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Awesome! Thanks for the helpful reply!
I checked again and it's 7.2 ounces shipped
it's this one here:
Amazon.com: Vortex 3270-15 Silver 15-Tooth 520-Pitch Front Sprocket: Automotive
Vortex makes great sprockets. Note that for the Grom you will need a 420 Pitch sprocket.....

Currently, Vortex doesn't make a sprocket for the Grom.

PBI does: http://www.ruckhouse.com/index.php/pbi-steel-alloy-honda-grom-front-sprocket.html

https://www.steadygarage.com/store/pbi-honda-grom-125-front-sprocket-steel-alloy

You can also save significant weight by getting a Hybrid rear sprocket. Center portion is alloy for lightness, outer toothed ring is steel, for long-wearing quality.

http://japan.webike.net/products/21832711.html
 

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Vortex makes great sprockets. Note that for the Grom you will need a 420 Pitch sprocket.....

Currently, Vortex doesn't make a sprocket for the Grom.

PBI does: Custom Honda Ruckus Parts PBI Front Countershaft Sprocket for the Honda Grom

https://www.steadygarage.com/store/pbi-honda-grom-125-front-sprocket-steel-alloy

You can also save significant weight by getting a Hybrid rear sprocket. Center portion is alloy for lightness, outer toothed ring is steel, for long-wearing quality.

MADMAX : Rear Sprocket [MM19-0341S]
Here's Vortex's front sprocket that fits the Grom:
Dirt Bike Vortex Front Steel Sprocket | MotoSport

Same teeth, same pitch, lighter Sprocket. Are you sure? Just because it isnt marketed for the grom doesn't mean it doesn't fit.

I dont care as much about wear. I'm happy with an all-aluminum rear sprocket, and willing to change pitches for both sprockets if it means less parasitic loss.

Do you know the weight of the sprocket you linked?
 

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Here's Vortex's front sprocket that fits the Grom:
Dirt Bike Vortex Front Steel Sprocket | MotoSport

Same teeth, same pitch, lighter Sprocket. Are you sure? Just because it isnt marketed for the grom doesn't mean it doesn't fit.

I dont care as much about wear. I'm happy with an all-aluminum rear sprocket, and willing to change pitches for both sprockets if it means less parasitic loss.

Do you know the weight of the sprocket you linked?
I stand corrected on that. The Vortex website doesn't list one for the Grom.

I couldn't find the actual weight of that sprocket linked to.

You could switch to a 520 pitch setup. You'd need both sprockets and a new chain. The 520 setup would add weight, though, and negate the savings you'd get just using lighter sprockets in the 420 pitch. The low power of the Grom engine means the 420 setup is more than adequate. If installing a BBK with considerably more power a 520 changeover might be a good option to add.
 

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I stand corrected on that. The Vortex website doesn't list one for the Grom.

I couldn't find the actual weight of that sprocket linked to.

You could switch to a 520 pitch setup. You'd need both sprockets and a new chain. The 520 setup would add weight, though, and negate the savings you'd get just using lighter sprockets in the 420 pitch. The low power of the Grom engine means the 420 setup is more than adequate. If installing a BBK with considerably more power a 520 changeover might be a good option to add.
Thanks, you basically confirmed what I thought. I thought maybe there could be some crazy alloy developed for racing that would require the 520 chain, and would have been willing to do so.

My concern now is that the vortex sprocket might actually be the 7.2 ounces listed on Amazon, because it has the appearance of a thicker "collar" around the hole the shaft goes in. The sprocket you linked seems to have less metal removed via holes but also no appearance of the re-inforced collar. I'll contact companies this week. I may just end up buying both and asking a machine shop what they say. After all, it's not a 1000cc roadmissile
 

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so i recently went with a 30T in the rear and i can't pull 4th gear to save my life. I'm looking for more top speed over anything and like the max speeds i can hit in the lower gears but in 4th I'm no where near the top speed i was looking for as the RPMs never get high enough, would you guys recommend like a 32T in the rear or keep the 30 and add a tooth up front? thanks
 

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so i recently went with a 30T in the rear and i can't pull 4th gear to save my life. I'm looking for more top speed over anything and like the max speeds i can hit in the lower gears but in 4th I'm no where near the top speed i was looking for as the RPMs never get high enough, would you guys recommend like a 32T in the rear or keep the 30 and add a tooth up front? thanks
Adding 2 on the back or dropping 1 up front will net you about the same. You need more powaaa to help you pull through 4th gear.
 

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I'm running the 15t / 36t and really like the way it accelerates. 1st gear is shorter but that launch is FUN! I occasionally have people in full size pickups trying to race me. Before, 4th gear was useless unless I was going downhill or had the wind at my back. Now, 3rd gear is fantastic and 4th can really get after it. It can be a little slow to accelerate when riding into the wind, but nothing a little tuck or draft won't fix. I should probably get a speedometer healer soon since my mileage is racking up 5.12% faster.
 

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HardRacing sells a 'plug-n-play' unit that is a breeze to setup. They even have a video about it if you'd like a virtual 'try before buy'.
 

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Quick (maybe silly) question, does anyone know what gearing would get the speedo closest to actual speed without the need for a speedo healer?
 

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Quick (maybe silly) question, does anyone know what gearing would get the speedo closest to actual speed without the need for a speedo healer?
Up one up front will probably be dang close. Unless you're small though, a 125cc Grom usually doesn't have the power to run that gearing.
 

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Semi off topic depending how you look at it buuuut, I installed a 235 with the recommended 16t front and stock rear. I downloaded a speedo app on my phone to see the speed error, to my surprise actual speed was slower?!?! I was reading a speed of 68km/h (I'm in Japan with a jap 2016 SF) on my phone when my bike speedo indicated 74km/h. Could it be just a break in side effect or maybe stock gauge was off to begin with? Never verified stock engine and gearing with the app.
 

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Semi off topic depending how you look at it buuuut, I installed a 235 with the recommended 16t front and stock rear. I downloaded a speedo app on my phone to see the speed error, to my surprise actual speed was slower?!?! I was reading a speed of 68km/h (I'm in Japan with a jap 2016 SF) on my phone when my bike speedo indicated 74km/h. Could it be just a break in side effect or maybe stock gauge was off to begin with? Never verified stock engine and gearing with the app.
I read once that the European MSX 125's are off quite a bit on their speedo. Seems like they read higher than actual. Perhaps the Japanese models are the same way?
 

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I read once that the European MSX 125's are off quite a bit on their speedo. Seems like they read higher than actual. Perhaps the Japanese models are the same way?
Would be interesting if this were true. I had a slight inkling this may be true. And would answer a lot of questions on that 5speed tranny thread about hitting 145kmph on the kitaco neo.
Could be… If the speedo indicated 74, you went to 16/34 gearing, and assuming that the speedo is 10% higher than actual… That nets us an actual speed of 71. Of course, change that percentage that the speedo is off by, and that number changes too.

Id say recheck the speedo with stock gearing, and report back.
 

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May just try using alternete spedos like from another car driving next to me with stock size tires and whatnot, maybe my other phones and different apps. Will report back later
 

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Well, on a different note. After switching to the 140 rear tire my Piglet hasn't felt as peppy. Decided to try m_in_sc's recommendation and ordered a 35t rear sprocket today. I'm currently at 16/34.
 
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