Paulwhite Posted October 30, 2010 Share Posted October 30, 2010 hi all im having a hard time trying to think of the final gear ratio i should use for my project. the xvs 125 has a gear ratio of 59/16= 3.6875 (taken from sprocket ratio) but that is to pull the mass amount of weight that the bike has (dont know exactly how heavy it is) and top speed is about 60mph (with me on it and im 10.5 stone) but the bike im building is going to be allot lighter with a little more powerful engine (cbr 125 has a little more torque) so my question is what gear ratio should i go for? with the front sprocket being a 15 tooth and the rear being 59 tooth im gonna get a ratio of 3.93!! which i admit is mint for acceleration but the top end is going to suffer....allot! also anyone know where i could get my hands on a smaller rear sprocket for the xvs 125? say a 49 tooth? or there abouts. cheers. Paul. Link to comment Share on other sites More sharing options...
Moderator mervin Posted October 30, 2010 Moderator Share Posted October 30, 2010 Take a look at this My linkhttp://www.gearingcommander.com/ and this My linkhttp://www.sprocketspecialists.com/SprocketOptimizer2.aspx and JT sprockets do a 56 tooth sprocket My linkhttp://www.jtsprockets.com/52.0.html?&L=0&sel_uid=2211&p= available from wemoto My linkhttp://www.wemoto.com/bikes/Yamaha/XVS_125_Dragstar/00-04/ Link to comment Share on other sites More sharing options...
Reservoir-dog Posted October 30, 2010 Share Posted October 30, 2010 Hi Paul is the cbr engine from a Honda? Anyway the terrain in the the UK is much more flat compare to other regions of Europe or the world. If you were an Albanian or Swiss rider things could be different but as a cruiser in this country I would go for 2 up at the front an 3 down at the back. As you know I did mine 2 up (front) 2 down (back) but I will go for 3 down back if I had to do it all over again. Just an opinion mate. Link to comment Share on other sites More sharing options...
Paulwhite Posted October 30, 2010 Author Share Posted October 30, 2010 Take a look at this My linkhttp://www.gearingcommander.com/ and this My linkhttp://www.sprocketspecialists.com/SprocketOptimizer2.aspx and JT sprockets do a 56 tooth sprocket My linkhttp://www.jtsprockets.com/52.0.html?&L=0&sel_uid=2211&p= available from wemoto My linkhttp://www.wemoto.com/bikes/Yamaha/XVS_125_Dragstar/00-04/ cheers mervin! just what i needed m8 Link to comment Share on other sites More sharing options...
Paulwhite Posted October 30, 2010 Author Share Posted October 30, 2010 Hi Paul is the cbr engine from a Honda? Anyway the terrain in the the UK is much more flat compare to other regions of Europe or the world. If you were an Albanian or Swiss rider things could be different but as a cruiser in this country I would go for 2 up at the front an 3 down at the back. As you know I did mine 2 up (front) 2 down (back) but I will go for 3 down back if I had to do it all over again. Just an opinion mate. yes m8 its the honda cbr 125 (2004) the biggest sprocket size for the engine is 17 teeth and with the smaller rear sprocket the gear ratio would be 3.29 which is better than the 3.9 iv got now lol the problem down my way is its quite hilly so im gonna need some torque to get up them, but want to be able to hit a decent speed. so need to find a happy medium iv done it all back wards and bought a chain and sprocket kit not realizing that the rear sprocket has 59 teeth lol anyone want a brand new 16 tooth front sprocket? for £7? lol Link to comment Share on other sites More sharing options...
Ttaskmaster Posted November 1, 2010 Share Posted November 1, 2010 Unmodded 125 Dragstar weighs 144kg. Link to comment Share on other sites More sharing options...
Paulwhite Posted November 1, 2010 Author Share Posted November 1, 2010 Unmodded 125 Dragstar weighs 144kg. cheers, is that dry weight or with a full tank and oil ? Link to comment Share on other sites More sharing options...
Reservoir-dog Posted November 2, 2010 Share Posted November 2, 2010 cheers, is that dry weight or with a full tank and oil ? Dry weight Paul http://www.bikez.com/motorcycles/yamaha_xvs_125_dragstar_2004.php Link to comment Share on other sites More sharing options...
Paulwhite Posted November 2, 2010 Author Share Posted November 2, 2010 cheers joe Link to comment Share on other sites More sharing options...
Reservoir-dog Posted November 2, 2010 Share Posted November 2, 2010 ;) Link to comment Share on other sites More sharing options...
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