im having an issue with my ATV when I go to take off it wants to jerk and jump at first but once it's moving it's fine I can't figure out what's going on can any help me diagnose my issue. I have a 2000 model Yamaha kodiak 4x4 semi automatic

 

Could be a host of things, sticking brake shoes or pads, worn swinging arm bearings, worn splines in prop shaft or axle, or a universal joint worn. If it doesn't do it in 4WD, I would suspect a rear axle or rear prop shaft problem.

 

My 4 wheeler is all the time 4x4 and I welded my rear end up solid

 

Not familiar with that model, but does it have a drive belt? I had a 1996 Polaris Sportsman that did that, it was a bad drive belt. Belt actually broke the housing behind it.

 

No it has a drive shaft

 

No it has a belt. If yiour new to it you need to put the foot brake on then shift the gear shift into Hi. I then before letting the brake off give the throttle a small flip and you'll probably here a little click where things are all going into place. Take off.

 

To my knowledge I don't have a belt I have had it torn down and never seen a belt were would it be located
my drive shaft comes right off the back end of the transmission is there a belt in between the motor and transmission that I don't know about. I have had this 4 wheeler for about 3 years now and I have never had an issue up until I busted my rear end but I fixed it and about 6 months later I'm having this issue.

 

I didn't think the 2000 Kodiak was belt drive, but on checking the parts books, it is. I suspect your machine is earlier, as I think the belt drive autos were all switchable 4WD, even some of the late manual gearbox ones were. Do you have a 5 speed foot change gearbox or a fully auto transmission? If it is auto, it is belt drive.