31-03-2003, 06:20 PM
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How critical is the oil/petrol ratio for a 2 stroke engine?
(Jon Weaver) wrote:
Hello Jon
JW I imagined that a slightly richer mix would be better than a
JW lean one, so I have made sure that I mix is on the 'rich'
JW side if anything. I figured that if it was too lean, then I
JW stand the risk of seizing the engine and doing real damage.
JW But it is too rich, I would just have too much oil,
JW resulting in more smoke from the exhaust.
JW However, I asked my local lawnmower maintainer about this
JW and was told that it should be spot on 40:1.. To much or too
JW little oil is just as bad for the engine.
Nah, he's talking rubbish. You're right in that rich is better than
lean - when rich the worse you can do is get the plug dirty (and
sometimes foul the carb if VERY rich). When lean they overheat and
eventually sieze.
I run all 2-strokes at 25/1. Yet to have a single problem...
One way you can check that your mixture is correct, and will also
highlight any problem is fuel mixture at the carb.
Run engine for a while in normal use. Remove spark plug and check it.
Light biscuit colour = A1 perfect mixture.
White colour = Too lean, increase mixture at carb.
Black colour = Too much oil or too strong a mixture at carb. Also
happens if you only use the engine for short periods.
--
Simon Avery, Dartmoor, UK Ý http://www.digdilem.org/
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