By stumble, I mean it stays running, just sputters, not smooth. Cut out means it stalled on me, quit running. I live about 700 feet above sea level, and jet needle is not shimmed. But with stock jet (125) it still had problems. Do you only shim needle with bigger jet? I figure if it makes it run better, stay with stock. I switched it back to stock and had same problems. So now it has 130 jet (unshimmed) again. This guy reworked a snowmobile carb for me and it has been good ever since. Ive had him do other work with good results. But maybe he miossed something. I will take him my manual and some suggestions.

I can run...definitely lean though...stock jets with the Z1 mod and no snorkel, in Chicago. Chicago is a few hundred feet above Sea Level...like you. No stumbling, etc.

Try something really simple: AFTER THE BIKE IS THOROUGHLY WARMED UP, quickly stop and pull off your air-filter cover (3 Philips screws) and go for a quick run. Does the stumbling go away? If so, you're running too rich for some reason (with the cover on)...and we can further plan what to do from there.

Alexd

Just to be sure... the Z1 mod is.. 130 jet, uni air filter, snorkle removed, 1 inch hole drilled in exhaust? My only varients, I have a 1/2 inch hole in exhaust, and cut snorkle in half, with 1/2 inch holes drilled in remaining half of snorkle. I can easily remove snorkle and make exhaust hole larger. Will it make that much difference? Im willing to try anything!

The Z1 mod refers only to the exhaust. I'm a bit confused as to whether you meant ALL of the things that aren't stock on your bike, being the Z1 mod...it isn't.

My OPINION is that #130 main may in many cases be too rich. Perhaps that and a high fuel level in your floatbowl is giving you an overly rich condition. My idea of removing the air-box cover as an experiment, will show whether I'm on the right track or not.

Be very sure the bike is thoroughly warmed up before you do this, or the test will have other variables we don't want.

Alexd

As to the snorkel...I've always just removed mine completely. My GUESS is that what you've done isn't very far away from the same effect; the effect being to allow more air to flow, which ironically works against the theory that your bike is running rich.

Alexd