why a 30 tooth sprocket?
#21
02-02-2010, 02:55 AM
Ultimate HDF Member
Aside from the 30 tooth pulley, you can also put a 70 tooth pulley on your wheel instead of the stock 66 tooth and raise the gear ratio that way too, which in my option is a lot easier than pulling open the tranny.
http://www.nightrider.com/biketech/calc_gearratios.htm
http://www.nightrider.com/biketech/calc_gearratios.htm
#23
02-02-2010, 07:37 AM
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#24
02-02-2010, 08:26 AM
Club Member
If you only change the primary it won't affect your speedo, which is driven from inside the gearbox. If you change the belt drive your speedo will be affected.
#25
02-02-2010, 08:29 AM
Club Member
I think you will find you are much better off than the guys here with later bikes. Harley make a SE kit to change your 25T compensator to 21T, which comes with a new chain. Baker make several alternative sizes. I have a 21T on my 03 Dyna as I mentioned earlier. Later bikes have a different primary set-up to your bike and mine. The benefits of changing are the same though!
#27
02-02-2010, 09:49 PM
Tourer
Update -
Rode to work today. I just like the feel - feels more like your in the power band. I had often heard the saying - A Street Bob is a Sportster on steriods. Well, now with the Stage 1 and the new gearing - thats more how it feels, and that's not a bad thing.
I also, made a reference to a start-up "bang" noise - I heard it was do to the stock compensator. Now with the new SE compensator - no more "bang" just a nice smooth turn over.
Rode to work today. I just like the feel - feels more like your in the power band. I had often heard the saying - A Street Bob is a Sportster on steriods. Well, now with the Stage 1 and the new gearing - thats more how it feels, and that's not a bad thing.
I also, made a reference to a start-up "bang" noise - I heard it was do to the stock compensator. Now with the new SE compensator - no more "bang" just a nice smooth turn over.
#28
02-18-2010, 09:55 PM
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so what can I do
All Harleys built for the last 20 years or so are fitted with stock gearing that reduces engine speed at the road speeds that noise emissions tests are done. It is common across all modern vehicles. The gearing we are all familiar with is there to keep the environmentalists and regulators happy, not for the riders' benefit!
We all fit 'stage 1' improvements, which undo the inlet and exhaust restrictions, but hardly anyone undoes the great harm to performance done by gearing. I replaced the 25T crank sprocket on my Dyna with a SE 21T kit. That has reduced theoretical top speed from 140mph to a sensible 117mph and increased rear wheel torque by 19%. That is the cheapest way to tune a Harley!
Later Harleys have a new design of primary drive and there are no alternative crank pulleys available at present. A 30T gearbox pulley reduces gearing to give the engine an easier time and increases rear wheel torque by 7%, which gives better performance across the entire rev range.
We all fit 'stage 1' improvements, which undo the inlet and exhaust restrictions, but hardly anyone undoes the great harm to performance done by gearing. I replaced the 25T crank sprocket on my Dyna with a SE 21T kit. That has reduced theoretical top speed from 140mph to a sensible 117mph and increased rear wheel torque by 19%. That is the cheapest way to tune a Harley!
Later Harleys have a new design of primary drive and there are no alternative crank pulleys available at present. A 30T gearbox pulley reduces gearing to give the engine an easier time and increases rear wheel torque by 7%, which gives better performance across the entire rev range.
#29
02-18-2010, 10:16 PM
Elite HDF Member
I will also be doing the SE compensator this spring... 'cause my ride also 'bangs' like a bitch when I start it. Has from day 1.
#30
02-18-2010, 10:17 PM
Elite HDF Member
Actually ... any time you change the final drive gear ratio, whether done with the sprocket in the primary case or the pulley from the trans or the rear wheel pulley, your speedo will be off ... reasoning otherwise is faulty ... the final drive ratio is affected either way ....
I think the ECM can be recalibrated to correct speedo to read the actual speed ... how much will depend on what your final drive ratio is--how much it changed from stock when you changed the sprocket/pulleys ... you will have to either look up or calculate it .... I believe the Andrews website has a table for the drive pulleys they sell showing 30T, 31T 32 (stock), 33T and 34T ....
Since I have a 5-speed 88CI, I have 6 speed 'envy' ... and have actually been mulling over the overdrive drive pulley, the 34T ... would reduce my highway cruising RPM by 6% .... I have never really thought that I lacked low end torque or felt it needed more 'grunt' ... so, guess I am 'swimming upstream' compared with most of the forum members replying on this thread ... (also, never saw any threads on converting to O/D drive pulley) ....
R/
'Chop
I think the ECM can be recalibrated to correct speedo to read the actual speed ... how much will depend on what your final drive ratio is--how much it changed from stock when you changed the sprocket/pulleys ... you will have to either look up or calculate it .... I believe the Andrews website has a table for the drive pulleys they sell showing 30T, 31T 32 (stock), 33T and 34T ....
Since I have a 5-speed 88CI, I have 6 speed 'envy' ... and have actually been mulling over the overdrive drive pulley, the 34T ... would reduce my highway cruising RPM by 6% .... I have never really thought that I lacked low end torque or felt it needed more 'grunt' ... so, guess I am 'swimming upstream' compared with most of the forum members replying on this thread ... (also, never saw any threads on converting to O/D drive pulley) ....
R/
'Chop