Hi all;
I have an older OS 35FP that I'd like to return to service. It's still loose and looks to be clean, however I neglected to do anything special when I last ran it, (~ 8 yrs). It's still in the plane attached to the tank.

Should I do anything other than fuel it and attempt to start? Should I remove the tank and clean it or will the new fuel clean it?

It was a great running motor.

Thanks!

I would clean the tank. Also, make sure nothing feels "rusty" or sticky. If in doubt I would pull the backplate and check. Loose "stuff" can destroy an engine fairly quickly.

Clean out the needle valve.

I never take apart an engine unless I have too. (too much work and you run the risk of fouling something up)

My solution to old gummy engine is to get a helper (two person job), remove the glow plug, fill the tank with clean fuel, open the throttle full, place a finger over the carburator air intake and spin the engine with an electric starter.

As the starter spins, fuel is forced through the entire system and comes gushing out of the glow plug hole (wear safety glasses). The initial spray will be a redish orange, as the gunk is washed out it will become clear. Once the spray is clear put the glow plug in and start the engine.

If this doesn't work; then consider taking the engine apart to look for rust etc.

Good luck!

Clean the tank for sure.

If you can take it out, do it. Rubber stoppers dry out and split. Fuel tubing inside splits. And brass clunks turn to fuzzy green blobs. And, oh yeah, the alcohol and nitro in the fuel wick off but the oil just congeals.

Just a couple of years? maybe not all those horrors. But a couple of minutes of maintenance done with no time pressure beats the heck out of trying to figure out why an engine won't start with somebody waiting for the pin and the sun beating down and one or two necessary tools back at the house.

Thanks all, here's what happened:

I removed the motor from the plane, (it hadn't been run for at least 8 years!!). Put it on my test stand. Removed the needle, (everything clear). Couldn't see any rust or gunk in the port or carb. Fueled the test stand tank, installed a new plug and it fired right off!!!
This is one amazing little engine...always was.

Now I'm waiting for a new Futaba flight pack and I'll fly this plane again. I'm putting in a new tank, you were right, the lines and stopper were shot.

By the way, the plane is called a Terrier and I built it years ago from plans ordered from RCM. It is a 25 - 35 lightweight sport aerobatic job and it flies super...lots of fun. I just hope I can still see it with my older eyes. I like 'em really big these days.

Thanks again!
CB