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Discussion Starter · #1 ·
I got out on I75 last night for fun, and managed 78mph. I'm running a 16T front sprocket, so it was 68 or 69 indicated on the bike's speedo. I'm confident that with the Yoshi exhaust I'll be able to break 80.
Conditions were light traffic moving fast (I was able to get into a pack of cars/trucks and kind of hang in the slipstream they created), clear skies, 75 degrees. I have a 16T and I'm running a K&N cone filter inside my airbox. I was running it directly on the throttle body but it sounded like shit with the stock exhaust.
Has anyone hit 80 yet?

Speedometer Auto part Gauge Measuring instrument Tachometer
 

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wow.. the fastest i have been on my grom was 68-69 on the speedo the other day going down hill on hwy 74 just to get to the next exit.. i hit the rev limiter.. it actually scared me the first time.. lil different than the ruckus rev limiter..
 

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This makes me want to install my 16 tooth right now and not wait for my pipe and air box mod. You might have the fastest Grom in the US.
 

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and which K&N are you running?
 

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i thought the bike has a factory speed limiter? your gps can be way off, were you drafting a car or going down a hill? how in gods name can you get more mph outta the same hp when the stock sprocket doesn't hit its max mph. this is confusing.
 

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HP DEPICTS top speed, if you could hit 78 with 1 up in the front why isn't everyone hitting 74 mph which the top speed for stock gear ratio, drafting a car an having wind behind you isn't a real number because that can't always be achieved.


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Discussion Starter · #8 ·
This makes me want to install my 16 tooth right now and not wait for my pipe and air box mod. You might have the fastest Grom in the US.
The 16T is good for cruising, but I usually run the stock 15T around town. You do give up a little acceleration with the 16. Honestly they're so easy to swap out I keep them both with me. And I doubt I have the fastest Grom lol! I'm still running stock exhaust with a cat.

and which K&N are you running?
The regular one that everyone else got, R-1100 I think. I'm just running it inside the airbox to quiet it down a bit. I'm trying to find a suitable aluminum tube to relocate the filter and ditch the airbox all together. It's just too loud and shitty-sounding when you run the filter directly on the throttle body with stock exhaust.

i thought the bike has a factory speed limiter? your gps can be way off, were you drafting a car or going down a hill? how in gods name can you get more mph outta the same hp when the stock sprocket doesn't hit its max mph. this is confusing.
Not a speed limiter, a rev limiter.
He's running 1tooth bigger front sprocket, so higher top speed than stock is posible.
If he was drafting then it is quite posible.
Even so 78mph is impressive
This^

I was in a pack of cars. On the highway drafting is different. There are so many vehicles moving together that there is this huge column of air moving the same way. I was behind a big SUV with more cars beside me and behind me, cooking along at 70+ for a few miles. I wanted to see if I could hit the limiter in 4th so I had to tuck in all the way and thats when I hit 78. I wasn't even looking at my GPS or speedo. I only know that I got to that speed because my GPS app saves the top speed from each trip.

As soon as I changed lanes to exit and got out of the pack of cars the tidal wave of air resistance calmed my high speed party down pretty quick.
 

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HP DEPICTS top speed, if you could hit 78 with 1 up in the front why isn't everyone hitting 74 mph which the top speed for stock gear ratio, drafting a car an having wind behind you isn't a real number because that can't always be achieved.


Sent from my iPhone using HondaGrom.net
Top speed isn't that simple. First of all the engine does not make peak power at redline/rev limiter. HP drops off not leaving you enough power to overcome the rising drag against you as speed increases. The trick to getting the absolute max speed out of a set amount of horsepower would be to push the HP curve out as far as possible (with gearing) while keeping it above the curve of limiting drags against you just below it as long as possible.

Acceleration will slow but as long as the HP is more that what is needed to overcome drag it will accelerate until drag overcomes HP which can possibly be a higher speed that what is obtainable with shorter gearing.

The OP also stated he was using some drafting which lowered the HP needed to go that speed.
 

