picked up a brand new KVF 700 Bought it as is. put all fluids in and started it.
It seems starts easily and idle at the proper RPM, but when you accelerate hard it coughs and runs rough. It will run up rpms but it's breaking up and running poorly. If I open the choke up it runs a lot better.

So I took the air box cover off and it 's got a cracked piece missing about 3 by 3 on the very top. took off the filter assembly and the throttle slides move properly
or so they seem. fuel lines seem fine as well as filter. The plugs look to be alright and compression is fine. This unit has over ten hours on it as I was worried it had a chip that had to burn out like on my snowmobiles but I don't think it has that.
This seems to me to be a carb problem as apposed to spark but I have no experience with these carb's
any Idea's would be greatly appreciated

Zbart

 

Sounds like it's starving for fuel if it runs better with the choke on, try re-jetting it richer. Did it come from a different elevation then where you're trying to run it?

 

what are the chances that broken piece of ( filter box ??? ) fell into the carb ??? I had a machining piece from the gas tank "screw its self into one of my main jets, & it did exacly as you are describing...

 

Well I put all back together and bought a new air box cover and installed that, and all I can say is HOLY F*$# DOES THIS THING ROCK!!!
It was the first time I rode this thing running right and I just pulled it out of the garage and just hit it ....It stood straight up in the air!!!!!! and almost went over


I can't believe that that having a hole in the air box or running this thing without the air box cover makes that much deference in the way it runs, but believe me it does!!

I would believe if this thing is jetted for this much restriction in the intake system , that's there's a lot of performance to be had by working in this area!