Gas/oil ratio mixtures and oil/grease leakage?

[TwittyMC]

Hey im a new member with a 1996 RM 125. It runs great, starts on the first kick, and is a blast. Two concerns. The previous owner told me to only run it 50:1 (gas/oil mixture) but didnt give a reason why (i cannot get ahold of him anymore). Now i am no mechanic but i was under the impression that 32:1 is standard mixture which is also what the service manual says to run. Could he be running a bigger piston or something? So my first question is what engine mods or changes would make someone want to run a bike 50:1 instead of the suggested amount? My second question. Grease/oil, a deffinite mixture of both, is coming out of my front sprocket. Sometimes a decent little puddle of oil, (but nothing that has affected my level) comes out from behind the front sprocket along with a butt-load of grease. The grease may be from my chain, but there seems like far too much for that to be the case. Could i have a bad seal behind my sprocklet? I just dont know, thats why im here and would appreciate any help on either subjects. Thanks alot

 

[kmccune]

50:1 is way too little oil for your 125, do a search it has to do with the piston speed. Use 32 or 36:1 you may have to rejet, if it was jetted right in the first place. Check the oil in your gear box if oil is leaking from your front sprocket, the seal may be bad, or the sprocket nut may be loose (not sure if it has a nut or a clip holding the sprocket on) Check that oil before you ride, it may be chain lube but better safe then sorry.

 

[MikeT]

50:1 will cause your engine to wear out faster. It will run, but have a lot of excessive wear. Run 32:1 and re-jet if necessary.