I purchased this 20mm Main Jet Kit for a Kehin - PC 10F Carburetor that came off a 1980 Honda XR-80 dirtbike. The main jets are the same for this 20mm carburetor as are many others on the market. The main jets in this kit are Chinese made & not OEM Kehin carburetor main jets, but I had no problems what so ever with them & they are made out of good quality brass. I used the Keihin PC 10F carburetor for a TBParts - 88cc XR/CRF-70 stock cylinder head Big-Bore kit that I installed on a 2002 Honda XR-70R engine for a friend. I had no problems getting the engine tuned & jetted correctly with this 20mm Carburetor Main Jet Kit. Plus, where are you going to find these 6-Main Jets for only $10.00 at besides here at TBoltUSA? I would recommend this 20mm Carburetor Main Jet Kit to anyone that needs them to get there engine running perfectly. These are worth every single penny & then some.