RECENT POSTS

40:1 or 50:1?

Status
Not open for further replies.
Joined
May 20, 2007
Messages
8
Likes
0
#1
My 1997 RM 250 has new upper and lower with about 5hrs on it, I been running a 40:1 mix (yamalube) and its spitting oil all over the rear. I was told to try a 50:1 and see how that does, Is this wise on a complete rebuild? What is the least amount of oil per gal. can safely be used?
 
Joined
Mar 26, 2007
Messages
236
Likes
0
#2
The proper way to correct this is to rejet the carburetor. Part of your carb is running rich.

Opinions vary on what is the "correct" gas:oil ratio. It has been shown that less oil isn't really any better for performance. I would go with whatever the service manual says , regardless of what the oil maker says.
 
Joined
Apr 18, 2006
Messages
1,534
Likes
8
#3
What mix was the bike set up before the rebuild?

If you are changing the oil mix to avoid another rebuild then you should check the carburetor jetting to make sure it is okay. Once you get the jetting set properly, stick with the oil/gas mix.

Rod
 
Joined
Oct 21, 2006
Messages
655
Likes
0
#5
change the silencer packing its probly soaked with oil- it will hold in more backpressure

40:1 lean out the jets 2 sizes,check the plug-- tan color is what you want- not black/or wet
 
Joined
Oct 17, 2006
Messages
37
Likes
0
#6
def dont change the mix just to get rid of spitting oil that just fixes the side effect of a bad jetting, i would stick with daleao and run 40 or 32, more oil in the gas actually gives you better perofrmance since it allows the rings to seal better and get better compression
 
Joined
Feb 26, 2007
Messages
187
Likes
0
#7
would you rather seize a piston or Foul Plugs??? I would rather foul plugs.... pretty much any day than seize the piston. Like others have said Jet that sucker. Don't just change the ratio.
 
Joined
Mar 28, 2004
Messages
512
Likes
0
#8
I spun a main bearing on a KTM 250SX running Motul at 50:1.
I guess there is always the possibility that it was just coincidental bearing failure, but I have not run that ratio since.
 
Status
Not open for further replies.