Love this kit. Has lots of low end torque, pulls the wheel off the ground with the crack of the throttle and stock gearing in first gear. I hope it’s as reliable as the stock bore.
Easy to install even for limited experience with mechanics. Perfectly setup by Dave. Great support and exactly what every Grom needs. Thanks Dave
Install can be done in a day. Adds more power and makes the grom much more enjoyable. I haven’t had any issues with the kit and I’m probably about 800 miles in. I’m seeing top speed cruising at 62-68 now. 4th gear is actually usable now. If you are on the fence just do it and you won’t regret it.
Very easy and straight forward installation. Be very careful not to over tighten the red oil line bolts as they snap easily. I emailed for a replacement almost a week ago and still haven't heard back.
Haven't broken in yet but clerences have been set and checked twice too abart twice lol but feels like it has a lil bit more low end power
**Kits are now shipping within 2 weeks from order date!
We are proud to introduce the first "all inclusive" big bore package for the Honda Grom!
The DHM 186 kit includes everything you need to convert your Honda Grom in to a big bore machine. You no longer have to piece parts together with expensive components to get more power out of your bike. Our kit utilizes hardware from TBParts along with an OEM Honda injector and our software tuning to create a reliable and powerful kit that makes the Grom easier and more fun to ride.
- 186cc Cylinder and Piston
- Complete Oil Cooler Kit
- OEM Honda PCX150 Fuel Injector
- DHM Reflash
- 16.5 HP and 14.5 Ft/lbs of torque! A gain of 74% in HP and 67% in torque over a stock bike. (Dyno chart available in photos above)
- 20-50mph in 5 seconds compared to a stock bike at 9 seconds
TB Camshaft. This kit is designed to be run with the TB camshaft. If you already have one, you do not need to select it. If you do not already own one, please add it by using the drop down menu when ordering.
TB Clutch Kit. If your stock clutch is worn, or you'd just like a harder bite, we offer the TB clutch kit as a $40 upgrade.
How the Reflash works:
You will need to send us your ECU to be reflashed for proper fueling to run with the kit. If you do not wish to send us your ECU, we can provide a core ECU for an additional fee. Please select your ECU option from the drop down menu when ordering. You can receive a refund of $75 when returning your ecu if you order a core when checking out.
Since our primary business is building race engines, we take a lot of pride and care in our engine assembly. Before shipping, we will check all ring gaps, and we will also align the rings in the piston and install the piston in to the cylinder for you with the alignment we recommend!
**An upgraded intake and exhaust are not required but are highly recommended!
Since we are flashing the OEM ecu, you can still use piggybacks on top of this kit should you decide to make any changes. If you would like to add a big valve head or change the cam, etc., you can do so and use your piggyback fuel controller (pcv, etc) to tune it as you normally would. The fact that we've reflashed the stock ecu for fuel and timing will actually provide a better base than the stock, unmodified ecu!
***Requirements and General Information:
The ECU reflash requires your stock narrowband O2 sensor to be installed and plugged in. If you have removed this to use another fuel controller, you will need to reinstall it. The ecu will learn and adapt over the first 15-20 miles, so acceleration and overall ride ability will increase up to that point.
Installation instructions are not included. If you are not capable of working on these engines, having a shop perform the install is recommended.
This kit is designed to be bolt-on, reliable power. However, at the end of the day the Grom engine is a very simple air-cooled engine, and heat is the enemy. If you plan on taking regular highway trips, an oil temperature gauge is highly recommended to make sure the engine does not overheat. OPMID and Koso both offer great options.