I have a couple of issues with the kit so far, similar to the recent reviews.
1. The oil cooler bracket provided isn't the one shown. I also had to grind the bracket just to fit on the bolts.
2. Cylinder head threads aren't tapped deep enough. Couldn't get the banjo bolts that came with the kit to seal. Ended up having to buy news ones, and even now theyr'e leaking.
3. The top cylinder head hole was threaded at angle, which probably contributes to the leak mentioned in #2.
4. I seem to have a sticking idle. bike starts up fine and idles at 1700, but after its warmed up and I'm out riding, whether I come to a stop or pull the clutch in, Revs stick anywhere between 2200 - 3000 RPM. Not sure if this is tune related or not.
Not really happy so far to be honest.
THE KIT IS WELL BUILT BY TB MAKES A LOT OF POWER WORTH THE MONEY BUT NEEDS SOME R&D
#1. OIL COOLER BRACKET IS NOT WHATS IN THE PICS ONLY PLACE TO INSTALL IT IS ON HEAD STUDS HAD TO GRIND CORNERS NOT HAPPY WITH THAT I WILL BE MAKING A NEW ONE SOON.
#2. OIL COOLER BANJO BOLTS ARE JUNK WOULD NOT SEAL ON CYLINDER BROKE ONE WITH NO FORCE AT ALL. HOLES ON CYLINDER ARE NOT TAPED DEEP ENOUGH BOLTS BOTTOM OUT.
#3. WE COULD NOT FIND A REPLACEMENT BECAUSE THE THREAD IS 27 BY 10MM THERE IS NO TAP FOR THAT SO WE HAD TO MAKE SOME ON OUR LATHE FROM 6061 ALUMINUM THIS SHOULD HAVE BEEN DONE FROM THE GET GO.
TO SUM IT UP ITS A NICE KIT DHM & TB NEED TO SOME R&D. INSTUCIONS WOULD BE NICE WITH PICS AND OR A INSTALL VIDEO ON YOUTUBE SHOWING EVERYTHING STEP BY STEP. I'LL LEAVE YOU WITH THAT YOU HAVE MY EMAIL
The kit seemed to go together well but the oil cooler bolts won’t thread into cylinder. DHM told me they don’t know what’s wrong with it and I would have to tap them so there threaded for the bolts. So much for a bolt on kit.
Easy upgrade, nice modest power gain, what I hoped for. I already had the TB Cam installed, plus the typical exhaust and air intake mods. Before the upgrade the bike was tapped out pulling my 230 lb of lard to 55-60mph, now it has no problem, not a strain, comfortable with power to spare... Well worth it!!!
This bbk is a must have super simple gives that extra kick the grom needs looking forward to buying the new head and increasing power thank you dhm deff worth the money all my grom buddies wanna do the kit now
**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.