900 Scootworks pulley - RPM & MPH Question??

NewRoadie · 05-13-2008

Okay, lots of threads related to either Scootworks pulley's and/or speedometer error.

I am looking for before and after MPH vs RPM numbers. For example, before the front scootworks pulley my RPM at 75 mph was 4250. After the pulley install, the RPM at 75 mph was 3500. (NOTE: THESE NUMBERS ARE JUST MADE UP AND NOT ACTUAL)

I am actually looking for information from other 900 riders that have added the Scootworks pulley and have this information. Thanks!

Anyone . . . Bueller . . . Bueller . . .

hharada · 05-13-2008

Sorry, can't help you with actual tach and speedometer readings.

I've put ScootWorks front pulley on my 900 LT. I find the difference most noticeable in gears 1-4. I believe there is a difference at 75 mph on the speedometer, but the combination of high winds the two times I've put it on the interstate so far and undoubtedly higher actual speed at the same speedometer reading has made the difference harder to grasp.

You may have seen the specs on the Scootworks pulleys. The front is said to reduce engine rpm for a given road speed by 5.9%, the rear by 6.1%. Per Scootworks, a combination of both pulleys gives an 11.6% reduction (Don't know where the 0.4% loss goes, but that's what they say.)

Assuming the numbers are correct, if 3500 rpm gave you a particular speed before a pulley change, you could achieve the same speed at 3294 rpm with the front pulley change, 3286 rpm with the rear change, and 3094 rpm changing both.

I don't know if their numbers are simply calculated, or from field tests which would take into account friction differences, etc.

mavulcan900 · 05-13-2008

You can find some "without pulley" numbers at the bottom of this thread:
http://www.kawasakimotorcycle.org/fo...ustom-pic.html

I don't have the "with pulley" numbers, but you should be able to do the math using the numbers provided by hharada.

05-13-2008	#1 (permalink)
NewRoadie Old enough to know better BTK Intermediate Join Date: Jan 2008 Location: Surprise, AZ Posts: 162	900 Scootworks pulley - RPM & MPH Question?? Okay, lots of threads related to either Scootworks pulley's and/or speedometer error. I am looking for before and after MPH vs RPM numbers. For example, before the front scootworks pulley my RPM at 75 mph was 4250. After the pulley install, the RPM at 75 mph was 3500. (NOTE: THESE NUMBERS ARE JUST MADE UP AND NOT ACTUAL) I am actually looking for information from other 900 riders that have added the Scootworks pulley and have this information. Thanks! Anyone . . . Bueller . . . Bueller . . . __________________ Bryan (Big B) 07 Vulcan 900 Custom Candy Plasma Blue VROC Member #27075 MRCA Member Last edited by NewRoadie : 05-13-2008 at 01:33 AM.

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05-13-2008	#2 (permalink)
hharada Cruising In Fourth Gear BTK Intermediate Join Date: Dec 2007 Location: Colorado Posts: 218	Sorry, can't help you with actual tach and speedometer readings. I've put ScootWorks front pulley on my 900 LT. I find the difference most noticeable in gears 1-4. I believe there is a difference at 75 mph on the speedometer, but the combination of high winds the two times I've put it on the interstate so far and undoubtedly higher actual speed at the same speedometer reading has made the difference harder to grasp. You may have seen the specs on the Scootworks pulleys. The front is said to reduce engine rpm for a given road speed by 5.9%, the rear by 6.1%. Per Scootworks, a combination of both pulleys gives an 11.6% reduction (Don't know where the 0.4% loss goes, but that's what they say.) Assuming the numbers are correct, if 3500 rpm gave you a particular speed before a pulley change, you could achieve the same speed at 3294 rpm with the front pulley change, 3286 rpm with the rear change, and 3094 rpm changing both. I don't know if their numbers are simply calculated, or from field tests which would take into account friction differences, etc.

05-13-2008	#3 (permalink)
mavulcan900 Still On The Kickstand Join Date: Oct 2007 Location: MA Posts: 27	You can find some "without pulley" numbers at the bottom of this thread: http://www.kawasakimotorcycle.org/fo...ustom-pic.html I don't have the "with pulley" numbers, but you should be able to do the math using the numbers provided by hharada.

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