What in the world are you hauling to have to be WOT for 75MPH?
Im 170. WOT for me is 94.
You would go down in back up in front for more top speed lower rPms
Mine will pull redline in top 171kph but takes a big effort to get there.
It indicates 162kph on a flat road in good warm still conditons.
On the track I'm getting flatout in 5th but the straight is short.
Going to try a non Oring chain to release a couple lost hp.
That combined with a 39T or 40Twill be about the best setup.
Rusty, Do you have top speeds for these gearing setups?Right out of the gate, I'd like to say gearing lower didn't do anything to the fuel economy. No loss. No gain. Here's my review of the setups I've tried...
14/38 (stock): Peak HP @ 85mph. 68mpg. Mild ride. Very little 6th gear torque.
13/38 (-1F): Peak HP @ 80mph. 68mpg. General/practical. Adequate 6th gear torque.
13/40 (-1/+2): Peak HP @ 75mph, 68mpg. Assertive ride. Useful 6th gear torque.
My personal preference is -1/+2.
With the stock gearing I top out in the mid 80s rolling on 6th. If redlining 5 and shifting to 6th I can get into the 90s, or just going down hill. Close to 100, she's a little unstable.You can plug the values into gearingcommander.com to get the values you want. Just change the "peak power" RPM to 10,500 (red line) since that's the RPM it uses in most of the calculations. For reference, 6th gear red line for -1/+2 is 93mph if I remember correctly.
Keep in mind how much wind drag affects small engine bikes. Gearing taller could slow you down if you can't tuck tight enough. I have a higher top speed with -1/+2 than I did stock, all though at a much higher RPM. I couldn't get stock past 80mph. Evidently I'm a natural wind sock. Some of the guys on this forum are awesome and hit almost 100mph. Your results may vary. I just geared mine to maximize rear-wheel torque for the speeds I use.
Best of luck. Re-gearing makes a big difference.
Brent701 - I live in Arizona also and have put more then 4,000 FREEWAY miles on my CBR250R in the last 4 months. I weight 195 and ride on I-10 the 101 and the 202 4 times a week and have never needed to go above 75 mph. Any time I have needed more speed to pass in traffic I usually down shift into 5th. I have had my CBR250R in the 90 mph range on flat road with a bit of distance to get there. If you find your self with people trying to pass you let them by. You do not have to be the fastest person on the freeway. All you are doing is racing to a possible early grave. Use your head and not your ego.my 195 lb ass.
traffic flys at 75-80 MPH. If i stay under it's almost death.. Well on the freeways here. So I try to stay at 75 in the Carpool lane but most the time I find it wide open to keep it at 75
Part 1: If you're getting that high of a top speed, you're one of the ones who does a good job getting out of the wind's way, haha. My 6th gear roll on topped at 80mph stock. That was because of me though.With the stock gearing I top out in the mid 80s rolling on 6th. If redlining 5 and shifting to 6th I can get into the 90s, or just going down hill. Close to 100, she's a little unstable.
Since you can hit a higher top speed with -1/+2, but with a much higher RPM are you worried about long term effects to the engine?
I would have thought that gearing that tops out the horsepower at 75 instead of 85 would decrease the top speed. Or is torque needed more at top speed because of wind resistance?