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DHM 149cc All Inclusive Big Bore Kit for the 2022-2025 Honda Grom

$1,099.00
Crankcase Vent
ECU Flash Options
Oil Cooler

Here you'll find a comprehensive kit containing nearly everything you need to big bore your 2022-2024 Honda Grom (You'll need your own aftermarket intake and exhaust and we do have options linked below). By purchasing this comprehensive kit we make it as simple as possible to install by pre-gapping the piston rings before shipping. 

Includes:

  • DHM 149cc Forged Piston and Cylinder Kit
  • DHM S1 Camshaft
  • Kitaco x DHM 5-row Oil Cooler Kit OR Drow Sports x DHM 7-Row Cooler
  • High flow Honda fuel injector
  • AvailMS or MO Power Crankcase Vent Kit
  • NGK CR9E Spark Plug
  • DHM ECU Flash Service

Other Requirements:

  • Premium fuel (at least 91 octane, 93 is even better)
  • Quality synthetic oil of 10w40 weight or 20w50 for warmer climates

Base pricing requires you to mail your ECU in so we can program it. Once we receive it we'll flash it and send it back out with the kit so that it can all be installed together. You do have the option of purchasing a preflashed ECU as well for an additional $110.

If you already have your own aftermarket intake and exhaust setup, this kit is all you'll need. If you need an intake and exhaust, we do have a few options here:

Intake:

Exhaust:

Customer Reviews

Based on 9 reviews
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Anthony Mastro
Too early to tell.

I installed the kit myself which I was a little over my head, but with YouTube and talking to some mechanics around me, I pulled it off and she’s running the compression is astounding. The starter can barely turn it over. She ran a little rough at first, but it smoothed out I’m still being very gentle on it while I break it in my first big test will be January 4 when I go for a ride with about 50 or better grom hooligans i’m going to go easy on it till then then on that day, I will ride her like a rental car and see if she runs better than my ex-wife.

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Ryan Mccrea
Awesome.Woke the bike up.😀

Excellent Bang for the buck, very impressed. Every gear is useful now. gave me the low end, I was looking for. Thanks

M
Michael Sowinski
Amazing

This kit is exactly as shown. The quality of parts and fit of parts is exact. The ease of installation is super easy. Best purchase for the grom ever.

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Shawn Hendricks
Wow, I wish that I hadn't waited!

I started with stage 1 and then went to stage 2. I skipped stage 3 and went for the BBK kit. Easy install and the increase over stage 2 is very noticeable. I wish that I would have done it sooner.

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Moises Rodriguez
Super impressive!!!!

The quality of this big bore kit is unmatched! It is practically plug and play. The power increase is fantastic and if you run into any issues at any point, give DHM a call and they'll help you figure it out! Great communication and great quality parts! My monkey is a RIPPER now!!