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Hp is a number depicted by bore stroke an 5252 an tq, hp does infact depict the max mph a vehicle will do with it's set drag an weight, max power of this bike is at 8k an I can't see people being able to hit that with longer gear ratio especially considering they can't do it with this stock gear ratio.


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The 16T is good for cruising, but I usually run the stock 15T around town. You do give up a little acceleration with the 16. Honestly they're so easy to swap out I keep them both with me. And I doubt I have the fastest Grom lol! I'm still running stock exhaust with a cat.



The regular one that everyone else got, R-1100 I think. I'm just running it inside the airbox to quiet it down a bit. I'm trying to find a suitable aluminum tube to relocate the filter and ditch the airbox all together. It's just too loud and shitty-sounding when you run the filter directly on the throttle body with stock exhaust.





This^

I was in a pack of cars. On the highway drafting is different. There are so many vehicles moving together that there is this huge column of air moving the same way. I was behind a big SUV with more cars beside me and behind me, cooking along at 70+ for a few miles. I wanted to see if I could hit the limiter in 4th so I had to tuck in all the way and thats when I hit 78. I wasn't even looking at my GPS or speedo. I only know that I got to that speed because my GPS app saves the top speed from each trip.

As soon as I changed lanes to exit and got out of the pack of cars the tidal wave of air resistance calmed my high speed party down pretty quick.
my point here, the 16t will actually make you lose power unless thrown outta a plane or going down thrill hill, i love the research an development here, but with a stock sprocket an intake mod i can draft an do 72mph but as soon as im outta the draft i drop down to 67 or lower depending on surface/air.
 

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I got out on I75 last night for fun, and managed 78mph. I'm running a 16T front sprocket, so it was 68 or 69 indicated on the bike's speedo. I'm confident that with the Yoshi exhaust I'll be able to break 80.
Conditions were light traffic moving fast (I was able to get into a pack of cars/trucks and kind of hang in the slipstream they created), clear skies, 75 degrees. I have a 16T and I'm running a K&N cone filter inside my airbox. I was running it directly on the throttle body but it sounded like shit with the stock exhaust.
Has anyone hit 80 yet?

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also your gps app can be 2-5mph off depending on how far you are from a tower or phone proccessing speed.
 

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Discussion Starter · #13 ·
Hp is a number depicted by bore stroke an 5252 an tq, hp does infact depict the max mph a vehicle will do with it's set drag an weight, max power of this bike is at 8k an I can't see people being able to hit that with longer gear ratio especially considering they can't do it with this stock gear ratio.


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I can bang off the rev limiter in 4th with no problem with the stock 15T
 

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Discussion Starter · #15 ·
also your gps app can be 2-5mph off depending on how far you are from a tower or phone proccessing speed.
I'm running the Ulysses Speedometer app for Android on a Samsung Galaxy Note 2 on 4G in the middle of downtown Atlanta. If there is anything more accurate than that, I'm not aware of it.
 

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ive also banged the revlimiter down a hill drafting somone, kinda scared me but its not sustaniable open highway flat surface noone around. not even tucked.
 

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I'm running the Ulysses Speedometer app for Android on a Samsung Galaxy Note 2 on 4G in the middle of downtown Atlanta. If there is anything more accurate than that, I'm not aware of it.
they are still inaccurate maybe only 2 mph though because your in a big city, but phone gps are off even when im riding in a car you can see it.
 

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Nice going,
what is your weight so we can compare rider's weight and top speed on the Grom. Also are you using stock tires or something else, thanks for any info and ride safe.
 

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Discussion Starter · #20 ·
Nice going,
what is your weight so we can compare rider's weight and top speed on the Grom. Also are you using stock tires or something else, thanks for any info and ride safe.
I'm 5'9.5" and 125lbs. Stock tires, and now that you mention it I noticed this morning that both of my tires were at 25psi, so if they were properly inflated to 29 I might have squeezed out one more mph.
 
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