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Discussion Starter · #1 ·
My '06 VRSCR has the following mods; topless ( stock filter), self mod pipes, V&H fuel pac, 26 T sprocket, lowered front & rear ( Works shocks). In three trips to the drags, I can get a best of 12.35 clustering around 12.5 at 106 to 107 mph. Using a MPH to weight calculator, I've got about 85-86 hp at the rear wheel. This would be about right when I compare to others Vrods speed/ et/ dyno charts. Question is, where the #*^! is the other HP ? I would think that tolerance would be in the 5% range, this is 20% ! Nothing seems to be out of whack mechanically, only 3500 miles on the bike. Oil change at 500 & 1000, second change to synthetic. Is this common to the R ? What makes the difference ? Suggestions ? :stilpoke:
 

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RIP ALEX
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What are your 60 foot times? May not be leaving the hole hard enough. I could only pull 12's and my 60 foot times were horrible
 

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The Hawk
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How much do you weigh? Total weight has a big influence on 1/4 mile times. When mine was similar to yours, high 11's were pretty easy with an occasional 11.6 when it hooked good.

Mike
 

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Discussion Starter · #4 ·
I weigh 195 pounds, took that into consideration on the mph / hp calculations. The 60' times are between 1.95 to 2.05 consistently. Other bikes set up for drag race were showing 1.7 to 1.9. ????
 

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orig member feb 2004
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swampboogiedoug said:
I weigh 195 pounds, took that into consideration on the mph / hp calculations. The 60' times are between 1.95 to 2.05 consistently. Other bikes set up for drag race were showing 1.7 to 1.9. ????
1.6'S TO 1.70'S Are common 60' times with a 28 tooth pulley.
you are not leaving very hard with 1.90's,what rpm are you launching at?
What rpm are you shifting at?
 

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Discussion Starter · #6 ·
I leave between 5500-6000, rear tire spins for 3-6 feet. Lower rpm bogs, more gives more tire spin. Lower pressure marginal effectiveness. Shifts at 7500. Shifting at rev limiter drops et to 12.8 I'm thinking its an HP problem rather than operator error.
 

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The obvious answer to a rear wheel horsepower/torque question is to put the bike on a dynamometer, determine your baseline values then continue testing (on the same dyno) and recording as you make changes to the bike. The downside is that it's costly if you plan to make a lot of changes.

It's possible to gather about the same information using either one of the performance meters (G-Tech, Veypor, Tazzo, AutoMeter,etc.) or spark analyzer software like Road Dyno at a much lower cost.

For motorcycle use, the G-Tech type meters can be hard to use because they use accelerometers which are affected by any wobbling at launch. Veypor may have fixed that problem, they are offering a motorcycle version of their device. (I have a bunch of website links if you want them.)

The spark analyzer approach seem well suited to motorcycles since you're recording spark pulses during a run without depending on the vehicle being stable -- and you can put together a system for under $100. At least that was true a few years ago when I was dinking with this stuff. I still have the Road Dyno software. (If you want to know how it works, Google "Road Dyno", there is plenty of info available out there and I've probably forgotten more than I ever knew.:) )
 
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