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:
Bike goes better, but not quite what I was hoping for, still to run it in maybe it will get better, it is an improvement over stock. DHM have been very helpful. Fast service , answers emails promptly. Definitely recommend Dhm products.
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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!
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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!
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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.
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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!
