First off I want to say hello and thank you to all of the people on here that help others.
So as the title says I’m working on an arctic cat that bogs and pops above half throttle under load. It has a new carb (eBay) and a fresh top end rebuild (due to low compression). I have gone through the carb multiple times (carb clean, shop air, and needles through all jet holes) but the problem stills persists (this was a problem even before the rebuild). If you choke the machine it does pick up and run better but not as good as it should. This makes me think main jet but I don’t see how after all the cleanings.
Also this isn’t my first rodeo, I’ve been working on vehicles and small engines for around 7 years and I’m currently a mechanic at a shop in town.
But this has me stumped. Any ideas would be appreciated!

 

Is the ebay carb an own carb or a Chinese copy?
compression after rebuild?

 

I’m pretty sure it’s a Chinese copy but I have compared jets and they seem to be the same. I have not checked compression after rebuild but I will tomorrow.

 

Not only the jets, most of those carbs are not properly set up or they use mismatched parts. They are a real crapshoot as to getting one that works. Spark should be a blue color, yellow means a weak spark. Compression is everything, needs to be over 110, this will also show if valve timming is on.

 

I agree on the eBay carb. I may swap back to the original carb to see what happens. I’ll check spark and compression tomorrow and let you know. It’s probably something simple but multiple heads are always better than one. Thanks for your help!

 

Alright so I checked compression and it is right at about 110 but it does have a compression release so that would be limiting it during cranking. I checked spark (new plug) and it seems blue but the actual spark is very small so I’m starting to think maybe the coil is going bad.

 

Alright so I have narrowed it down to the carb. Funny story. I had my old bayou in the shop that I gave to my neighbors kid for a carb clean. I noticed the carb looked the same as the arctic cat’s so I figured what did I have to lose. I put it on and what do you know it ran great, no popping/bogging. So I swapped some stuff out of the eBay carb into the carb that was originally on the cat and put it back on. Same thing as before. So I guess I’m back to square one, and needing a carburetor. So what do you guys recommend for a carburetor?

 

So after beating my head against the wall lol I finally fixed it. The problem only occurred over half throttle so I knew it had to be the main jet. So I took a torch tip cleaner and made the hole in the jet bigger. I reassembled the carb and the fourwheeler ran like a brand new one. Also make sure you know how the choke works. When the little barrel is blocking air (all the way into the carb) it’s choked and when the barrel is letting air through (pulled back to allow air flow) it’s unchoked.
Many of these threads have helped me so maybe this one will help someone someday.

 

Glad for you that you figured it out. This makes the rest of us remember to always back track on "new" parts. Good job!