Stock for stock I won't argue the mathematical fact of gear ratios at all. You are correct, but the OP wasn't concerned about red light to red light running at all. So for his first post of the subject a 6 speed is nothing, but hype. Just my .02/opinion and we all know what those are like........

 

Oh but put a OD6 with this pulley and you have a pull like a mother, pull up 6th for a freeway to leave the mother where your left her, best of both worlds. Ran this combo with the 89"

Currently running 3.34, Baker OD6, 32 Evolution Performance chrome molly pulley that shaved 4 lbs rotating mass with a 127" no complaints, the Baker has the bagger first gear and works well on just releasing the clutch and go, no riding it. 5th gear is 2500 @ 55 mph and in the wheel house of hold on, 6th drops around 2200-2300, run the interstates @ 65-70 and the R's are in a range to get out of trouble without dropping a gear. Another gear can open up alot of versatility so I'm a fan of a 6 speed

 

I love the Baker DD6 in my Evo Road King.

Great acceleration off the line in the first 3 gears and at the same time it levels out nicely when I hit the interstate (75 MPH speed limit). The lower ratio in gears 1-5 give the old 80 incher more pep vs. stock. Probably keeps me from going with a stage 1 which would really **** off my MM FI and the stupid 96' ECM.

 

Actually, the sprocket change was brought up and my response was I didn't want to sacrifice low end power. Traffic where I'm at can sometimes hit close to 90 m.p.h. (yep, I've seen it.) I also like to run at higher speeds on the freeway. I have heard that if you run above 80 for extended periods of time you run a good risk of losing the bottom end in the motor. Running across south Dakota I tend to really crank her up.

 

Yea further down from your original post.

When on a the highway I tend to stay between 80-90 myself.

 

No it won't! I ran my TC88 for several years with a 21T compensator and around 20mph/1,000rpm. Made for a wonderful ride, like Harleys used to be - roll on in top gear was brilliant, happy as Larry at 90mph.

Now I'm envious........

 

Is that with an hd evo? How many miles do you have on it?

 

Head work, cam, ect 80". Motor had 75k miles when taken apart this time. The only reason I tore it down was due to a cracked frame. So I ended up rebuilding the entire bike and stroked the motor. When I tore the lower end down the only thing wrong with the rotating assembly was the rear cylinder wrist pin bushing had spun.

 

thanks for making me chuckle the only car on the market that claims it has double overdrive is the mx-5 but its really not. most cars from the late 80's
till now use this. its called lockup torque converter when your car is in overdrive and your holding a speed the computer tells the transmission to lock the converter.


and as far as mpg the only way you gain is if you have the power to hold the speed and most Harleys don't.
my buddies chopper is similar to mine except for the engine we both have baker OD6 transmissions his bike has around 72 hp and gets 39 mpg my bike has over 100 hp and im getting around 50 mpg. my bike will hold 65 just barely cracking the throttle. at around 2900 rpm

 

Sorry, but you're wrong on your first point. I've been driving a double overdrive T56 for 12 years and they came out in 1997. The 6 speed automatic with double overdrive came out in 2006. The new Vette has a 7 speed manual with double OD and next year, an 8 speed automatic.

Here are the ratios:
http://en.wikipedia.org/wiki/Borg-Wa...6_transmission

And if you think lowering RPM doesn't help mileage, go drive 100 miles in 5th and then in 4th and compare your mileage.

Now I agree, there is a limit to how far you can lower (numerically) the gear ratio and still pull the speed you desire. My Vette tops out at 185 in 5th, not 6th, because 6th is too high of an overdrive to overcome the wind resistance at that speed. It can pull 70 all day long and get 28 mpg. Drop to 5th and it's more like 25.

As to the Harley, whether you'd get better mileage for lowering your RPM is indeed dependent on whether the lower rpm generates enough power to maintain the speed and results in lower brake specific fuel consumption. I'm betting a stock Evo or TC with 60-70 rwhp would benefit slightly in fuel economy from turning 500 less rpm on the highway at 70, but not enough to offset the cost of the transmission.

This is an interesting website that I think you could get the real answer if you cared to. It's geared (no pun intended) toward max speed but you could infer better mileage from the dyno sheets.

http://motorcycleinfo.calsci.com/Horsepower.html