Sprocket Question

[gazza2003au]

i have a nitrous atomik bike it was a YX150 with a thin front sprocket 20mm i replaced the motor with a lifan 125cc which has a thick front sprocket and is 17mm can someone tell me weather the skinny chain/sprockets are 420 or 428? as i need to get the correct front skinny 20mm sprocket to suit my chain and rear sprocket

cheers guys

 

[mattbombers]

428 is the thicker sprocket 420 the smaller, you can get both front sprockets in 17 or 20 mm shafts

 

[gazza2003au]

428 is the thicker sprocket 420 the smaller, you can get both front sprockets in 17 or 20 mm shafts

thanks heaps mate much appreciated