Hey, I just picked up a poulan 42cc engine for $10. I need a new jug, but I know where to get parts. I have a question about the intake design. On mine, it has an extra port above the carb with a butterfly valve. It only opens at WOT and is plumed to the airfilter. Maybe a recirculation valve? The piston also has ports, that lead to the transfer ports. I also noticed that when the exhaust port is open, this extra port is also open about half way. In order to use this engine, does it have to have this extra port. I was hoping that i could just block it off, and use a different carb. I am going to take some pics with my phone, and put them on here.

Does that engine by chance say Zenoah on the case or cylinder anywhere?

no it doesnt, it just has the part numbers

Also, do you guys think it would be a better idea to order a 42cc jug off a different saw. (one that uses a standard intake/carb) I looked up the parts, and the standard jugs are a bit cheaper, and have a chrome plating on the cylinder. The replacement for this one, is a non plated cylinder.

I am thinking of making a plate to block the extra port off, and using a stock jug. Just for the sake of knowing, can someone provide me with a bore measurement and maybe a pic (intake side) of their 42cc engine. I am wanting to order the parts soon so I can test this engine out. It also looks like I need some new seals/bearings. I think that is what killed this engine. The seal started leaking due to crap building up on the seal and the engine injested dirt and other crap, scoring the jug all to hell. The piston is also scored, but I dont think its too serious.

Do a search here for info on that engine. Seems like someone else encountered one and closed the upper port off and had good luck with the engine, but I can't swear to it. I have one of that type, but it is in a chain saw that I don't intend to convert as I need it as a chain saw.

AV8TOR

Instead of making a new plate to block off extra port....just make a new gasket with no holes that line up with the ports you want to block off. Good Luck Capt,n

I just spent over 2 hours searching. There is alot of info on 42cc poulans, and pics too. But none that look like mine. Can someone with a 42cc with a normal intake please provide some bore measurements? And possibly the model number of the saw it came out of? On the parts lookup, most of the engines listed are with the goofy intake. I would just close it off, and try it, but from some of the pics i saw, the intake ports look bigger than the one on my engine.

The reason i was asking if it was laballed zenoah was billzair,here in this forum,had a 40cc something with the same style port on it.
It was either a poulan or ryobi.But iot had zenoah on the side of cylinder.
Ill go see if i can find the post.I belive its on the 3rd or 4th page by now.
Just look for billzairs name.

Thanks alot for that info. Its funny, I didnt even look at that post, cause at the time, I thought I would never build a plane that would need a chainsaw engine. From the one post, it states that the poulans (like mine) get a 200rpm increase by blocking the ports off. I think i might order the new jug right away. Im kinda excited about geting this thing going now.

I have acouple of the 42 poulan's and I think the piston is also different so you would also need to order a piston and ring my old style is together so i can't provide measurements but I just ordered new rings form Frank Bowman He should have all the measurements.

Check out Brillelli. They already have what you need I believe.
brillellicustoms.com