20:1 or 32:1

[mxmatthew]

40:1 or 32:1

i bought my bike used an the previous owner said that he used 20:1 premix with yamalube so that has been what i'm using although in the owners manual it says to mix it 32:1. The plugs either a nice tan color or a little wet around the edges when trail riding so it doesnt look as if its running too lean. Will this hurt the engine at all or cause any premature wear even though the plug looks right?

 

[pace]

I'd start with the manual recommendation. It seems like 20:1 is an awfully rich premix / lean fuel mixture. I often go a little leaner on premix than what's in the manual in fact (36:1 - 40:1).

-Pace

 

[mxmatthew]

ugh sorry i dont know what i was thinking i meant 40:1. lol how would 20:1 wear your engine quicker lol. what do u think about the 40:1?

 

[nephron]

What are you riding?

 

[motometal]

the only real advantage of using less oill is that there is less chance of plug fouling.

 

[Mike's 2003 YZ250]

MotoMeal, not trying to sound like Im argueing or anything and Im sure you know more than me on this subject, but is that 100% true? I thought the less oil you used, the richer the air-fuel ratio became, and the richer it became, the more likely you were to foul a plug? It seems some guys on here think like you and some think like me, well I think the way I do from reading other guys replies on here. I am just trying to learn the proper way, thats all. :cool: Mike :)

 

[motometal]

yes and no. Changing ratio should not be used as a method of adjusting jetting. You are correct that it does affect jetting, the specific effect depends on many variables including the viscosity of your favorite premix oil.

Oil protects your engine. It also helps it make more power. If you want to learn more, feel free to do a search.

by the way, never assume that I know more than you about anything. I might be a complete idiot. Not that there's anything wrong with that.

 

[john3_16]

I would stick with 32:1 and jet it correctly....You could run a very rich oil/fuel ratio(20:1 verses 32:1) and still damage your engine with incorrect carburator settings....If your jetting is stock more than likely you will be fine with 32:1....

 

[mxmatthew]

well the smartest thing to do is probably go to 32:1 but i'm kind of reluctant to because it took forever to jet correctly, it fouled plugs like crazy. It also has a different carbuerator, a flat slide, because of fouling plugs that no one could figure out.

I ride a bit of everything, mx, woods, offroad-enduro type stuff. I probably have about 25 hours on it since the last top end rebuild, no imminent problems but i havnt inspected the piston or anything. Im just happy that i can finally ride it for more than 20 minutes without fouling a plug.