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Discussion Starter · #1 · (Edited)
Ive read so much about changing the sprockets on these little bikes that im not sure which one to trust, basically im looking to get the most top speed out of my 2018 grom and i want to know what the best setup would be that will still let the bike be a fun little ride, i would like the bike to easily stay in the 65mph range if possible, ive been told the top speed will come with break in of the motor and right now ive had the bike up to about 57mph...

and before i get any hate for asking this, yes i have searched, googled and all of that, just looking for real world experiences on these bikes from some of you guys
 

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Opinions vary widely.......my mostly-stock Grom was broken-in hard. While my perception is that the acceleration may have improved slightly after break-in, I never saw a significant increase in speed. My top speed on the flats with light wind was-and-is ~ 56 MPH.......I have about 4K miles on the bike.

The problem with using taller gearing to try and gain more top seed is that doing so comes at a consequence of loss in torque. Assuming an adult-sized rider, I am skeptical that you will achieve a reliable 65 MPH without getting into some engine mods. Changing the gearing, however, is one of the cheapest experiments you can try on the bike, so if you are curious, go for it.
 

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Discussion Starter · #3 ·
Opinions vary widely.......my mostly-stock Grom was broken-in hard. While my perception is that the acceleration may have improved slightly after break-in, I never saw a significant increase in speed. My top speed on the flats with light wind was-and-is ~ 56 MPH.......I have about 4K miles on the bike.

The problem with using taller gearing to try and gain more top seed is that doing so comes at a consequence of loss in torque. Assuming an adult-sized rider, I am skeptical that you will achieve a reliable 65 MPH without getting into some engine mods. Changing the gearing, however, is one of the cheapest experiments you can try on the bike, so if you are curious, go for it.

yeah it will be an adult sized rider, lol, im about 5'8 and 175 lbs, yeah i know it will cost me torque and ive definitely have seen it be a big "opinion" topic everywhere i look it up
 

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How much do you weigh? That's a huge factor I'd consider before considering gearing change.

With stock gearing, I think 65mph is attainable. Even going one down in the front to 14T I was able to hit 65mph all day, but I weigh 145lb geared up.

Sure, you could get more top speed by going up in the front, but it comes at a pretty big hit to acceleration.

There's not too much conflicting info online about gearing I don't think. Going down one tooth to 14T in the front is a common recommendation for some extra accel. Nobody really recommends going up to 16T in the front unless you have a BBK.

My $0.02, stick with stock gearing, let the bike break in, and go on a diet.
 
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I hit 70mph on my grom when it was stock and only change I made was go down one teeth in the front from 15-34 to 14-34. This was back in 2014-15 time frame and the minor changes was DIY the airbox and change the tires to Michelins 120/70 front and 140/70 rear and I weight 220-225 lbs back then. I think I also changed the F/I to a PC-150 and played around with the various heat range of the spare plug.

My first grom Jan 2014 I rode that thing like I stole it and it was fast for a stock grom. My second grom June 2014 I babied it and broke it in according to the Honda manual and that grom took forever to break the 60-65mph barrier even after a 1000 miles on the ODM.

I believe ride it like you stole it is a better way to break in the piston and seal the rings properly.

Dodge Rider says it best
 

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Discussion Starter · #6 ·
How much do you weigh? That's a huge factor I'd consider before considering gearing change.

With stock gearing, I think 65mph is attainable. Even going one down in the front to 14T I was able to hit 65mph all day, but I weigh 145lb geared up.

Sure, you could get more top speed by going up in the front, but it comes at a pretty big hit to acceleration.

There's not too much conflicting info online about gearing I don't think. Going down one tooth to 14T in the front is a common recommendation for some extra accel. Nobody really recommends going up to 16T in the front unless you have a BBK.

My $0.02, stick with stock gearing, let the bike break in, and go on a diet.

my weight is around 175, and a diet isnt happening, ive spent the last 3 months of non stop training and weight lifting, im not about to blow all my gains out and go back to a skinny little guy, lol, if anything ill gain more weight as i build more muscle
 

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Ive read so much about changing the sprockets on these little bikes that im not sure which one to trust, basically im looking to get the most top speed out of my 2018 grom and i want to know what the best setup would be that will still let the bike be a fun little ride, i would like the bike to easily stay in the 65mph range if possible, ive been told the top speed will come with break in of the motor and right now ive had the bike up to about 57mph...

and before i get any hate for asking this, yes i have searched, googled and all of that, just looking for real world experiences on these bikes from some of you guys
Without any mods??? for top speed your best bet is stock gearing w/tires inflated to max psi...

If you dont mind sprocket change with the least amount of top speed loss but a little more bottom end, change rear to 35tooth keep 15tooth up front, tire pressure to 30psi, to keep speedo accurate without speedhealer add 40series tire to rear set to 30psi

Changing the rear to 35 tooth instead of 14tooth up front will not rev out as fast in lower gears but still rev faster than stock and will have a better top end than 14tooth

Thru my experience anyway, https://www.hondagrom.net/forums/7-grom-talk/40136-gear-ratio-2-33-accurate-odometer.html
 

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, i would like the bike to easily stay in the 65mph range
Guys, answer his question. Ok, I will be the bearer of bad news.

