Hi Guy's, Can anyone tell me the difference between the 725R and the 780R? I am told they are both 31cc. Thanks.

John,
They appear to both have removable flywheel shrouds and single rings. The other differences they have are the compression relief slots above the transfer passages. They are both long shaft clutch types.

Dave



http://outdoordistributors.com/pdf/R...-102066940.pdf

Thanks Dave, I thought the 725R was the dual ring engine? Which model Ryobi 31cc engine has two rings? I'll have to look at the one I have now to make sure.

John,
I don't know what models are dual ring. All of the parts breakdowns just list piston assembly. I have two long and one short shaft. Both long shaft have single ring and grooves. Maybe a repair shop would know the models or part numbers.

Dave

Dave, Just got off the phone with MTD tech support and they say the Ryobi 725R and 780R are the same engine. I was also told thet prior to 2000 they used single rings and after that they changed to two rings.

John,
Thats interesting. I guess if you gather enough used engines from repair shops etc, you should be able the put togather a few good ones without grooves.

Dave