It works even better on .40-.50 size engines... because they are less expensive when something goes wrong...
On smaller engines you could take the exhaust duration up to 165-167°... this will make 'em rev up to 20000 rpm.
But remember this: sport engines have an exhaust timing of about 150°... if you take 'em past 155-157° they will not run well without a pipe... an engine timed at 160° or more will be crap without a pipe...
You can also increase the intake timing of the crank. 5° or so should be enough to start with. You will notice that the engine will start to spit raw fuel out of the carb at part throttle after you have done this. That doesn't matter, as it is the full throttle breathing that counts.
Grind the scavenging ports in the sleeve so they point upwards about 30°.
The exhaust port should be grinded so it points downwards.
This is also to maximise flow.
If the conrod is a rectangular piece of metal (they mostly are), grind away until you have a nice streamlined shape. Don't overdo this, because you can guess what will happen if you take too much meat off...
