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Discussion Starter #1 (Edited)
And an estimated 150 lb. rider including gear. Didn't we all wish to be 6'4'' and full of muscle? Unfortunately, my physiche topped out in 10th grade.

On my Grom I reached 0-60 mph almost in 13 sec. The top stop light to stop light speed was 59 mph before the red light that cut the fun in 13 sec. My speedo is off due to a 36T (+2 teeth) on the rear sprocket. I've calculated a 3-5% under value indicated which is about 2 mph. That means my indicated 59 mph is more like 57 mph and my (you'll see) indicated 74mph is more like 72 mph.

The lead in:

https://www.youtube.com/watch?v=NHZVb4Gqhfs&feature=youtu.be


The top speed run:


The almost zero to sixty :)

 

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:happy1:
 

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And an estimated 150 lb. rider including gear. Didn't we all wish to be 6'4'' and full of muscle? Unfortunately, my physiche topped out in 10th grade.

On my Grom I reached 0-60 mph almost in 13 sec. The top stop light to stop light speed was 59 mph before the red light that cut the fun in 13 sec. My speedo is off due to a 36T (+2 teeth) on the rear sprocket. I've calculated a 3-5% under value indicated which is about 2 mph. That means my indicated 59 mph is more like 57 mph and my (you'll see) indicated 74mph is more like 72 mph.

The lead in:

https://www.youtube.com/watch?v=NHZVb4Gqhfs&feature=youtu.be


The top speed run:


The almost zero to sixty :)

That's pretty neat, Leo! :)
I haven't run my engine over 8,000 yet. (lol)

I'll be out riding around tomorrow (Saturday)… up Fernwood, across Saddle Peak, down Stunt to Mulholland, and west to the King Gilette Ranch where my wife has a painting exhibition. For me it's just another excuse to take a ride. ;) If you're riding, maybe I'll see you.
 

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And an estimated 150 lb. rider including gear. Didn't we all wish to be 6'4'' and full of muscle? Unfortunately, my physiche topped out in 10th grade.

On my Grom I reached 0-60 mph almost in 13 sec. The top stop light to stop light speed was 59 mph before the red light that cut the fun in 13 sec. My speedo is off due to a 36T (+2 teeth) on the rear sprocket. I've calculated a 3-5% under value indicated which is about 2 mph. That means my indicated 59 mph is more like 57 mph and my (you'll see) indicated 74mph is more like 72 mph.

The lead in:

https://www.youtube.com/watch?v=NHZVb4Gqhfs&feature=youtu.be


The top speed run:


The almost zero to sixty <img src="http://www.hondagrom.net/forums/images/smilies/smile.png" border="0" alt="" title="Smile" class="inlineimg" />

very cool, this is the kind of stuff I like to see. It’s hard to explain the reason I’m building a fast mini bike. Why not get a 250 supermoto, a ktm duke, or an Africa twin? It’s just fun to ride. What other bike can race LEGALLY light to light??? I rode my wife’s bike the other day, a 600 v-twin, BORING!!

Use your phone to get a gps speed. I love the light to light!! Btw, I have lost 14 pounds. It does matter.
 

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you be surprise how many cars or even other motorcycle that I beat light to light with my grom, of coarse it isn't stock but a 181-4v with all the support hardware. I came next to a 3 group rider on 600-1000c bikes near Levi's stadium and when the light turned green I went for it and the 1000 and one of the 600 passed me before the next light and the third guy pulled up to me and asked if the grom was bored out and I said no it just had loud pipes which I lied and all 3 sport bike riders talked to each other and when the light turned green I went for it again with no response from the 3 group riders.

Same thing with most cagers in Santa Clara valley and the only car that I can't beat light to light is the Tesla electric cars or a fully modified hot rod.

Like I say ride it like you stole it or until it blows up.
 

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At 6'3 and 220lbs I'm not winning any races. I haven't ridden my grom since adding the reflashed ECU, exhaust & long tube intake but Im sure its going to add more noise than speed. I like slow bikes anyway, my other two bikes are a WR250R and an Africa Twin.
 

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My speedo is off due to a 36T (+2 teeth) on the rear sprocket. I've calculated a 3-5% under value indicated which is about 2 mph. That means my indicated 59 mph is more like 57 mph and my (you'll see) indicated 74mph is more like 72 mph.......
Assuming a stock front sprocket and stock wheel diameters, I would *think* that your actual speed vs. the speedometer-displayed speed would be the result of multiplying your speedo-indicated speed by the ratio of the stock/modified rear sprocket teeth:

Stock rear sprocket is 34 teeth; you went up two teeth using a 36-tooth sprocket: 34/36 = .944.....so

59 MPH (displayed) x .944 = 55.7 MPH (actual).

74 MPH (displayed) x .944 = 69.9 MPH (actual).

At least that is what I think......feel free to correct me if I am wrong......
 

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Discussion Starter #9
Assuming a stock front sprocket and stock wheel diameters, I would *think* that your actual speed vs. the speedometer-displayed speed would be the result of multiplying your speedo-indicated speed by the ratio of the stock/modified rear sprocket teeth:

Stock rear sprocket is 34 teeth; you went up two teeth using a 36-tooth sprocket: 34/36 = .944.....so

59 MPH (displayed) x .944 = 55.7 MPH (actual).

74 MPH (displayed) x .944 = 69.9 MPH (actual).

At least that is what I think......feel free to correct me if I am wrong......

