I have a sportsman 400 and the guy I got it from says it won't stay in low range, jumps out, any ideas as to what is wrong, in shift box or trans

 

Could be either one,but the older model shift boxes did cause problems. First off make sure the linkage levers are tight on the transmission. Place the shift lever in neutral and loosen the 10mm locking nuts on the linkage rods that secure the rod ends at the shift box. Then remove the two 10mm nuts holding the rod ends to to the shift box levers.(You can test manually at this time by using vice grips to place the transmission in gear and see if it jumps out,which would indicate transmission problems) With the linkage rods removed from the shift box,see if you have a lot of play back in forth on the shift lever while still in neutral. If you do, this could be the problem of jumping out of gear because of not being able to get a positive gear engagement. While still in neutral loosen or tighten the rod ends to where they drop straight into the shift box levers and tighten the lock nuts. Then replace the two 10mm nuts. This aligns the linkage to the transmission. If it didn't jump out of gear when you manually shifted,could be wear in the shift box itself. You didn't say what year model,but all the older ones were basically the same untill the straight line shifters came out.Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse

 

its red and big, I'll find out what year it is and check out the linkage like u said, if its the trans do u have to remove the motor? or can it be worked on the bike? thanks

 

The engine can stay,the transmission has to removed and split if you narrow it down to that.