Better throttle response
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6th Gear
Joined: May 2011
Posts: 13
Likes: 0
From: Minnesota
Better throttle response
I hear a lot of people talking about doing motor work = bigger heads, new cam etc. but hardley ever hear people talking about changing gear ratios for a similar end result = quicker or higher top end..
Why is that?
Why is that?
Outstanding HDF Member
Joined: Apr 2008
Posts: 3,140
Likes: 17
From: Wisconsin
You hear of some, just not as much. I think there are some reasons ......... for instance, if I gear as such that I am quicker off the line, I lose top end and cruise at a higher RPM range resulting in greater fuel consumption and increased wear and tear. If I gear for top end, I lose that low end get up and go, however, each option is cheaper than motor builds. I did the latter on my shovelhead in the old days to get a very smooth highway cruise at lower RPM's. Now, spend the money, free up the flow, add the cams, add the displacement and now I get out of the hole faster, have increased my top end, have great cruising RPMS and have given up nothing in fuel efficiency, but I have emptied the wallet. Just my $.02.
Road Master
Joined: Apr 2008
Posts: 935
Likes: 1
From: Indiana
Hmmm, remembering my car engine days. The most cost effective way to gain low end torque is to change rear end gears from stock 2.43 or 2.71 to 3.73. Just have to add an adapter to correct the speedometer. You don't loose top-end power other than top speed, hence a 3.73 instead a 4.11.
How on a bike, other than the sprocket change, the final drive belt usually has to be changed as well, and that's not an easy job. Plus the speedometer calibration.
How on a bike, other than the sprocket change, the final drive belt usually has to be changed as well, and that's not an easy job. Plus the speedometer calibration.
Thunder max was a great option for my limited. I had a ton a fuel issues when I first had the bike, super low gas milage like I could watch the needle just go down while I was riding. Brought it in twice and finally got a t-max (and extra 800 just for the t-max) I did not want to spend. However, I matched up the t-max with fuel moto cermic headers, FM air and some Klockwerks four inch straight cut pipes, with 555 cams and push rod kit. Bingo, never had a worry again. THe bike sounds great and flys like the wind and the throttle is twist it and watch out.
Seasoned HDF Member
Joined: Dec 2007
Posts: 8,341
Likes: 714
you'll notice what 2 teeth can do if u go from an 07-08 to a 09 up,many with the to tall 07-08have had good results with gearing.some use a 2 teeth bigger rear pulley,others 1or 2 teeth smaller front pulley,theres also kits for front primary gear(b
(ut u can't run a comp with it)or a bigger ring gear on the clutch some have used combinations of all of the above,i think ?andrews has a gearing speed vs rpm calculator on its site.
(ut u can't run a comp with it)or a bigger ring gear on the clutch some have used combinations of all of the above,i think ?andrews has a gearing speed vs rpm calculator on its site.
Road Warrior
Joined: Jun 2009
Posts: 1,943
Likes: 3
From: NYC
do a google search for 30T/68T upgrades. A lot of folks do them. I have the parts in house to do mine soon. In my case...it will move the power band of my current config closer to the RPM range where I ride......but the 30T/68T in itself, is not a significant performance upgrade.
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I didn't just look at one or the other when I went through my motor last winter. I built a 107 with high compression pistons, ported heads and tw8 cams, (upgraded from a 103/se204 build with stock heads). At the same time I was building up the motor, I changed the overall drive ratio from 2.79 (32/66 final drive) to 3.07 (30/68). I'm of the opinion that you want your powerband and gear ratio to match for best overall performance, both acceleration and cruise.
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