Insert creative title about gear ratios here...

Sorry about the title of this post everyone. I'm still trying to get back into the blogging saddle following my trip to Mississippi. So then, after outings at two big tracks and a bunch of times at the kart track, one thing became abundantly clear with the little Ninja, I haven't been using the Ninja's full rev range. According to the Ninja 250 Wiki page, the bike has a redline of 15,000 rpm. I have only seen revs around the 13,000 mark on some of the longer straights. I have basically ignored 5th and 6th gear. The bike's stock gearing is supposed to be a 14/44 sprocket combo. I figured it was time to do a quick project to change the way the Ninja powers out of the corners. 

Here we are at the business end of the matter. After a bunch of hours on the Ninjette forum trying to get an idea of how best to do this, I decided on dropping down one tooth in the front. Dropping down to a 13 tooth counter shaft sprocket changes the drive ratio from 3.14:1 to a 3.38:1. This change won't give me lightning fast acceleration, but it will help me keep the revs up higher in the Ninja's power band and I should feel a bit more torque coming out of the tight corners of the kart track or a technical track like the Streets of Willow. In the end I may have to shift more as the bike will rev out sooner than with the OEM final drive ratio.

To do the swap, I first pulled off the shift lever connector from the rear sets and removed the three bolts of the counter shaft sprocket cover to expose the front sprocket. I then removed the two bolts holding the sprocket retainer on and was able to slip the sprocket off the shaft and out of the chain. I didn't have to loosen the rear wheel adjusters or rear axle, though I did later as changing the counter shaft sprocket ends up changing the chain tension.

The new front sprocket went on just as easily as the old one came off and the whole process was reversed. I then re-adjusted the chain tension while trying to keep the rear wheel aligned which is harder than it sounds with this little bike. Every time I have adjusted the chain before now never quite worked out right. The wheel would always end up cock-eyed pointing the front of the rear tire to the right of the bike. This happened even when I would use my chain alignment tool on the bike. It was if the chain was too short. I looked up the OEM chain length and counted the links only to confirm that the chain was the correct one for my needs. Odd...

While I had both sprockets off the bike I took this shot to show the difference between the two. A keen eyed observer will notice that the old sprocket is a 16 tooth and not a 14 tooth. That is why I had so much trouble with chain tension and alignment! One of the previous owners put on a +2 16 tooth front sprocket, probably to get better commuting mileage by dropping the revs for freeway stints. By going down 3 teeth to the 13 tooth countershaft sprocket, I will really feel the difference on my corner exits and straight-line acceleration. My new final drive ratio change will change from a 2.75:1 to the aforementioned 3.38:1 making me wonder if I'll be able to keep the front wheel on the ground?

I won't be able to test the change for a while. Maybe I'll get out to the kart track after my move later this month. I'm really interested the difference this project gives me. I expect that the ride at the kart track will be very different. Hopefully my lap times will drop. I know I'm going to have to reprogram my brain for new shift reference points. Fun stuff!

Well I have a few more projects going on concurrently as I prepare for my transfer and move. I need to button them all up so nothing gets forgotten in the hustle. Come on around very soon for more My Motorbike Obsessions action.

Blue