bs34 jet needle

ok I have changed my kz900 over from the 26mm carbs to the bs34mm with 140 mains and 40 pilots.My timing is correct, sparkplugs, wires , coil mod and carbs were cleaned and synched. Now the bike does run pretty well but I still feel these carbs are still not quite right,in fact the 26's were almost equally as good so I'm left to believe in the jet needle which is a single clip (5GN45). My question is should I try to shim this needle for better performance?
I have great top end when I hit aroud 7000rpm but down around 3500 to 5000 its just not that great,also my air/fuel mix screws are 1 3/4 out from lightly seated.I have a kerker with pods as well. Any opinions would be great Thanks All for the tips!

I've heard that people do this. Over on the Buell forum, they use # 4 washers under the head of the needle and they say it makes a big difference in the mid-range. These washers can be found at crafts and hobby stores. One washer measures approximately .050" thick.
If you shim the needle, what is the worst thing that can happen? It might run worse, but if it does, just remove the shims (washers)and you should be back to what you originally had. best of luck, and report back to let us know if it makes a difference.
Grant.

The needle from my BS34s is a 5fl51, factory for my 82 1000. What bike did your carbs come off of.
Tom

I got them off ebay apparently rebuilt.He said they were from a kz1000 police bike but he didnt know what year, they are bs34's. The stamp on the carb is V209 H781. Does anyone have any ideas thanks

The 5GN** is much richer than the 5FL**. These carbs might be way too much for a stock 900 motor with the stock cams. The cams on a stock 900 are only about a 280 lift. The 34CV carbs are equivalent to about a 31mm smoothbore. That is a lot of carb for a low lift 900.

You must realize that the 900 has the same bore as the 750, while the 750 has a much higher cam lift. You would also have to modify the slides or run an airbox to create a greater vacuum. Without proper mods to the carbs you will have a hard time making it run right with stock cams. You would have to install cams with at least 340 lift to create enough vacuum.

well I do plan on doing some work on it this winter but for now as far as carbs go what would be a good starting point?

If you are running pods, you will have to modify the carbs regardless. You are not creating enough vacuum to move the slides properly. This is why you have a lean mid range.

SUDCO.... Under J for Jets....

www.sudco.com/onlinecat33.html#j

OMR

SUDCO unfortunately dose not carry 3mm needles for anything smaller than a 44mm carb. These are for the big twins. This is because Mikuni dose not make them. The only way to get hi performance 3mm needles is to buy a Dynojet kit or to have them made like I do, for the modifications I do on these carbs. Kawasaki no longer sells these needles either, stock or otherwise. I personally do not care for the Dynojet needles, because I think they are much TOO rich. Plus I do not care for their jets. I prefer the Mikuni jets.

So should I try shimming the needle I have now,You were saying it is a very rich needle and this is why I have a lean mid range,I am not sure if I am too rich or too lean please clarify your opinion as to which route I shall go.Thanks for your insight.

You do not have to shim anything. This is not a needle problem this is a slide draw problem. You are not producing enough vacuum to draw up the slides properly and draw the needles up. The reason you are too lean is because the needles are not being puled out the "Needle Jet". This is a "slide" problem. As designed, these carbes are too big for that engine setup. The entire carb will have to be modified,Unless you install a very restrictive airbox.