Put a bigger carb on it. I replaced the stock carb with one from a Mac chainsaw. I think it was a Walbro WT 348. It was the exact size venturi as the opening in the backplate.

Bend the reed stop on the backplate. Bend it out untill it just barely clears the crank pin. This will let more fuel in.

Clean up the transfer ports on the cylinder with a Dremel. Anything you can do to smooth out the fuel transfer. Just don't remove too much material unnecessarily. That will INCREASE the swept volume in the crankcase and actually slow down the fuel/air mixture going through the case and into the cylinder===BAD. If anything- you want the fuel running through the case at the same speed as stock or faster. DECREASE crankcase size--STUFF IT-- to make the charge go faster through the case. Never actually done it myself, but it's supposed to work VERY WELL.

Get an electronic ignition for that sucker. It's pricey, but it will make your engine lighter and it wil "spool up" faster when it's not turning up that extra 2lbs. of magneto weight. I used a synchrospark ign. on mine. TOTALLY not necessary on such a small engine- but it idled at 1300-1500RPM and throttle up was really nice. Hand starting was a breeze. 2 flips on choke and then 2 more to start it.

Generally, if you use a BIGGER carb-- then you'll be spinning a SMALLER prop at HIGHER RPM. And if you use a SMALL carb- then you can turn a BIG prop at lower RPM.

Sounds arse backwards, but if you think about it-- it's true. In order to get a bigger carb to work properly- then it needs to have a lot of air moving through it to pull the fuel in at the right mixtures. That means using a small prop and letting the engine rev up more--7500--8000RPM or so.

Using a smaller carb will actually have the engine turning slower with a big prop because the engine will suck enough air through the small carb at lower RPM to make that carb work fine. So put a big prop on the small carb and swing it at 6500--7000RPM.

Big carb and big prop--- waste of time. Engine won't suck the gas in right and it will just generally be a P.I.T.A.

Your engine can only suck so much air through it. You need to match your props and carbs to achieve the desired effect-- i.e. RPM and thrust desired for a given prop size.

I was using a stock carb to start out with, but too small prop. I had a 16-8 on it and it ran like crap. It was turning 7800RPM- but running out of fuel. I couldn't open the needles enough to feed it the gas it wanted. So I switched to an 18-8 and it slowed down to 6400RPM and ran like a top.

After I switched to the bigger carb, I went down in prop size again to let the engine rev up and suck plenty of air through that big venturi. It was ripping along at 8000RPM with a 16-10. Engine was happy as a clam on 40:1 mix and needles were adjusted to normal positions, not all the way out as it was when I initially started.

Increasing the RPM of the engine gets all the air moving around fatser and increases the vacuum at the intake. You need the increased vacuum to get the big carb to work right.

Lowering the RPM slows it all down- but still enough vacuum and suction to make the stock carb work right at those RPM.

Gassers are torquers. They love to run under high loads and grunt along with no problems.

Just a few ideas to mill around with. These are just my opinions and personal experiences with this particular engine. Others might call me crazy- but thats how I got the most out of my Ryobi.