Flat spot need help (new info) and pics

Im running BS34s and they run good but for a flat spot from around 6000 to 7000 rpm, where do I start? I am trying to learn to work on carbs but dont know poo at this point.
Thanks for any help
Tom

That's in the zone where the main jets are doing all the work.

thomas ed wrote:

Im running BS34s and they run good but for a flat spot from around 6000 to 7000 rpm, where do I start? I am trying to learn to work on carbs but dont know poo at this point.
Thanks for any help
Tom

On the large fours, am thinking 6000~7000 rpm is still within mid-range carb function, influenced by jet needle clip position, slide position and cutaway design.

Plug reading may help determine whether fuel mixture is an issue in mid-range. Flat spot might result from either too rich or too lean clip position. Are different clip positions available? If only a single clip position, has it been enrichened by a small washer added under the clip? If so, perhaps the mid-range is too rich.

At 6000~7000 rpm, I would in this instance suspect the jet needle clip position as cause of the flat spot, and not the main jet size.

I don't know whether different size needle jets are available for this carb. Sometimes the corresponding Canadian model carb has a different jet needle (perhaps smaller taper) and/or a different needle jet (perhaps larger orifice) and/or several different clip positions.

The U.S. model carbs were sometimes less subject to "tuning" due to restrictive EPA regulations.

Good Luck!

I will pull the bowls this weekend and look at the needle and see if there is any different clip positions. If not a washer would richen the mixture?
As far as checking the plugs, should I cut the engine off in that rpm range and look at them then? Sounds rite to me.
Thanks
Tom

Pulling the bowls will not do you any good. You will have to remove the diaphragm covers to get to the needles. Also, your carbs should have a fixed clip position, unless someone installed aftermarket needles. If these carbs have a stage kit installed in them than changing the clip position will not help. If these are stock needles than that might be your problem. If these are stock unmodified slides than that might be your problem also. First what you have to know and reveal to us is what you have and what has been done to them. EXACTLY, don't guess. Otherwise it is very hard to help you. Without knowing exactly, than WE have to guess. Going larger than a 147.5 or 152.5 Jet (Mikuni) is a waste and unnecessary. If you are running a headerpipe and pods than that is where you should be as far as main jet size. Than you have to have needles that can handle jets that size and the slides have to respond properly to pull the needles at the correct rate. If all of these factors are not addressed than you are wasting your time.

1982 KZ 1000 LTD
K&N pods
J cams
Vance&Hines pipe
dyna coils and wires
WG rebuilt and jetted my carbs

From the carb guy
I believe we reused the OEM jet needles, used #140 main jets and #40 pilot
jets.

OK that is a start. What exactly did WG do to the carbs? Did he install a Stage kit? When you reach the flat spot, what helps, opening the throttle more or backing off a bit? I personally think that WG should be responsible for these carbs. He certainly takes long enough to work on them and he charges enough!

Notice that WG has not chimed in once to help you here. He leaves it up to you and the membership to clean up his messes. This is getting very frustrating.

First I not trying to bash WG.
I paid him to rebuild and jet the carbs for pods and the pipe. As far as what helps for the flat spot I just throttle through it, its not like it dosnt pull at all it just really comes on at 7000.

I just hit WGs profile and noticed that he last came on line 34 days ago. There are a lot of members disheartened with him.

thomas ed wrote:

First I not trying to bash WG.
I paid him to rebuild and jet the carbs for pods and the pipe. As far as what helps for the flat spot I just throttle through it, its not like it dosnt pull at all it just really comes on at 7000.

OK than this means that the main jet is most likely good. It is a needle or slide problem. Now you have to find out what you have.

The needle and slides are stock as far as I know. What should I be looking for?