Discontinued product, for reference only.

*Does not fit 2022+ models

Want to unleash all the power your Honda Grom® can handle? Our 170cc Big Bore kit is the perfect addition for you ! The kit includes a ceramic coated cylinder, 61 mm forged piston, rings, pin, gasket kit and banjo bolts. Its compression ratio of 11.5 to 1 will allow you to still use premium pump gas and keep the reliability of a stock motor. Made from the best components available on the market, our 170cc big bore kit will amaze you !

WARNING

THIS IS AN AFTERMARKET PART BUILT FOR RACING PURPOSES ONLY. KOSO IS NOT RESPONSIBLE FOR ANY DAMAGES CAUSED TO THE PARTS, VEHICLE, OR TO YOURSELF AND OTHERS.  ENGINE PARTS ARE NOT UNDER WARRANTY NOR IS COLLATERAL DAMAGE OR COST OF LABOR, IN CASES OF MALFUNCTION.

https://www.youtube.com/watch?v=pcVJlqdgays

Specifications

  • Cylinder displacement: 169 cc
  • Cylinder material: Aluminum / Ceramic coated
  • Piston size: 61 mm
  • Piston type: Forged
  • Compression ratio: 11.5:1
  • Kit includes: piston, rings, pin, pin clips, gasket kit, banjo bolts and cylinder
  • fits Grom® and Monkey®

For more important tips and notes, see Honda GROM® FAQ page or download our Honda GROM® Caution PDF.

Instructions

  Download PDF
When using 170cc big bore kit only, customer must change or add the following parts:
Parts
Description
Mandatory
Suggested
Mini 3 - Air/Fuel ratio meter | Honda GROM
X
Mini 3 - Cylinder head temperature | Honda GROM
X
High flow injector | Honda GROM
X
Injector adaptor kit | Honda GROM
X
Hurricane racing air filter fits GROM only
X
Hurricane racing air filter fits MONKEY only
X
Connecting tube | fits GROM only
X
Intake tube | fits GROM only
X
34mm Throttle body | Honda GROM
X
High flow oil pump | Honda GROM
X
Camshaft | Honda GROM
X
ECU Modification
X
Addition of a fuel control box
X
Proper exhaust system must be used to prevent re-flow pressure and heat
X
Other
 

Instructions

  Download PDF
When using 170cc big bore kit only, customer must change or add the following parts:
* M = Mandatory | S= Suggested
Parts
Description
Mini 3 - Air/Fuel ratio meter | Honda GROM
S
Mini 3 - Cylinder head temperature | Honda GROM
S
High flow injector | Honda GROM
S
Injector adaptor kit | Honda GROM
S
Hurricane racing air filter fits GROM only
S
Hurricane racing air filter fits MONKEY only
S
Connecting tube | fits GROM only
S
Intake tube | fits GROM only
S
34mm Throttle body | Honda GROM
S
High flow oil pump | Honda GROM
S
Camshaft | Honda GROM
S
ECU Modification
M
Addition of a fuel control box
M
Proper exhaust system must be used to prevent re-flow pressure and heat
M
Other
S
 

Why Buy From Hurtle Gear?

  • 100% Genuine Parts
    We supply only authentic motorcycle parts and accessories from trusted, authorised brands.
  • Fast Dispatch from Western Australia
    In-stock items ship quickly from our WA warehouse for reliable Australian delivery.
  • Australian-Based Support
    Get help from real riders who understand the products we sell and the bikes they fit.
  • Trusted by Riders Australia-Wide
    We’ve received thousands of positive reviews across platforms including SiteJabber, eBay, Facebook and more.
  • Over 12 Years in Business
    Hurtle Gear has been supporting Australian motorcyclists for more than 12 years.
SKU MB623002
Brand Koso
Product Specifications