carb clean up
 

The 2000 600 grizzly I recently purchased with only 605 miles would not idle and seemed to exhibit issues with old fuel and dirty carb internals. I have removed and cleaned up the carb with the existing parts due to the low miles. Before I began this exercise, the choke did not seem to do anything noticeable - maybe a 100 rpm increase at best. After cleaning the carb and resetting the float, the bike ran very well. The choke worked as expected with a noticeable 200+/- rpm increase. I was happy. Today is a different story, the atv runs and idles as it should but, the second I move the choke lever, it quits. I don't understand what could have changed or why this is happening in the first place. Being an enrichment type choke, it should only increase the rpm with the added fuel. There is no adjustment available with this setup, it is what it is after the linkage and valve are back in place. Why is it killing the engine ??? And nothing touched overnight! What am I missing? Any thoughts appreciated.

How well did you clean the fuel tank? Did you put an inline filter in?

I cleaned the tank out quite well I think and I added an inline filter.

Is there 3 jets in that carb like the big bear 400's? I had the jets switched one time and caused issues. Or maybe the O ring got pinched or rolled when putting choke back in.

Ok guys, it is a weird situation. Maybe! This morning after a low of maybe 42 degrees, I set the choke and started the bike. It started and ran at an elevated rpm aTurn off the choje and it starts and runs at normal idle for the rest of the day. Once the choke shuts down the engine, it is impossible to move it even a miniscule (0.00001in) while the engine is running. The engine is killed immediately. It is hard to explain and even harder to understand in person. I have a biker buddy watching and witnessing all of this and he cannot explain or understand it either. I guess I will just run with it..

I didn't take it that far apart. I had the pilot screw out, the needle jet and the float valve out. I just blew carb cleaner and air thru the rest of the jets and orifices. I didn't want to damage the rubber washers/o-rings. All parts are original. I had to adjust the float level about 1/8". Maybe that has something to do with it. I do know that it is getting way better mpg now than it was before the cleaning. Maybe I should just get a rebuild kit and see if that cures anything.

if you didn't pull the jets out you didn't clean the carb. Don't 1/2 ass on the carb clean. Do it right.

I ended up getting a carb kit and replaced jets and float needle. The problem was a missing washer and o-ring on the pilot air needle jet. All is now as good as new.