quad jumping sideways

[kfx400rider]

A buddy of mine has an 03 z the carrier bearings went bad and it started jumping sideways at wot.
He got the bearings fixed and the problem is still there.
We are starting to think maybe its his tires.
They are itp xct 22x11x9 holeshots. Has anyone seen a problem like this before.:eek2:

We have checked the axle and everthing seems to be strait and running true. All of the the tires have equal pressure in them.

This is happening while in 4th or 5th gear going straight at on paved or dirt surfaces.

[awj8074]

those are the same tires i have on my 450r and it dosent jump sideways. Is the swingarm twisted?

[Yotapndr*84]

Another thing to check may be your tire pressures. I have noticed on mine if you are as little as 1/2 a pound off from left to right on the front or rear this can happen. Also on the stock Z400 swing arm make sure that the alignment marks on the chain adjustment are even and the axle has not moved. Also check the pivot bearing and bolt for the swing arm. The bolt has been known to bend. Good luck.

[300WheelyKing]

you also might want to check the wheels and see if you have bent one slightly

[2StrokeFreak]

When I first got my 20" xcr's they had 5psi in them. At wide open 4th-5th gear the rear end would pitch sideways, then snap straight before you knew what happened.
Dropped the air pressure down to 3 to 3.5 psi. and that made the differance. Very stable at speed. I believe they are 6-ply tires, dont have to run alot of pressure.

[redrunner]

Have you checked the rear end alignment since installing them. Measure from axle to foot peg on both sides, obviously they should be the same distance.