I started flying giant scale planes about a year ago and use gas engines for them. In a sense I am new to gas engines eventhough I have been using glow engines for years.

I have a Fuji 50cc, 3W 60cc and a Zdz 60cc.

My problem is that I fly gas engines for a month and than my glow planes for a couple of months and than back to gas. What I find is that each time I store my gas planes for a month or two it would not start. Each time the problem is the carb is blocked and does not draw the fuel. I than have to dismental the carb and clean it before the engine will start.

This has happen may times to my Fuji and 3W engines. It seems that the old fuel left in the carb hardens and clogs the carb.

Is this correct? How do I avoid this happening? Is there "after run oil" that you can put in the carb, like we have with glow engines?

I know about tricks and tips to maintain and run my glow engines but I hope you all can give me tips on how to maintain and run gas engines. Thanks

I've hever had this problem in flying gas engines for about 10 years. Gasoline here in the USA doesn't have any additives that would "harden" and clog the carb. I'm quite at a loss to explain your problem, but I'll suggest the gas you're using may be impure and/or dirty. Be sure you filter the gas when filling your tank. I use two filters in the gas can supply line, and two in the line from the tank to the carb. If possible, do not use gas with ethanol or any other additives. Gasoline DOES get old and you should use only fresh gas. If you use the gas that's been sitting around in the can since your last flight, that may be part of your problem.

Good luck with it.

Dr.1

I always run the gas out of my engine every time I am through flying it for the day. That way if I don't make it back to the field for a while the gas doesn't gum up the carb and it starts right up. Hope you can use this info.

If you use a filter at the pick up in the gas can, you will weed out a lot of junk that inevitably lays in the bottom of the fuel can.
A lot of folks have eliminated the screen in the Walbro carb and while the screen does pick up stuff, most of it would have blown through the carb anyway.
I am always surprised at the junk floating around on the bottom of the gas can and always wonder where the heck it came from.

3dbob

You have a problem that used to be pretty common with weed eaters and chain saws here in the 'States. Some years back if you failed to run the carbs dry and flush them with alcohol prior to a seasons' storage the same thing would happen, along with the rubber tip on the needle rotting away.

Flush the carb with isopropel (rubbing) alcohol just before you are going to store the plane for a period of time. Just obtain the easy, over the counter stuff and it will work fine.

Pat

Can the problem be due to the oil additive that I put in? What is the best brand to use?

Just use a good quality 2 stroke oil. I've used Yamalube and Amsoil, and I like both. A synthetic oil will burn cleaner and leave less residue on your plane. Follow the recommended mixing ratio.

Dr.1

You might want to try this stuff.

http://www.goldeagle.com/sta-bil/index.htm

Stomaper,

"Stabil" looks interesting. I think my old fuel is gumming up the carb.

Aspen fuel will not gum up, since it is not made up of multi-destillates and residues.
It is premixed at 1:50 using ISO-L-EGD (jaso FD) class synthetic two stroke oil
[link]http://www.aspen.se/Templates/standard1.asp?PN=106129[/link]