Here´s a pic of the neutral finder mechanism on a 650 (79 D2 engine). The mechanism consists of three little steel balls, on the 650 the they are located inside the fourth gear on the output shaft. Inside the gear there are 6 holes (bottom of pic) - three of the holes go straight through but the other three (120 apart) are smaller at one end, these are where the balls go.
In the output shaft where the fourth gear sits there are three recesses app. 3/4" long also 120 apart (one can be seen in the pic). When the bike is not rolling the output shaft isn´t rotating and at least one of the balls drops in it´s recess and limits the gears travel to first and neutral. Once the shaft starts spinning the balls are slung out and you can shift up.
When reinstalling the fourth gear and balls obviously the holes holding the balls should align with the recesses in the output shaft or the neutral finder won´t work.
Post edited by: OnkelB, at: 2006/09/10 18:53