76 kz900 needle adjustment.

I am trying to drop the needle in my 78 kz1000, It is equipped with 76 kz900 carbs, rebuilt and jetted by George. I have done the coil mod, my plugs still get sooty and it's doggy right at the bottom. I was thinking dropping the needle one notch might help. I've never done it though. Any help? Thanks

b]Pro_window78 wrote:[/b]

I am trying to drop the needle in my 78 kz1000, It is equipped with 76 kz900 carbs, rebuilt and jetted by George. I have done the coil mod, my plugs still get sooty and it's doggy right at the bottom. I was thinking dropping the needle one notch might help. I've never done it though. Any help? Thanks

Would be reluctant to immediately change the settings as already determined by wg.

Often, sooty plugs result from something besides the mid-range fuel mixture (largely governed by the needle clip setting). Which imo should be in the middle clip.

Doggy right at the bottom would more likely indicate a possibly too large pilot jet as opposed to needing a leaner jet needle clip setting.

If not already done, would first perform compression test and check/adjust valve clearances, all to assure adequate compression.

Would also visually inspect spark quality, to assure adequate spark.

Also assure correct service fuel level in float bowls via the clear tube test.

Here's an excerpt from the carb info link at Z1E:

26mm (VM26SS) KZ900A4 & A5
Main Jet 115
Air Jet 1.0
Needle Jet O-6
Jet Needle 5DL31-3 (last number is the clip position)
Throttle valve (slide) 1.5mm cutaway
Pilot Jet 17.5
Air Screw setting 1 3/8 turns out

Good Luck!

i thought they were supposed to be plug and play with basic idle adjustment,have you asked wg? the problem with doing too many differant mods at once is its hard to tell which is the problem.

When I check the valve clearances, What should I be looking for?

Pro_window78 wrote:

When I check the valve clearances, What should I be looking for?

Insufficient clearance can cause loss of compression, especially at normal operating temperatures.

This is one reason why cold compression test figures may look okay (valves sealing when cold), but compression is lost as valve sealing fails with increasing engine temperature.

A too tight intake valve may allow backfiring through the carb.

Good Luck!