Hi, just a bit of info, a flyer I now had a new ZDZ 40 which he flew for a few flights and the sulivian gas stopper came apart, piecies got into the carb, leaned it out and seized the engine. Sulivian said that some of the gas in Ca. eats up the stoppers so they sent him a few different ones and told him to soak them in the gas he was using and see which ones it didn't effect, haven't talked to him lately so don't kow what the outcome was. Anyway there maybe gas in outher states that have the same effect. Soak your new stoppers in the gas your using before using them, better safe than sorry. I had the same problem with a Black Sulivian stopper on my Ultimate with a RCS140, didn't seize the engine but the stopper just came apart in the tank, filter stopped it from getting to the engine.
Jim

Yep, this problem's been around for awhile....I lost a Ziroli P40 for the same reason. Engine died as a result of a dissolved brown stopper.
I don't know about the "different gasoline" part of the story as this is the first I've heard of it. I heard the problem was related to manufacturing of the stoppers.

The first I heard of this problem was way back in 95/96 time-frame.

I lost my P40 a couple of years after that, believing that the problem had been resolved. Apparently it's not!

My bench testing / break-in was done with Texaco fuel and Pennzoil 2 cycle oil. The next gallon is Shell gasoline and Belray H1R 2 cycle oil. Oddly enough this problem started with the Shell / Belray combo. Any similarities??

I was working in the small engine business in the mid '80 when "oxegenated" fuek started hitting market. Some used Ethanol, methenol, and TCBE's. You would not believe what it would do to some of the rubber fittings and lines in chainsaws and trimmers. Some lines would just turn to "goo", others would expand and fall off the fittings. Differant fuels and differant brands of equipment all did differant things.
Checking the stopper with the fuel you use may be sound advice.