pretty simple question, need answer.

i have a kz650 v&h header, i rejetted it to where above 6k, the bike pulls great, but under 6k the bike has a stutter and slug, it has 107.5 main jets, and the needle is 4th clip. if i take the air filter out of the bike, it runs perfectly, should i go one size down on main jet? or should i move my needle clip to stock?

Pulling the filter out and the bike settling down points to an over rich syndrome. Put the needle clip back to the third notch and see if it helps. been working out the running on my '79 Sr with 26mm kz900 carbs, so i have got a bit of recent experience.

u say it stutters under 6000. what u need to focus on , is where the throttle is at the stutter. u need to know if u are at 1/8, 1/4, 1/2,3/4 throtlle . this will tell u where the slide on the carbs are. if the stutter is below 1/4 throtle at cruise, u need to adjust the pilot system(air screws). if it is between 1/4 and 3/4 throttle, it is the needle clip posision. 3/4 to full is the main jet.
u can put some tape around the grip and mark off these positions before a test ride.
Good luck.

Visually inspect your plugs... will inform you also of the running conditions....

Just in case.... How to Read Your Spark Plugs...

kzrider.com/index.php?option=com_docman&...d&gid=460&Itemid=108

OMR

4rugrat1 wrote:

i have a kz650 v&h header, i rejetted it to where above 6k, the bike pulls great, but under 6k the bike has a stutter and slug, it has 107.5 main jets, and the needle is 4th clip. if i take the air filter out of the bike, it runs perfectly, should i go one size down on main jet? or should i move my needle clip to stock?

Return jet needle clip to stock (presumably middle) position, as the jet needle and needle jet largely determine air/fuel mixture during throttle mid-range, where main jet size has very little effect.

Influence of main jet size is mostly at wide open throttle and near WOT.

Jet needle clip position has virtually no influence at WOT, where main jet size and needle jet are controlling mixture, and jet needle is no longer restricting fuel through needle jet.

Good Fortune!

4rugrat1 wrote:

i have a kz650 v&h header, i rejetted it to where above 6k, the bike pulls great, but under 6k the bike has a stutter and slug, it has 107.5 main jets, and the needle is 4th clip. if i take the air filter out of the bike, it runs perfectly, should i go one size down on main jet? or should i move my needle clip to stock?

You still running an airbox? :huh:
Quit wasting that V&H pipe and...

GO BUY SOME PODS SOLDIER !

Mission briefing:

-Aquire four pod filters and crankcase vent filter.
Note:
These pods can be purchased in sets.(K&N makes nice
ones).Attach vent filter to the hose that went to your
airbox,or get a new hose.Ziptie it somewhere high.
Don't mount this small filter right on the crankcase
where it looks so nice,oil will escape.

-Place the clip on middle position.

-Return air/fuel screws to midpoint.

-Dial in the jetting if needed(averge temp day only)
Note:
Expect remove the carbs several times on this mission.
Your 3 targets are as follows.
-pilot jet/air-fuel screws (idle-1/3 throttle)
-Needle (mid throttle)
-Main jet(wide open)

WHY ARE YOU STILL HERE MAGGOT !
EQUIP THAT KZ ,KILL THE ENEMY ! :woohoo:

4rugrat1 wrote:

i have a kz650 v&h header...needle is 4th clip. if i take the air filter out of the bike, it runs perfectly, should i go one size down on main jet? or should i move my needle clip to stock?

Besides returning carbs to oem configuration, would also fit a brand new air filter (if not already done).

Good Fortune!