I'm working on a buddies 350 raptor. It will not idle with the choke all the way off. With the choke on part of the way it idles fine but kindof fast. I was just wondering if there is an idle mixture screw somewhere. I can't find one. Could the intake boot be leaking or the diaphram in the top of the carb be leaking? Would they cause these symptoms.

 

On the bottom of the carb near the cyl side there is a screw, it's inside a small cylinder shape opening...this is your pilot mixture screw. The intake boot should be ok as long as you know it's on properly and tight. Also make sure the air filter is clean and the fuel is fresh. If these don't help you might have to dig into the carb and clean it.

 

I think that it's the intake boot between the carb and the jug. When it's idling and it starts to get rough, I spray a little bit of starting fluid on the boot and it smooths out. That makes me think that the boot is leaking. Do you still think that the pilot jet could be plugged up?

 

That jet can be blocked knowing how small it is, the hole goes through to the intake tube above it. You can unscrew it all the way and spray some carb cleaner into it and see if it comes out the top. For the boot I would remove it and see if it is seated properly if someone has removed it previously before buying a new one, they have to be tight in order to keep the seal. If that doesn't help remove it and check for cracks around the rims and order a new one if necessary.

 

I checked the boot for cracks and didn't see any. I'm not understanding why the starting fluid makes it smooth out if it's the carb acting up. I know that if I spray the starting fluid into the back of the carb(airbox side), it starts idling really rough.

 

The carb need's to be removed and cleaned out and probally rebuilt , if nothing else a good cleang and adjustment ; if this help try adding some seafoam to your gas in the tank ! follow thre the instructions on the can for mixing , Seafoam is a fuel cleaner/stabilizer that will help keep the fuel system clean and combuston chamber clear of carbon deposits ! You can get the seafoam from O'Reilly Auto Parts for $5.99 + tax , you should get a good service and repair manual ; it will pay for itself on your first repair ! williebee