A clattering noise from the right hand side of the crankcase at idle or during acceleration indicates too much gear lash. A whining noise indicates too little lash. It is a good idea to check main bearing movement before changing gears. This can be done by removing the gear and trying to move the end of the crank. If they are badly worn the bearings will have to be changed. A good rule of thumb for backlash is the higher the primary gear number is the less backlash.

Measure lash by mounting dial gauge as shown in drawing (right). Using long dial gauge tip from snowmobile special tool kit is the best method.
1.	Make sure the dial gauge is firmly mounted.
2.	Hold the primary drive gear stationary at all times.
3.	Set dial gauge shaft at a right angle to the primary drive and driven gear shaft center lines. Set dial gauge tip on a gear tooth side at, or very near, the shaft center line.
4.	Turn driven gear back and forth against drive gear and read lash measurement on dial gauge.
5.	Rotate driven gear and measure lash at (4) points. This procedure will aid in locating any out-of-roundness present in gears or shafts.

1.	If there is too much lash install a drive gear with a higher lash number.
2.	If there is not enough lash install a drive gear with a lower number.
3.	Recheck lash with the new gear installed. Check at least four points and use the tightest measurement.

TX750 Primary Gear lash: .03~.07mm(.001~.003 in.)

PART NUMBER	DESCRIPTION	QTY.	REMARKS
341-16111-00-54	Gear Primary Drive	U.R. 1	Gears must be ordered by lash number. Lower # - more lash Higher # - less lash
341-16111-00-56
341-16111-00-58
341-16111-00-60
341-16111-00-62