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Top speed on a street motorcycle determined by gear ratios as opposed to horsepower and Harley typically gears it's motorcycles for a top speed of about 110 mph. I believe this is what the Street 500 and 750 are both geared for just like my 1200 Sportster. You can, of course, change the rear sprocket for a higher top speed but I wouldn't recommend doing it or riding that fast.
 

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When I was riding the 500 delivered to Grand Junction's dealership on the highway at WOT with no grade it never went above 82 MPH. (laying on tank) Downhill it did hit 89 MPH. (Laying on tank toes tucked and knees slammed to the engine and air cleaner.

While top speed on a dyno maybe 110, at a point you are fighting as much resistive drag and turbulence as the HP can overcome.


No dispute but I wonder if it was gearing. I haven't checked to see if the 500 and 750 have different final drive gear ratios. H-D could very well of geared the 500 lower to improve the performance at lower speeds to compensate for the lower hp of the engine.


I did notice that the 500 and 750 both had excellent low speed (i.e. below 50 mph) performance and different gearing could account for that. It's less expensive to change the drive sprockets than it is to change the gears in the tranny to achieve similar results.
 

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take it to the autobahn with a buddy that has a truck and draft behind him, best way to really push it to the limit, little wind resistance :D

kidding.
The maximum possible speed obtainable is achieved by riding off of a very high cliff to determine terminal (and I mean terminal literally) velocity. This should only be attempted by trained professionals on a closed course. LOL
 

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500 & 750 final drive gearing same. 80T / 30T.

Interesting. Being a bit lazy this morning have you compared the transmission grearing?


In theory one would typically limit the final gear ratio to roughly the top of the powerband and the gearing of a lower hp motorcycle would be lower than for a higher hp motorcycle (or geared based upon a maximum speed desired) and I assume that both the 500 and 750 have the same redline for rpm.


One of two factors will always limit maximum speed. Either the rpm in high gear (geared so low the engine won't rev any higher) or the hp of the engine (not enough power to go any faster).


In any case there's really no need to go more than about 70 mph and, at least for me, my preferred speed is really more in the 50 mph or less range for enjoyable riding. My favorite roads are often limited to 20-25 mph on the turns and perhaps 40 mph on the straights. I really do love the back country roads along winding creeks and rivers and I never like being rushed to get anywhere. A motorcycle to me isn't as much transportation to get from one place to another as it is a journey. I all too often don't even make it to where I was headed to begin with.
 

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