petrol oil ratio

[Hadley]

Hi,
Iv'e got an 87 rm125, what petrol to oil ratio should I run it at? 30:1?
also, whats a real good oil to use for the old 2stroke?
Cheers.

[WRT]

Dunno what the ratio should be, but Motul 800 is a fantastic oil, and will let you run pretty lean ratios.

Try to track down your manual to see what ratio to run, 30:1 is probably a pretty safe bet. I have a '01 CR250 and normally run a lot leaner than that, between 40-50:1, depending on my mood

[Cary]

My '90 KX250 ran 33:1

[cheese]

I run 40:1 on my RM on the Motul800, can I go to 50:1?

[Wellyman]

I run 40:1 on my RM on the Motul800, can I go to 50:1?

You should be ok on 50:1 I would say. And yes Motul makes the best oils, I only use Motul really.
WM

[XTC]

You should be ok on 50:1 I would say. And yes Motul makes the best oils, I only use Motul really.
WM

That's quite a claim! Have you got scientific evidence to back this up or is it just your opinion?

[rogson]

People confuse fuel/oil ratio with the terms lean and rich.
If your bike is running rich the fuel to air ratio is too high. No amount of fiddling with the fuel/oil ratio will cure that - you need to change the jetting.
Reverse scenario with a bike running lean.

Getting the jetting correct has the biggest impact on engine performance and longevity. The oil/fuel ratio is a secondary factor.