I have learned the Homelite 30 cc is now the Ryobi 30 series. Rated 1 HP, available long shaft w/clutch from Home Depot for $100.
Barrel carb and plastic back plate. This is the curved shaft, split boom trimmer. Looks like a good entry level boat engine.

I've got one of these. Runs pretty good.

I have been examining the differences in the two engines. The 25cc uses a straight bypass port and the 30cc uses a windowed piston to make up for the restriction in the ports. It is possible the 25 can be reworked to exceed the capabilities of the 30. The port timing on the 30 is also different from the 25. The advantage of the 30 would be more torque at lower speed.

I just dismantled and examined a new Ryobi 30. Externally they appear the same as the Homelite but there are several internal improvements. The most noticable being the transfer ports are now split and aimed. This should improve performance considerably. This engine appears to have potential, it would be nice if someone would offer a domed piston and steel rod for performance use.

I think the ports are split and aimed but the overall surface area is less?

The port volume has been reduced and as a result the velocity has increased. Because of the windows in the piston, I suspect the overall efficiency has been improved. I noticed on the sticker it is CARB approved. The exhaust produces almost no smoke and in the old 25 the same fuel smokes profusely.
Before I test this engine, I will match and contour the crankcase flange to the cylinder, knife edge the port divider and contour the windows in the piston. This should greatly increase flow through the bypass ports. It is amazing how much flow is increased by just knocking off the rough spots. A noticable power increase can be seen by putting a high polish on the piston top.

Update;
I have completely dismantled and examined the Ryobi 30. The transfer ports are similar to Stihl, the new piston uses steel rail rings (less subject to ring flutter at high RPM), the new crankcase has a wider flange to accomodate the new ports but the bore is still the 25cc pattern. The tuners will have a ball with this one, the transfer port area is probably twice that of the old one but is blocked at the crankcase flange. The ports can be extended into the crankcase so they can flow from the bottom as well as through the piston. The piston windows have sharp edges at the entrance and can be contoured to improve flow. It will be interesting to find out just what this engine is capable of. The port timing is very mild and there is a lot of room for improvement. The stock muffler is packed with wire so there is no open chamber. I don't think the new cylinder can be used on the old crankcase without chancing leakage at the ports. I did not mike the bore to see if the pistons are interchangable.

Hi bryan,

How much does it weigh? Can you please post some pics of the transfer setup? From your description it looks like an easy 6 to 7 hp could be made with the right setup.

Wish I had something like this...All I get is two transfers and a lousy piston-ported intake.

I don't have a scale that will weigh it accurately but the info is available from Carr. I am using battery CDI to keep down weight and keep the engine compact. I don't have the ability to post pics at this time but the porting is impressive. The ports nearest the exhaust
are very large and should be extended into the crankcase. With the proper pipe I also think this engine can get into the 5-7 hp range.
It will require matching the crankcase to the cylinder and judicious porting. I think the secret is moderation.

I have built race engines in the past that broke track records just before they exploded.

My long shaft engine with crankcase lightened to the max, less prop hub and exhaust, appears to weigh approximately one kilo.