I'm considering changing my stock transmission pulleys to 30 and 70 from 32 and 66. That will increase the rpm range in 1st by about 600 rpm's. Assuming I apply the same rate of throttle increase will I stay in 1st longer after I change to 30/70 than I currently would? I ask because someone who knows much more than I do about bikes says that with the change to 30/70 I will actually be in 1st for a shorter duration even though I will attain a higher speed in 1st. Thanks.

 

That someone is right you are increasing rpms with this change which means you will be shifting to second quicker.So you are actually going shorter not taller.

 

Thanks, Mark. The way I understand it now is that when you "shorten" the gearing you increase the number of engine rpm's per each revolution of the rear wheel. When you make the gearing "taller" you decrease the engine rpm's per each revolution of the rear wheel. Decreasing the number of teeth on the front transmission pulley "shortens" the gearing and increasing the number of teeth on it makes the gearing "taller". Decreasing the number of teeth on the rear transmission pulley makes the gearing "taller" and increasing the number of teeth on it makes the gearing "shorter". Please correct me if that is wrong for the benefit of others who don't understand the concept.

 

Let me see if I can help or confuse you even more...changing your sprockets (whether you drop teeth on the FRONT or add teeth to the REAR or in your case both) your final drive number goes up ie: lets say stock you're 32 ft 66 rear=2.87... if you change the front to a 30 ft 70 rear=3.23 the gear ratio goes up (taller) B U T as Mark mentioned you do shift sooner. The higher the ratio the sooner you shift (actually shortening the time you have in 1st gear) I believe you are wanting to beat your buddies off the line because they will eventually catch up with you. Now if you are looking for a bike with a high top end speed you do the opposite...make the front sprocket bigger or the rear smaller.

 

My question is does anyone out there know would I have to purchase a new belt if I drop my 13 FLHX from a 32 to a 30 tooth front sprocket?

 

You will have to go one tooth smaller on the belt. General rule of thumb: if you drop one tooth you can keep the stock belt, if you drop 2 teeth you will need to drop one tooth on the belt.

 

you got it.

 

cool thanks