Ryobi 26cc four stroke:
MAS 18X6 Wood = 6300rpm
APC 16X8 composite = 7200rpm

All with stock carb and stock muffler with baffle removed and enlarged outlet.

What's the model number. Is it the new 3rd generation series? Was it a lot of work to convert? Those numbers sound like a typical 2-stroke conversion of the same size, cool. How about inverted flight, any trouble there?

Don't remember the model #. It is the 2nd generation series though. They are all over ebay. Requires a fair amount of work to convert. The mount came from Carr Precision (nice piece of work!). I removed the baffle in the muffler to flow better. I have to see how it will fit on my Rearwin Speedster which is where I want to put it. Seems to run just fine upside down. I may get another at some point just to try some hop up mods. Would like to get one to swing a 18X8 Zinger @ 7000rpm. I'll post some pics in my gallery soon. Busy working on 2 Tecumseh conversions at the moment (49cc & 138cc).

I hear they are heavy though. Does it really come in at 5 lbs.?

I'll have to put mine on the scale. I've got a Quadra 40 in the Speedster now and this feels close in weight.

Hey bdstr, I was digging thru my shed and found a 4-stroke Ryobi that I'd stripped down a few years ago. So I'm here right now looking for information and mounts and parts,etc.

But I do have a tip for you that I'd heard once that may increase the power for you.

As per EPA regulations, fresh air has to be mixed with the exhaust (or vis-versa) to get these little engines to pass smog . Anyway if you pull your carb and your exhaust header off and look very carefully against a bright light thru the ports, you may see a bleeder hole connecting the intake port and the exhaust port. There was one on my engine and I plugged it with JB weld. This mod is supposed to keep the exhaust fumes from "watering" down the fresh intake air. I got distracted before I had a chance to finish the engine conversion and see if my mod worked.

Thanks for the info. I'll take a look and see what's there.

Hi,

I have a GEn 2 4 stroke (plastic sump) and all stock get 6500RPM with a 18x16 Master Airscrew Classic. How did you remove the baffle from the stock muffler without destroying it?

Thanks,
Louis

You have to pry open the crimp around the edge. This is really not worth the trouble. Get a hold of Adam Neat (ANEAT) here on RCU. He's a good guy and can help you out with a straight pipe system (best way to go). These things sound sooooo cool on a straight pipe.

The way I mod the muffler is to use a grider and grind away the crimp, remove the guts and using map gas braze it back together.