TB 138cc Big Bore Kit – 125cc 54x54mm 14mm pin Chinese engines
138cc (57mm) Bore Kit for Chinese 125cc Engines with Big Valve Cylinder Heads (Lifan, V2, etc):
– 57x69mm cylinder with steel liner
– High compression large dome 57mm piston with rings, 14mm pin, & clips
– Head gasket kit
This will make a very nice difference in performance over your stock setup. Additionally, it is a very quick and easy upgrade as it does not require case boring. We found the right level of compression for increased performance while also keeping reliability in mind. The 138cc bore kit includes a 57mm bore cylinder, light weight high revving piston and a head gasket kit. Bolt on power!
Important Note: This kit will only work on Chinese/Lifan style 125cc engines with a 69mm cylinder (base to Deck), 54mm stroke, 14mm piston wrist pin, and clutch basket is on the crankshaft. Furthermore you need to compare the OEM cylinder pattern to this PDF in our tech section – TBW1608 Bolt Pattern 138cc Big Bore kits. There are so many Chinese brands/models that you absolutely need to know your stroke and piston wrist pin size. Unfortunately, we are unable to tell you what you have based on a brand name as there are so many unknown Chinese brands. This kit is also recommended for use only with big valve heads such as the common Lifan head with 27/23mm valves or our V2 Race Head for Chinese engines.
Installation Notes: Don’t use the original o-rings between the head and cylinder (not needed) but do use the large o-ring at the bottom of the cylinder between the cylinder and the engine case at the oil return.