16/38 vs 15/40 on my FS550E?

The stock 16/38T sprocket combination results in very tall gearing. Almost impossible to touch 6th gear unless you're doing 80mph.

I've switched over to 15/42T sprockets and it seems to be a good balance for me.

When I got my FS650 it had 16/38 as standard & like supertyreguy said, way tall. Went to 15/38 & could use 6th gear at 70mph/112kph. Now run 15/42 as I'm looking for the grunt to 100kph ( which is our max speed limit just about everywhere :roll: ). Good for power wheelies in 5th to about 120kph which is about as fast as I want to go on the road.
If you've got 15/16 & 38/42 combination you'll be spot on no matter where you're racing. If you swap them over regularly you'll get good life for the initial outlay. You can use the same length chain, just turn your adjusters around.

Just thought I'd throw my two cents in here........ I don't have, nor have ever had an FS model bike, but, I do have some opinions on setting up the final drive. I have been a big fan of using the largest chain wheels you can for some time, as this helps keep the tension on the chain slider on the swing arm to a minimum, and it also extends the chain life as the chain doesn't have to make such a tight bend at the counter shaft sprocket. I do have some asphalt racing experience too.

So, it seems like the hot set up is 15/42 which is a 2.8:1 ratio.

Since your bike came with a 16 counter, why not go to a 45 rear sprocket and this will give you a ratio of 2.81:1. Very close to what supertireguy and wildman are running.

IMHO, if you are trying to set it up for the track that you linked, then you should be just reaching peak revs in 6th at the end of that 1400' back straight. Now is that 1400' straight a true straight or do they have you go through those chicanes? Otherwise it looks like the start straight would be the longest flat out straight.

What do you think?

Right on,

You may end up doing more shifting, but, it comes down to how hard you want it to pull. If it's geared too tall it's not going to accelerate as quickly as it could. I set up my off road bike so that I can use most of the gears most of the time. It's very seldom that I cross a dry lake bed in a full tuck, and need 6th gear to pull me to 110 miles an hour. On my FE550, I am geared 15/52, that gives me a 1st gear that is good for the gnarliest of technical sections, and I can use 6th in the sand washes, and, on a dry lake it will still pull me to 102mph.

I used to race a 250cc shifter kart for 5 years, and I would always set up my gearing so that it would just be topping out in 5th gear at the end of the longest straight. And, now matter where I was at on the track, I had a gear that would pull strong out of each corner.

I ran a 15/50 on my 06 FE550 & no way would I rev it to 100mph/160kph. I did a main bearing in my 06 FE550 wraping it out to 140kmh & letting go of the throttle so not keen to do that again. Especially 15hrs after a rebuild. I now run 15/48 onmy 07 FE550 & whilst I have to fan the clutch a bit in the tight stuff I've still got heaps of revs in the bag on the open bits.

Ran 15/38 on 2002 FS650e when I had it and it was fine. 6th gear was an overdrive for long runs to keep the revs down at speed. Wheelied in every gear still though!

An interesting thread to pick up..
Im going 15/38 on my 550 with 17" supermoto wheels. Currently I have 15/47 in enduro form.
And yes I like them tall. Stock enduro is 15/48 and that is as short as I would want this bike anywhere.
Stock Fs 550 was 16/38. Did I say that right?
Now that sounds very tall.
So I seem to be close at 15/38 for general street use not track racing. If not, I can see going to 15/40.
16/40 is where my Fs 650 is happy.

pollo