Ok. I have a 2005 Yamaha Grizzly and this is the 2nd time I've started it and it just died for no apparent reason. Now, it won't start back up. The engine turns over, and it is getting plenty of spark. The gas is turned on and it is flowing at the carb float bowl. My suspicion is that the carb float is sticking. Tapping the carburetor with a screwdriver handle fixed the problem the first time but it's not doing much of anything this time. To confirm the float was sticking, I kept the fuel line hooked to the carb and had the gas on. I opened the float bowl drain on the Mikuni carb and nothing is coming out. Would you all concur that my float is sticking? If not, what else could it be? Is there a trick to forcing it open without taking the carb apart? If I have to take the bowl apart, how much work is involved? Is there anything that normally causes it to stick?

 

Is the gas level in the tank low enough, that it needs to be on reserve?
If the float is getting hung up, and sticking, then the shellac is probably to the point that the carb needs cleaning. You could try some carb cleaner stuff in the tank, and that may help.

 

The gas tank is near full.

I'm wondering if this thing needs an inline fuel filter.

 

It doesnt come on it stock, but as long as youre gonna be cleaning the carb, its a piece of cake to add one then. There should be a strainer in the gas petcock, but it would take a lot of crud to block that. But try the reserve position anyway..there could be an obstuction on the regular tube in the gas tank the reserve uses a different pick up tube.
Check the venting of the carb( the rubber tube for draining is also the vent and may be plugged shut with mud), and pull the gas cap off..if the vents are plugged, gas wont flow.

 

It turns out that the needle in the carb had to be replaced. It was seized up due to varnish in the gas. I talked to the dealer about it and they said in order to prevent it, I should add fuel stabilizer into my gas tank. I have to do a little research yet to know if this is true or not but apparently, refining companies claim that gas only has a shelf life of 90 days before it starts to develop deposits on parts with which it comes into contact. While I've heard of varnish forming on carburetor parts, I didn't know it can happen as soon as 90 days.

 

Gas has less shelf-life than in the past....guess we pay more for less

 

Theres an easier and cheaper way. In fact its in the owners manual, but we all forget about it.
When the quad is gonna sit more than a couple of days, drain the float bowl dry.
You can do this one of two ways. Just before you park it, turn the gas valve to off, and drive or use fast idle in park, until it dies. It takes about 40 seconds for the carb to go dry. Or you can shut off the motor, and then use the screw on the bottom of the float bowl to drain the carb...but shut the gas valve to off before doing this.
The reason the deposits build up, is because the gas evaporates and refills the float bowl, and the contant distilling, leaves behind solids, which cause lots of issues. If the float bowl is left dry, there wont be any evaporation (in the carb anyway), and no refilling. When you go to use it next time, flick the gas valve to on, wait a half minute for the float bowl to fill..and itll be ready to go. Usually it is the pilot jet which is the first to show symptoms of shellacing, but if you use this procedure...you wont need to clean the carb again.