full throttle yet, figured I would put some light break in miles on it first.