50 CC chinese engine tuning

Barnone · 05-15-2024, 12:29 PM

"A 139fmb big bore kit is available for the 139FMB OHC Cub Engine. A big bore kit can be used to increase the performance of an ATV or dirt bike by replacing the stock cylinder bore and piston with a larger version. This provides more displacement, increased combustion flow, and more torque."

Google "139fmb big bore kit" or "k157fmi big bore kit"

or

"A big bore kit for a 139fmb engine requires a cylinder, piston, crankshaft, head, and gaskets. Some recommend replacing the engine instead of trying to modify the existing one. A 125 cc pit bike engine can be purchased for around $300, and there are also many inexpensive and reliable drop-in replacement engines available."

I don't know if it would work but I would prefer the engine swap if it can be fitted.

05-15-2024, 12:29 PM	#23
Barnone Join Date: Feb 2007 Posts: 1,354	"A 139fmb big bore kit is available for the 139FMB OHC Cub Engine. A big bore kit can be used to increase the performance of an ATV or dirt bike by replacing the stock cylinder bore and piston with a larger version. This provides more displacement, increased combustion flow, and more torque." Google "139fmb big bore kit" or "k157fmi big bore kit" or "A big bore kit for a 139fmb engine requires a cylinder, piston, crankshaft, head, and gaskets. Some recommend replacing the engine instead of trying to modify the existing one. A 125 cc pit bike engine can be purchased for around $300, and there are also many inexpensive and reliable drop-in replacement engines available." I don't know if it would work but I would prefer the engine swap if it can be fitted.
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