What is your goals? What has been done and what are you going to do with it? Any experience with carbs?
I built a mild modded Warrior with the stock carb and it was extremely snappy and performed great. Did the usual "o-ring" mod and dialed it in. Getting good parts and using a factory carb is key. Any aftermarket replacement carb has varying issues with quality. Rebuild the factory carb and don't use a cheaper replacement. I found just a soak and spray cleaning didn't get into the circuits enough and had to boil it.
I then wanted to be able to dial it in more and got a FCR 37mm from a YZ250F/YZ450F for my Raptor 350. It's a bigger learning curve if you don't have alot of carburetor experience.
I think a good FCR MX is much better, but I have a lot of time and ordering parts to get it right. I got my best advice on tuning it from ThumperTalk. Search them if you do use a different carb, they have a ton of info on it.
I went with the FCR because I had a partout bike with one. I cleaned it, realized I needed way too many parts, got another one on eBay with aftermarket goodies on it, and sold the one I had.
This place is the best for Keihin parts.
https://www.keihin-fcr.com/index.php?route=common/home if you go that route.
I met the owner, he seemed super nice. Knocked off some of the price because I drove to meet him for the parts with cash. And answered a few questions I had. Also has almost all factory keihin parts.
BTW, the FCR does not directly fit a Raptor 350. Had to dimple the bottom of my fuel tank to fit it. Will fit a Warrior just fine.
DRW sells a nice intake adaptor for a good price.
https://drwperformanceatv.com/index.php?route=product/product&path=59_90&product_id=253
I'm not using it. I didn't find it till after I machined my own.
Also want to add use ethanol free fuel if you can. Also called REC fuel in some areas. Helps with build up in carbs. Use a decent additive if your going to store it for a while.