A stocker is not going to easily stay at 65 mph. Not gonna happen. Hit it, possibly. Stay there, nope.

Not even with a exhaust & intake & probably not with a fuel controller.

Going to take CC's (TQ & HP) to achieve this goal & the stock or lightly modded motor is not up to the task.

FWIW, YMMV

Excuse me, I have to go put my flame suit on...:furious:
 
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been there and done it 65mph is EZ, just have to know what you are doing. Been there and done it all others are just following or being a Parrot.

Ride Safe.
Sure you hit 65. But you did not stay easily at 65, Up small hills, ect.

I bet my newly operated scrotum on it. :headbang:
 

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Sure you hit 65. But you did not stay easily at 65, Up small hills, ect.

I bet my newly operated scrotum on it. :headbang:

agreed. Even my 164bbk has a hard time holding 65 without being at or close to WOT. 160is lbs, dual sport tires, and a milk crate on the back
 

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62-64 max, real world, on a stockish bike flatland sitting upright is absolutely the norm. its documented all over the place. parrots be right regardless of whatever somebody wishes...

a good way to set your sprocket is to find out what rpm you hit a wall in 4th. then, either go UP on the rear, or Down in the front. this will get you past the rpm you need and you can actually use all the available the power in 4th., HOWEVER, the peril here is that the speedometer will then be off as its driven by the sensor on the output shaft of the transmission. id recommend a speedo healer, or at least a gps speedo app on your phone to make sure you aren't mind fucking yourself thinking adding a 14t sprocket suddenly yielded 78 mph on a stock bike with an intake and a pipe.

on a stock ecm bike, with stock gearing, accurate speedometer, the revlimiter will absolutely kick in at 73/74 mph real world (down a LONG hill, tucked.. ). this is just the way it is.

Hope this helps.
 

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been there and done it 65mph is EZ, just have to know what you are doing. Been there and done it all others are just following or being a Parrot.
Cisco,
Your exploits into the realm of modded Groms are rather legendary, so your opinion carries some real weight in my view.

This recent post of yours, however, is kind of troubling. I am not being a "Parrot," as you say -- a term by which I *think* you mean to refer to someone who just agrees with what others are saying -- I am simply posting my own direct observations. I tried a few modest things (bolt-on mods, etc) to get my bike to go faster, but I really never saw the increase in speed I desired from that ~ stock-ish engine. My experience may not represent that which everyone else is going to encounter, but it DOES represent my own experience and I AM telling the truth.

You say that you have been here and done that....and that it is easy? Please share this information with others, for the greater benefit of all.

What IS IT which one "has to know what they are doing" to make a stock Grom easily hit 65 MPH?

And while we re at it.....OP: jus so you know, changing your gearing will effect your speedometer read-out, as it is linked via the transmission.
 

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LOL u guys are so funny.

@WV_Grom - Don't answer if you don't want to, but was your testicle surgery cancer related? I just had a buddy, age 26, who had to undergo an orchiectomy. He's recovering well thankfully. But testicular cancer in my early twenties scares the hell outta me.
 

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62-64 max, real world, on a stockish bike flatland sitting upright is absolutely the norm. its documented all over the place. parrots be right regardless of whatever somebody wishes.......
Hope this helps.
Well.....it doesn't help me....sadly.......

M in SC,
You have always seemed to me like a knowledgeable guy with considerable experience and insight. Not trying to offend, nor do I wish to dissuade you from sharing your opinions. I am just trying make the argument that it seems like top-speed results on these bikes have been pretty inconsistent. Some finding a peak speed around 55 MPH......others hitting as much as 70. This is frustrating for those of us who tried to make their bikes go faster without much success.

As a contrasting data-point, consider Brock Davidson's "Stock-to-Brock" YouTube videos. He speed runs a stock Grom, briefly hitting 58 MPH (faster than mine)....he THEN mods the air-box, adds an exhaust, adds a Power Commander fuel controller, does a dyno-tuning session, and THEN hits a top speed of 64 MPH for about half-a-second of flicker on the speedo.......62 MPH was more of a sustained top speed......and Brock is a professional motorcycle tuner.

I cannot help but feel that there is sometimes a mythology of performance expectations which so easily gets propagated in these forums. I can only share my own observations.
 

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LOL u guys are so funny.

@WV_Grom - Don't answer if you don't want to, but was your testicle surgery cancer related? I just had a buddy, age 26, who had to undergo an orchiectomy. He's recovering well thankfully. But testicular cancer in my early twenties scares the hell outta me.
Opus,

No secrets here!

I was worried of the cancer thing too, being I am getting ready to knock on 60's door next year. Turns out it was a Hydrocele.

https://www.mayoclinic.org/diseases-conditions/hydrocele/symptoms-causes/syc-20363969

Thought I was going to have to borrow the neighbors Barbie wheel borrow to haul them around in. HaHa!

Rough after surgery. Will take 6 months to get back to "tea bagging" LOL
 
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