I am sorry if there is an obvious answer to my question. I just bought a 05 KFX 400 that is completely stock. The tires are original and about 70% worn. It is pulling to the left pretty hard when I am on the throttle. What causes this?? By the way, I have not ridden it much yet. I have a very long driveway that is all concrete. This is where I noticed it pulling. Maybe it won't do it as much in the dirt. I hope someone will know why it is doing this.

 

Mabey bent a arm or ball joints are shot or even low tire pressure? just suggestions hope it helps

 

That is the same problem i am having on my KFX i go to do wheelies and it always pulls to the right for me. I looked at everything nothing seems to be bent but i am think it probably could me the tires pressure so when i get around to it i am going to try that. Let me know if you got your fixed and what the problem was.

 

These things are not made for tar or concrete, so it is tough to figure what might be causing an alignment issues. If it pulls in the dirt or hard-pack youmight have a real problem...

But tire PSI will certainly cause this pull. Also you might not know it, but your body position could be slightly set to one side. On dirt it won't matter, but on concrete it might be enough to cause a pull. I know a guy who was having a similar problem, he would pull wheelies in his driveway (450r) and the quad would always pull left. I told him is butt was hanging to the left on his wheelies, he didn't realize it since it was just how he'd done it for years.

 

Well guys...I hope this helps. My rear tires were worn pretty bad. I went this morning and got some new tires put on the rear, and the problem is gone. I did not check or change the front tires, only the rear. I have no idea why, but new tires on the rear solved the problem. Wheelied in the parking lot at the tire store and the pulling was gone. Thanks...

 

I think js 71 got the right idea. My freind had a z400 with same problem his tires were beat he got news and has no problem. The guy at the dealership were he bought the tires told him if you do donuts and you dont realize you do them the same way all the time that one tires is slighty a little more beat then the other and could cause the pull.