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

$1,149.00
by DH Motoring
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 14 reviews
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David S.
149cc Big Bore Kit

Ordered the 149cc kit and the complete package arrived remarkably fast. Install was very straightforward for not having performed such a task. There is a noticeable difference in power delivery compared to stock. Amazing products, amazing company and would highly recommend DHM!! Thanks very much!

J
James Kreihs
DHM bbk is a must have for a grom!!!

The kit is amazing! The help from David at DHM is even better. I’m sure he’s tired of my ph calls, but he didn’t show it. Even if there were a better kit out there, which i doubt there is, I don’t think the other companies would support their product to that extreme. I wouldn’t go to anyone else. FIRST CLASS! Thanks David!

L
Luis I
Bbk

Bbk went together smooth and gave the bike that extra power it needed to really wake it up. Highly recommend this kit to everyone looking for some more power out of there grom.

S
Sean M.
DHM 149cc complete kit

I absolutely loved slapping this kit on my bike, I can't wait to start it up when the new exhaust comes in, although I feel like it could benefit from an enlarged fuel line and some heavy duty headstuds just for peace of mind (Those are things I added). Otherwise this kit is the most quality and cost-effective kit for a boost of power. DHM you have truly our done yourselves. Thank you for putting together this kit and making it so affordable!

C
Cafes Customs LLC
5 Star Service!!

Great product and Great customer service make it easy to rate this 5-Stars.

The Kit came with everything needed to install and very straight forward. I did have a few questions during the install, called DH Motoring and they were very helpful in answering all my questions. Excellent communication as well as very knowledgeable about the product. The Quality of the parts are Top Tier.

What a difference in low end TQ and pulled smooth power to upper RPMs. Makes riding my 2024 Honda Grom a lot more enjoyable. I am currently running the bike on VP 101 octane fuel and the throttle response is amazing. The Tune on the ECM provided by DH Motoring is spot on. Crispy Throttle, super clean decel and very decent fuel milage.

I also installed a Lithium battery to increase cranking power at start up, made a noticeable difference.


10/10 Highly recommend!!

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