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97 ultra Andrews 27 cam Keith Black 9.5-1 pistons M&M injection.
Here is my question. Can I gain any pull in 1st gear if I reduce the drive gear by 1 tooth? What I would like is just a little more pull when taking off from a stop especially with 2 up. I am very satisfied with the power and torque while moving, no issues climbing hills that is all good. Any and all thought welcome.
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Yes, obviously any reduction in the drive, or increase in the driven diameter, will buy you more torque, you may be surprised.

I would switch one to two teeth on chain drives depending on top end speed or torque on my dirt bikes.

I have toyed with the same idea, let me know how she performs.
 

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I don't want to be the Guinea pig I am sure there is someone out there that was so curious that they have done this already. Perhaps one of the wrenches out there has some useful info on this topic.
 

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I have a stock 32 tooth drive gear on my bike. I am swapping that for an Andrews 30 tooth this winter. I have an rpm vs speed chart with both drive gears and in 6th gear at 70 mph the difference is 300 rpms. That means I am in the sweet spot of tge motors operating range at a decent cruising speed.
I have tested mileage at 60 mph in 5th and 60 mph in 6th and 5th believe it or not is easier on fuel. 6th doesn't over take 5th in fuel economy until 75 mph on my bike which is asking for a speeding ticket.
It's like putting gears in a cars rear end. I went from 3.27 gears in the rear of my mustang to 3.90s and the acceleration is unreal but it costs top end speed. Well on my Harley I may hit 100 mph for short bursts but I don't stay there long. A 30 tooth drive gear accomplishes the same thing and with a 6 speed your cruising mileage will increase because you stay where the motors most volumetric efficient.
Do it. You won't regret it
 

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I dropped my primary drive gear from a 25tooth to 24tooth and it does make a noticeable difference from a stop. More pull for sure. It is a relatively inexpensive mod, easier than changing the trans pulley and doesn't affect the speedometer.
 

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Hey Clevy, What are you running for your rear pulley on your final drive. I have two bikes, one has a 30/61 and the other is 32/65. It seems to me that that 30/61 runs at a higher RPM at 60-65 MPH. I would like to drop those RPM a bit in the cruising range. The 32/65 seems to be fine. Any suggestions
 

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1 tooth is a little more than 3%. It will be hardly noticable. It's a lot of work/money to swap the pulley on a Harley.

On the 6-speed bikes going 2 teeth smaller is popular. That's a little over 6%, but on a 5-speed it might raise your highway cruise RPM more than you would like. You would probably need a shorter belt too... might have no adjustment left.

I changed by 2 teeth (33 to 31) which is 7% on my bike. I love it that way, but I have an overdrive 6th gear (that went from .86:1 overdrive to .93:1). At 85 MPH it gained 217 RPM which is not really significant.
 

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Half crazy. I just posted in front of you. Hopefully you might be able to answer my question as well. Any thoughts
 

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Another option is to add 2 teeth to the rear pulley. About the same as one tooth on the tranny. I did it on my 07 six speed. Much cheaper and easier. Didn't have to change the belt.
 

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97 ultra Andrews 27 cam Keith Black 9.5-1 pistons M&M injection.
Here is my question. Can I gain any pull in 1st gear if I reduce the drive gear by 1 tooth? What I would like is just a little more pull when taking off from a stop especially with 2 up. I am very satisfied with the power and torque while moving, no issues climbing hills that is all good. Any and all thought welcome.
Thanks
Google - "primary gear change on harley". Lots of folks have changed their gear ratios using various methods - primary, tranny, clutch sprocket, final drive sprocket and six speed options.

However, I believe you will achieve what you want (more pull from a stop) with just the primary gear change by lowering one tooth. I did. Again, less cost and easier change than the other options.

Bakers website gear ratio and rpm calculator;
http://www.bakerdrivetrain.com/gearratios/rpmCalc.htm
 

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Half crazy. I just posted in front of you. Hopefully you might be able to answer my question as well. Any thoughts
You'll have to look into what pulleys will bolt up and if your belt will still work. To me, a little more RPM is good. Better passing power on tap.
 

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Another option is to add 2 teeth to the rear pulley. About the same as one tooth on the tranny. I did it on my 07 six speed. Much cheaper and easier. Didn't have to change the belt.
There you go what he just said.
HD did this on the 09 and new touring bikes
 

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Whichever way you decide to go, remember it will change your speedo reading. Many tuners will let you recalibrate for that.
 

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I changed the front belt pully on a 2007 1200 custom from a 29 tooth to a 28 tooth and it made 2 miles per hour diff. When the spedo showed 60 you was running 58 but you could tell a diff. on take off.
 

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a modification with the drive ratio has been done recently and is gaining in popularity because it works so well. it's by using the sportster rear sprocket on the wheel. the stock twin cam belt is supposed to be long enough to allow this all to work, and your factory belt will fit the sportster rear sprocket quite well. it will give better bottom end and put your motor into runnning at better rpm's at highway speeds. perhaps there's someone in this forum who's had experience with it.
 

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a modification with the drive ratio has been done recently and is gaining in popularity because it works so well. it's by using the sportster rear sprocket on the wheel. the stock twin cam belt is supposed to be long enough to allow this all to work, and your factory belt will fit the sportster rear sprocket quite well. it will give better bottom end and put your motor into runnning at better rpm's at highway speeds. perhaps there's someone in this forum who's had experience with it.
I put the sportster sprocket on my 07 Ultra and yes the stock belt works fine.
 
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