Bore Diameter: 54mm
Stroke: 63.1mm (stock)
Compression ratio: 11.2: 1
 
*When S-stage Big Bore Kit is installed, FI-CON TYPE-e (Injection Controller) must be installed at the same time.
For competition use only.
*Related to the installation of a big bore kit
The crankshaft is subjected to increased torsion and deflection due to the significant increase in engine power and torque caused by the SP Takegawa big bore kit.
SP TAKEGAWA recommends to install crankshaft support adapter at the same time to reduce the load on the crankshaft.
The Crankshaft Support Adaptor adds ball bearing support to the end of the flywheel side of the crankshaft to reduce twisting and deflection and to increase the durability of the crankshaft.
Crankshaft Support Adapter for GROM (JC92) (Part No: 01-10-0149)

*When installing the S-stage Big Bore Kit, Sports Camshaft, or FI-CON TIPE-e, be sure to use the "High Capacity Injectors (G1) (Part No.: 00-00-00-0487) " must be installed at the same time.
*There may be changes in product specifications due to the manufacturer's reasons.
*Depending on the lot, the product may be delivered with the old price and label with the old JAN code before the price change.
■S Stage Big Bore Kit 145cc
By changing the cylinder and piston, the displacement can be changed from the stock 124cc to 145cc.

By installing the FI-CON TYPE-e (Injection Controller) at the same time, you can achieve a torquey output characteristic that is different from stock.
The cylinder is an aluminum steel sleeve cylinder.
Since the cylinder can be equipped with SP M5 temperature sensor, the cylinder temperature can be measured by separately purchasing a thermometer (compact LED thermometer with M5 temperature sensor).
S-stage big bore kits are available without or with sports camshafts.