Primary Drive Pully
Primary Drive Pulley
Serious warning for everybody - Check the PRIMARY DRIVE PULLEY NUT, it can come loose - as in finger tight.... It can be spun off with fingers, no wrench needed, this is NOT a good thing! This appeared to be an issue with some 2006s.
This is a nut that's supposed to be torqued to 100 ft lbs and staked in place. I hate to think what would happen if it got loose. It's under a cover that's easy to get open to check this, and there's no oil in it - I suggest everyone take a good look at this ASAP.
Its behind the round chrome cover on the left side of the motor just behind the floor board. It has slotted vents, its the front pulley on your drive belt. One note - if you have passenger floorboards, it may need to be removed (or at least one bolt removed to rotate them) to provide adequate space to get the cover off of the primary drive. There isn't much involved in checking it. Six bolts hold the cover on, 4 short and two long (on the bottom). Let the cover hinge down so the wires aren't damaged. The part that is behind the outer cover is the rectifier / voltage regulator (changes AC current to DC and regulates the voltage). According to the service manual the pulley nut is a one time use part as it has the word "new" next to it. I think Yamaha's intent is that if this nut is removed a new one is to be installed in it's place. It takes a 30 mm socket for the pulley nut. Some folks use blue Locktite, torque it to 100 ft lbs then stake the nut. The whole thing takes 15-20 minutes at the most. To "Stake" the nut - There is a groove in the shaft that the nut goes on. The nut itself has a sort of lip on the outer side. You can take a hammer and screw driver and make an indentation in the outer part of the nut to keep it from backing off after tightening it. That part of the nut seemed rather soft so it didn't take much of a tap on the screw driver with the hammer to "stake" it. It may call for a chisel to stake it. I am not sure. I had a screwdriver handy and it worked for the job with just a medium tap to bend the outer side of the nut into the groove of the pulley shaft.
Note from a Star mechanic
I have seen many nuts that were staked but not very deep, these nuts need to be removed and installed with a new nut, Blue Lock-tite and torqued to 100 foot pounds and then staked. The torque is very important!!! Do not just put on with a air impact. When I service all Yamaha twins (1600, 1700, 1900) I have added this to my list, it only takes around 10-15 min's. I have seen 3 nuts that have come off and when they run loose to long the shaft & pulley have to be replaced. When you have your bike in for service or tires tell the service writer you would like the tech to retorque this nut. Piece of mind is priceless!