That is one way to do it for sure! No, you're not wrong your math and reason is legit. However, I've made my estimates based on my Grom's odometer inaccuracy. My commute to and from work is 34 miles to work and 34.5 miles to home. I've made the measurement several times with several vehicles. It's not exact every time with all vehicles but it is close enough for estimating which is all I'm doing. My +2T or 36T Grom shows 35.6 miles to home. Therefore, I'm using for the adjustment:

34 miles / 35.6 miles = .96
.96 * 74 = 71.0

My top speed to date (prior to the Chimera styled radiator hose mod and with side panels removed) has been 76 mph at which point the rev limiter (upped +500 rpm) kicked in. So for hauling ass on the So Cal Fwys I try not to exceed 75 mph on the speedo (or 75 mph * .96 = 72 mph est). If I hit the 76 mph mark, (76 mph *.96 is 73 mph) I bounce off the limiter just like a stocker will do at 73 mph if it can get there.

No doubt though I can tell you all that the radiator hose mod with the pod filter has made a measurable increase in how frequently and how long I can reach and maintain top speeds over 70 mph. It is so obvious. In the top speed video posted I was on my standard speed route where previously I could only reach an indicated 65 mph on 3 or 4 occasions. If you want to go faster for longer with the stock engine open that intake all the way and ditch that air box!!

I believe there are three factors involved in my last mod.

1) The increase in air volume into the throttle body at all rpm's and speeds (disregarding intake air velocity which is not a noticeable thing for a stock Grom engine I think).
2) The removal of the air box. I believe the air box acts as an air dam that produces a lot of drag. Along with the side scoops the effect is like a mini parachute that is getting pushed into the wind. Removing the air box will help you go faster with your side panels on.
3) The crank case blow by gasses are now routed to the atmosphere and only clean, filtered air is getting sucked into the throttle body for mix and combustion.

For the comment ready that shows up like clock work, to the effect of "... it's just one more thing then I'll really notice a difference..."

I've done it! I have no desire to get a 143 cc bbk anymore.
 

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Discussion Starter #11
There is speedometer error above and beyond the odometer error. Just so you know.

You need to GPS your speed.
This forum has helped me get the most I can out of my Grom without going to a bbk and for that I'm thankful for all your inputs. You all helped me make it happen, for sure. My speed indicator is measure by how long does it take me to get to work When I rode a Hyabusa it was about an hour and when I ride my Grom it's about an hour :)
 

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i'm just saying that you keep quoting speeds, but aren't taking errors into account. the error you are proposing is only gearing error, not factory speedo error (which can be significant). so while from factory the odometer is correct, the speedo is not. this is intentional as a speedo reading a little bit optimistic is much less a liability than one reading incorrectly the other way.
 

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Discussion Starter #13
i'm just saying that you keep quoting speeds, but aren't taking errors into account. the error you are proposing is only gearing error, not factory speedo error (which can be significant). so while from factory the odometer is correct, the speedo is not. this is intentional as a speedo reading a little bit optimistic is much less a liability than one reading incorrectly the other way.
Error on the error will always be. I'm quoting the speeds on my speedometer with the 1 and only 1 change being a +2T on the rear sprocket. Read into it whatever you want.
 

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Discussion Starter #14 (Edited)
Error on the error will always be. I'm quoting the speeds on my speedometer with the 1 and only 1 change being a +2T on the rear sprocket. Read into it whatever you want.
And the +500 rpm increase to the limiter

And the removal of the oil spinner

And the removal of the CA smog box and ecu setting

And the heavy duty drive chain

And the speed screen! lol... Sorry bros, you may be too heavy for a Grom.
 

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Discussion Starter #15 (Edited)
And the +500 rpm increase to the limiter

And the removal of the oil spinner

And the removal of the CA smog box and ecu setting

And the heavy duty drive chain

And the speed screen! lol... Sorry bros, you may be too heavy for a Grom.
And the air box removal replaced with a pod filter over a radiator hose clamped to the throttle body

With a hole drilled into it for the air intake temp sensor

And the crank case breather hose routed to an open air filter.

I'm probably not leaving out one more thing. I got them all... On the Grom If you can't do it go bbk.
 

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Discussion Starter #17
We're talking 2 mph at most? That's actually insignificant.

In my last speed test I hit 74 mph and previously I hit 76 mph... why is that so hard for you to believe?

 

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on most bikes the factory speedo error is >5%. it gets worse as your tire wears


anyway, you can keep posting your speedometer. but nobody else trusts it, you'll see this in one of the millions of threads just like yours.
 

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Discussion Starter #19
on most bikes the factory speedo error is >5%. it gets worse as your tire wears


anyway, you can keep posting your speedometer. but nobody else trusts it, you'll see this in one of the millions of threads just like yours.
An honest commentary and experience can not be trusted? I trust them when I see them. I'll pontificate for you; :) I love your bait... I've gone 108 mph on my Drz400s. My '96 ZX-6E cruised at 135 mph chompin at the bit. My '95 ZX-6R did 140 mph when I backed off for the nut job in the porsche. My '85 FZ750 did 135 mph and started to wobble. My XN-85 turbo cruised all night at over 120 mph. My '86 XR 250 did over 70 mph. My 1200R Roadster will cruise at 114 mph before the engine cut at 115 mph. My '97 CBR600F3 has no speed limit and the same for my '98 ZX-6E. My '06 636 is in no doubt faster than them all. And my Grom rips all day at over 70 mph, bitch!
 
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