I have an os 51 four stroke mounted on an elder 40. Due to the design of the plane, I cant get to the carb to choke the engine. When the engine is cold, I put my finger on the muffler, flip the prop a couple times and the engine is primed. After i run the engine, I learned the hard (and stupid) way that the muffler gets REALLY hot.. How can I prime the engine after I have ran it?

I fly the O.S. 52 and I never prime it. The first start will take maybe 5 to 10 seconds of cranking with the starter before it fires off. Starts the rest of the day usually kick of within 1 to 2 seconds. Just set the throttle slightly above idle and there realy isn't a need to prime it.

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I always open the throttle to full and crank the engione for a few seconds without powering the glow plug.

Then I back to just above idle, power the glow plug and start it up.

That's for the first flight. After that just power the plug, hit it with the starter and it goes.

Takes a little longer in the cooler months but still no big deal.

I usually dont use an electric starter.. just donl like to lug all the stuff to the field.. should I have a problem starting this engine by hand?

It'll start fine by hand, next time your in the hobby shop you could get fancy and look in the R/C car section, they make a little stopper assembly for priming and killing car engines, just plug the muffler with it, or you could just get a 1/2" dowel and taper the end like a plug, stick that in the muffler and flip a few times. At least you wont burn your finger. I run dubro silicone diverters, so all I do is pinch off the silicone tube and give it a few flips to prime, you'll usually hear the fuel getting sucked into the carb, that's the signal to stop priming and flip it a few more times with your plug out of the muffler and then go ahead and connect the glow driver and flip just once, it usually will always fire.

I understand that carting a starter and a battery to the field requires some sort of effort but it also assists in keeping fingers as far away from engines as possible during the starting process. I have seen several incidents where people insist on hand starting aircraft and have ended up with several stitches in fingers due to prop strike. It is not very nice and potentially very dangerous. At the very least you should have a heavy glove on your hand or use a chicken stick. For me a starter is essential and any plane with a cowling on it also has a remote glow driver fitted as well. The extra $10 is inconsequential when the cost of the plane is tallied up.

One thing I learnt very early on in this hobby after being struck by a Norvel .049 engine for a control line aircraft. Being struck by  a prop hurts and no matter how small they are they can do plenty of damage. Spend the money on a starter and battery and whilst you are at it make sure your aircraft is properly restrained during the start up process. You can save a lot of potential pain with just a little effort

weird, I usualy don't even use an eletric starter on any 4-stroke I have, no need to. After the inital prime, for the first run of the day as long at it wasn't run dry I've never had a problem, fuel it up just hook the inginter up and smack the back of the prop with my hand. just gotta be quick. When I'm lazy it has never taken more than one lundge through the compression stroke with the eletric starter. I have to admit thats from expreiance with my engines and getting a great idle setting.

For a new engine I would LUG all your equipment to the feild, once it's broken in and running reliably and you know the motor, then leave your junk at home and hand start it, though a chicken stick is advisable

If you hate hauling a bunch of stuff to the feild then these are for you. I've alway hated the feild box and power panel thing, it just sucks

b and p starter the starter is spendy and probably not justifyable to many first time flyers but it is the best I've seen and starts everything from .049s to 1.8's

and hot shot

owned allot of igniters this one is the only one I ever liked.

Now alls I really need to bring to the feild is a small tote with some tools a pump and a some fuel.

I don't prime anything after the first run of the day. There should be enough fuel residue to fire the engine up after you've run it. It really doesn't take much fuel to get the engine started, thus many people over prime their engines.

Remove the vent line from the muffler, plug in your fuel pump and pump fuel into the vent line.

That will force fuel into the carb from the feed line.

Prime the engine, grab the spinner, back snap and it fires, after the first run of the day Iusually don't have to prime to get them to fire. On YS engines I flip the prop until Iget a squishing sound of fuel to the carb and pressure into the tankthen attach the glow driver and give the spinner a back snap, they fire up. Usually no prime needed after the first run of the day.

The simple soulution is to put a small piece of silicon exhaust deflector on the muffler exhaust pipe. That is what I have done.

When starting a hot engine it is usually not necessary to prime it, flipping it over smartly should be enough.
There is no need to use an electric starter, but I strongly recommend that you use a chicken stick

Or you could just wait the few extra minutes for the muffler to cool off

Brad

Too simple!!

Ioften just grab a piece of paper towel or something and hold it over the muffler, since Iusually have one handy for fuel spills. Protects my hand from the heat and works almost as well.