I just bought a brand new Yamaha ATTAK fuel-injected 4-stroke. Nowhere does it specify what changes (if any) need to be made to use it out west at higher elevation. Do you know what I need to do so it runs right when I go to the Black Hills or West Yellowstone?
With the new fuel-injection system, there are no changes that need to be made in terms of fuel delivery. However, as the elevation increases the power output decreases, so changes must be made to the drivetrain to compensate; you will need lighter flyweights and lower gearing.
Your Yamaha dealer should be able to provide you with a set-up sheet that details all of the changes Yamaha specifies for various elevations. The ATTAK calls for lighter rivets in the flyweights (you can swap rivets back and forth or just buy a spare set of flyweights) and smaller upper sprocket in the chaincase, along with a shorter chain. The exact rivet configuration and gearing is dependent on the target elevation, so refer to the chart provided to you by your dealer. There are no changes to the secondary, no spring changes or helix changes at all. About all you really need is some rivets, a gear and a chain. The conversion shouldnâ€™t take much more than an hour or so.