Just to clear up a couple of incorrect items.
1) If your rings are worn it will not cuase Crankcase oil (Transmission is totally seperate) to enter the cylinder. The bike will only loose power and you will get what is called blow-by. When the Fuel/Oil mixture enters the cylinder and the rings and piston are worn the mixture will try to escape past the piston and rings.
2) The Crankcase (transmission) has its own oil which lubricates the gearbox and clutch plates. It is not in any way part of the top-end lubrication. The only way the Crankcase oil will enter the cylinder is if you have a blown crank seal. If a crankseal is blown, vacume will draw oil into the cylinder from the transmission and cause excessive smoke. An easy way to check for a blown crank seal is to have the exact amount of oil that the bike requires for the gearbox (04 RM-250 calls for 750 ml). Once you have that exact amount you can run the bike for about 10 minutes then drain the oil and measure the amount. It would be a significant amount lost if a seal is bad.
3) Use the best 2 stroke Pre-Mix oil you can afford. The cheaper oils cuase more carbon build up and more plug fouling. Modern Synthetic 2T limits carbon build up and has better lubricating properties that help extend the life of the top end. You pay more for the good oil but in my opinion it is definatly worth the extra exspence.
In my RM 250 I run Motul fully synthetic at 50:1 and rejetted my carbs accordingly to my motor spec. (Porting, Pro Circuit Pipe, Boyesen Reeds, Cam 2 fuel)
1) If your rings are worn it will not cuase Crankcase oil (Transmission is totally seperate) to enter the cylinder. The bike will only loose power and you will get what is called blow-by. When the Fuel/Oil mixture enters the cylinder and the rings and piston are worn the mixture will try to escape past the piston and rings.
2) The Crankcase (transmission) has its own oil which lubricates the gearbox and clutch plates. It is not in any way part of the top-end lubrication. The only way the Crankcase oil will enter the cylinder is if you have a blown crank seal. If a crankseal is blown, vacume will draw oil into the cylinder from the transmission and cause excessive smoke. An easy way to check for a blown crank seal is to have the exact amount of oil that the bike requires for the gearbox (04 RM-250 calls for 750 ml). Once you have that exact amount you can run the bike for about 10 minutes then drain the oil and measure the amount. It would be a significant amount lost if a seal is bad.
3) Use the best 2 stroke Pre-Mix oil you can afford. The cheaper oils cuase more carbon build up and more plug fouling. Modern Synthetic 2T limits carbon build up and has better lubricating properties that help extend the life of the top end. You pay more for the good oil but in my opinion it is definatly worth the extra exspence.
In my RM 250 I run Motul fully synthetic at 50:1 and rejetted my carbs accordingly to my motor spec. (Porting, Pro Circuit Pipe, Boyesen Reeds, Cam 2 fuel)
