banshee67 Posted July 28, 2010 Report Share Posted July 28, 2010 well a couple things. what is the difference between straight cut and stock? and also is there any power or performance vs price gain? Quote Link to comment Share on other sites More sharing options...
J-Madd Posted July 28, 2010 Report Share Posted July 28, 2010 Stock primary gears are helical cut. They mesh at an angle. They are quieter than the straight cuts. Straight cuts can make an unwanted whining sound that is undesirable to the mfg (Yamaha). No need for straight cuts on most motors - I'd say up to maybe 120 hp or so; but they don't hurt anything. The straight cuts help reduce side load on the crank. As helical gears mesh, they pull on the crank (or maybe push?) This robs a tad bit of hp (some say 2 - 4 hp) and is undesirable to the crank and probably crank bearings. Not worth the money unless you've already done every other mod possible to the motor, imo. Quote Link to comment Share on other sites More sharing options...
shanYE west Posted July 28, 2010 Report Share Posted July 28, 2010 helical gears pull the crank to the PTO side with the higher HP machines.. not needed in most apps.. Like J said. they're has been rumors of a few HP gained.. I doubt that anyone has actually compared helical to straight on a dyno for a true side by side. Quote Link to comment Share on other sites More sharing options...
BANSHEE HP Posted July 28, 2010 Report Share Posted July 28, 2010 I doubt that anyone has actually compared helical to straight on a dyno for a true side by side. i have didnt notice any hp gains Quote Link to comment Share on other sites More sharing options...
shanYE west Posted July 29, 2010 Report Share Posted July 29, 2010 I doubt that anyone has actually compared helical to straight on a dyno for a true side by side. i have didnt notice any hp gains Bill.. you got too much time on your hands.. lol Quote Link to comment Share on other sites More sharing options...
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