What petrol to use for dirt bike?

Diesel is same as Kerosene

Your bike takes petrol (or gasoline) All gas is unleaded. Regular gasoline(which is lower price than Super or premium...which are names and maybe bull sperm is put in as the additive, or spit.(it is a secret ingredient)  Maybe it is just the name. We don't know but are willing to pay extra for the unknown B.S.

. I believe the oil companies are rich enough without me GIVING THEM MORE CASH.  It will run on regular grade petrol.  Says in the owner's manual.  Most bikes by this time should have a side tank under the side of the riders seat that holds 1 litre of 2 stroke oil and it auto mixes.  They had them in  1972 so 45 years later yeah I figure you do not have to mix it in a gas can.  (Read your owner's manual first to be sure.)  You MAY have to mix it in a gas can first if the bike does not have a side tank for 2 stroke to be put in. There is nothing you can do about it because  that is the way that bike is. No oil injection system for it.  The KZ series had it so it surprises me that KX does not.

Your owner's manual is your BIBLE for your bike. Different country so you get a different version of bike.  And only use 2 stroke in the gas mix.  Car engine oil does not mix as well or burn as well (it smokes and overheats as it does not lubricate as well either.

2 stroke is 2 stroke whether the picture on the container is for a boat, snowmobile, chainsaw, or weed wacker or motorcycle.  It is the same stuff.

Most have a CR of 7:1, so regular will do.  

   That's  95 RON, what's  called   "premium unleaded", there. But, like any vehicle; if she knocks or  runs on, try a higher octane.  Your 'sickle   might have some carbon in the head  (coked-up). 

   I don't have to remind you to only use actual 2 cycle oil, not just some 30W.

  edit:  Diesel  is Not the "same" as Kerosene, or Lamp -oil. Many additives to increase cetane rating, and it's low-sulfur.  Kero is your Paraffin Oil, similar to 

Jet  A"  jet fuel. Just like Bunker "C" furnace oil is  "similar"  to kero and Diesel; But Not Same..

   Not "all"  Gas  (petrol) is Unleaded. I see  cans of 116 Octane leaded all over drag strips.. The law is, in the US, you may not  put leaded Directly into fuel tank of any vehicle  used on a public road.

    AvGas is 110 octane low lead; no   alcohol.  Anyone may   buy and put leaded gas  in a can at  air strips or race fuel depots. Or buy  cans at motorcycle shops.

Kerosene.            

Regular unleaded.