Here you'll find a comprehensive kit containing nearly everything you need to big bore your 2022-2026 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:
Great kit for the Grom!! It sure wakes up the little beast. Pair it with a Yoshi exhaust and Chimera intake and tune. Lots more low/mid range grunt and better top end speed for sure. DHM is legit. David knows his stuff!! Solid dude.
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Anthony Beach
DHM 149cc All Inclusive Big Bore Kit for the 2022+ Honda Grom
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Robert
Awesome upgrade!
This is an awesome upgrade, you can definitely feel it has a lot more power all around and it makes the fifth gear actually usable on my 2024 Honda Grom!
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Doug Oldfield
149 bbk
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!
