On Wed, 2 May 2018 01:12:09 +0100, John Rumm
wrote:

On 01/05/2018 19:33, Stephen wrote:
Hello,

Does anyone have anything good or bad to say about the Ryobi expand-it
range?

Not much good IMO
snip

I picked up a 4 stroke power head since it was very cheap in a local
cash and carry (about £70 IIRC). That was pretty crap really. Less
power, and it did not run consistently at all angles. Eventually the
timing drifted so that it would not run reliably or even rev properly.
Tuning did not help, since it seems that the main problem was plastic
components in the timing that wear.

....and on mine the lobe of the plastic cam actually melted. Should
have been a simple fix but parts are not listed.

I only bought it as a lending out tool so as not to have to loan my
working kit. Still have the chainsaw head, hedge cutter head, strimmer
head and extension should anyone want to collect them.

I was interested in it mostly to see how it worked as a small 4 stroke
and it was good enough but not as good as a 2 stroke. Plus the obvious
benefit of not breasting in 2t exhaust (which must be worse then
diesel exhaust surely??),

Interestingly it differed from the Stihl 4mix, we used these in the
pole saws, which are similarly valve operated 4 strokes but they
imbibe a petroil mix which has a parallel path for the crankcase, via
the rocker box and push rod tunnel. This means the big, small end and
piston are lubricated from the oil mist in the crankcase but also as
the piston descends and the inlet valve opens some air:fuel mixture is
forced back and down the intake valve.


AJH