Is my problems Carbs or what??

Hope someone here can help me. I have a 75 900Z1 that I'm in the process of restoring. Problem I'm having is kinda strange. Bike starts fine, idles fine after warm up. When I ride it has good power in first gear but starts stalling from 2nd gear on. If I open the choke bike runs great. Runs a bit better but not great when motor completely warms up. Naturally I have to turn the choke off when I pull up to a stop light or else it dies. Hope someone can be of some help. Thanks

float heights correct?

had a 76 kz650 a few years ago that did something similar. oddly enough if i took the air filter out (and yes i did try a new one) it ran like a scalded dog, but would bog way down and hardly run if the filter was in.

This can be carburetors or bad compression. Do a compression check first. That way you don't have to tear anything apart. If you find the compression OK, check that you have a strong spark. That can also cause these symptoms. If you have a strong spark than tear the carbs apart and do an overhaul. You do not have to pull the slides, just do the lower part of the carbs. Pay special attention to the system (Improperly called the choke) and all the air and fuel jets.

Sounds like you need to pull the carbs and clean them again. It has taken me 4 times before I got them right.

Before you pull anything, do the prescribed checks. It will save you a lot of time in the long-run. These checks will only take you about 15-20 minutes. It will be time well spent and it will give you a decent look at the overall health of the engine.

mastermudd wrote:

had a 76 kz650 a few years ago that did something similar. oddly enough if i took the air filter out (and yes i did try a new one) it ran like a scalded dog, but would bog way down and hardly run if the filter was in.

Symptom with throttle 3/4~wot --- Possibly main jets too large, thereby running better with more air from airbox absent filter, and worse with less air when restricted by filter;

Symptom with throttle at 1/4~3/4 --- Possibly clips on the jet needles are too low (raising needles too high), and resulting in excessively rich mid-range, thereby running better with more air from airbox absent filter, and worse with less air when restricted by filter.

Good Fortune!