Pit bikes, quad bikes and mini motos use a variety different chain sizes. You will need to bear in mind your current chain size when replacing chains or sprockets.

Please use the diagram below to check the dimensions of your chain:

Chain size diagram

I have my old chain, but how do I know which type of chain I need to replace it with?

 

  • If your chain has a pitch of 6mm you will need a 6mm chain
  • If your chain has a pitch of 8mm you will need an 8mm chain
  • If your chain has a pitch of 13mm and a width of 15mm you will need a 420 chain
  • If your chain has a pitch of 13mm and a width of 17mm you will need a 428 chain
  • If your chain has a pitch of 13mm and a width of 19mm you will need a 428H chain
  • If your chain has a pitch of 16mm and a width of 18mm you will need a 520 chain
  • If your chain has a pitch of 16mm and a width of 20 / 22mm you will need a 530 / 50H chain

 

I haven’t got my old chain, how do I work out what type of chain I need?


Although your chain may be missing, the likelihood is that you still have the sprockets attached to the engine and back wheel. Use the diagram to see how to get find out your sprocket size (according to its width). Then see the points below to identify the chain type you need.

A sprocket’s roller seat can also be called the width in most cases. The width refers to a normal chain link, not the width of the split link, which will be wider.

  • If your sprocket’s roller seat width equals 3mm you will need a 6mm chain
  • If your sprocket’s roller seat width equals 4mm you will need an 8mm chain
  • If your sprocket’s roller seat width equals 6mm you will need a 420 chain
  • If your sprocket’s roller seat width equals 7mm you will need a 428 chain
  • If your sprocket’s roller seat width equals 8mm you will need a 50H or a 530 chain (these two chains are exactly the same, except 50H has a 2mm greater width / pin length)

 

I haven’t got my old chain, how do I work out how many links I need?


To work out the chain length you need, use string or sticky tape to stretch around the two sprockets, then measure the length. Reduce the length by approx 2cm to account for the fact that the chain sits inside the sprockets.

After you have worked out what pitch, width and length you need (see above), use the formula table below to work out how many links you need: Take the length of the chain in centimeters then divide it by whichever formulae is applicable to your machine type (see below). Simply round the number up or down to the nearest whole number.

  • If you need a 6mm Mini Moto chain, divide the circumference in centimeters by 1.29
  • If you need an 8mm Midi Moto chain, divide the circumference in centimeters by 1.61
  • If you need a pit bike 420, 428 or 428H chain, divide the circumference in centimeters by 2.62
  • If you need a quad 50H, 520 or 530 chain, divide the circumference in centimeters by 3.28


If you are in any doubt, remember we are here to help. Please email sales@petrolscooter.co.uk or phone Sales on 02476 398085.

All dimensions are stated in millimeters. The width refers to a normal chain link, not the width of the split link, which will be wider.