i can tune a 2 stroke fine. how much different is tuneing a four stroke (mag .91 to be exact)?
are the factory needle settings/breakin instructions fine? (14x6 prop)
btw i dont plan on buying (or borrowing) a tach so....please dont tell me i need one
also will cool power 5% (the pink castor/synthetic blend) be fine for break in? i think i can get powermaster 10% at my lhs (idk havnt been their, thats where my friends get their fuel) if i have to.
if this weekend was going to be nice i would have someone break it in for me (at the field). but the weather is looking bad, really windy, last time i went out in the wind, 25mph, my plane flipped off the starting stand, the wind was always changine direction so i couldnt position the plane (gp rapture) to avoid it, and i broke the wing tip and horz. stabilizer (not that bad) easily repairable.
so should i wait for someone to break it in or attempt it myself?


totally off topic
this has been a bad week for me
lost my rc boat (i think it was either signal loss or the radio compartment box came loose (holds the servo's,radio,batt, it was not connected when i found it), so i had no control, either case it smashed into the shore, luckly its repairable w/ no reshaping to do. (ill get a fail safe, should have had one to begin w/)
i retired my first plane (that actually flew), gws slowstick, ever since i put the towerpro motor (from hobbycity) on it is has been flying like s***, the motor works great, but it just doesnt have the umph of a rimfire 35-30-1250 (i had to cut the fuse "stick" (was busted) and move the wing back to get it to balance. not to menton the plane didnt have as much power/weight so it couldnt take the wind).i was flying and a gust of wind fllipped the plane on its back when i was going vert (only about 10 ft off the ground). and i just didnt have the power to pull out of the inside loop form that low and i knew it (i couldnt keep flying upside down either, loose altitude way to fast w/ the motor) so with no other options i pulled back hoping that it could complete the loop in 10 ft. (w/ the rimfire i could do about 3 loops before i would hit the ground, if i WOT it i could actually gain altitude when looping),
well it didnt, nose planted it really bad, the plane survived but i have realized it almost has as much epoxy as foam so it will be retired, motor survived (prop was non existant) but one of my s3114's stripped the small black gear, cost $6.50 for a new set, (does anyone have a broken s3114 that still has the small black gear that they are willing to part with? could get 2 hxt900 for that price). if not ill add that to my shopping cart along w/ another slowstick
and if thats not enough i cut my hand w/ a drill and a mas 14X6 prop (messing w/ my mag 91, just turning it over to check compression, didnt know that a old prop could be used for a steak knife, i thought they were only good epoxy/paint stirrs)

and im mounting this 91 to a 40 sized spad (luckly its very tail heavy w/ a 47 enigne so it will balance fine) for breakin. hopefully this doesnt go on my list of worst days of the week.

Just a thought. if you have a 40 size spad and it's "very" tail heavy with the 47 in the nose then somethin aint right? Was this an ARF or build? As you say putting the 91 in will certainly balance it but be ready on the sticks on takeoff as your going to have lead sled with that big heavy motor to balance out the very heavy tail.

We all have bad days.. very windy few weekends ago.. shouldn't have gone flying but.... 4 star is suited up and ready.. im waiting a bit for the wind to die... doesn't.... 1st sign i should go home - plastic chair blows over onto the plane.. hmmm checks out ok.. 2nd sign - fueling up.. and the fuel line comes off my elec. fuel pump, 3rd sign - on the runway... and the motor dies on me.. (never does that) needless to say i came home with more parts than i brought that day ! stupid stupid stupid!!! As maverick says.. i Know better.. i will never.. never leave my wingman again !!

The 4-stroke is still an internal combustion engine with a carburetor that works prettymuch just liek the one on a 2-stroke so tuning is no different.

Personally, I'd run 15% fuel in it but you can probbaly get by with 10%. I really like the 15% cool power.

It's a SPAD, not a kit or an ARF. Just follow the instructions that came with the engine for break in. The 5% will work just fine but it tends to make it a tougher job to get the low end adjusted correctly. I'm like Chuck, I would run 15% but I have used 5% and 10%, it's just easier for me to get the 15% so I run it in all my glow engines. It's more about the oil content then the nitro when breaking in an engine, 18 to 20%. I run Power Master and the oil is blended with a little castor in the content.

You also will want to use a tach. (for me is a must when ever I am running in any 4 stroker engine)
Do not touch the low idle needle until the engine is completly broken in.

Hi!
Four strokes are exact like any other engine. They are as easy to set without a tach as a two stroke. 5%-15% nitro fuel is ok!

No, that is exactly what it is adviced everywhere to avoid, tune it like a two stroker. Why? There is a huge difference in sound, while in a two stroker you can definitivly know when it is at its maximum revs. just by "ear" in a 4 stroker engine the sound does not make much difference.
The pinch line method used on two strokers tunning is useless when tunning a 4 stroker.
You have to measure your max. constant revs. by using a tach, then you have to richen the mixture and loose about 200 to 300 revs.
I really doubt that you can do that by "ear" or with a simple glimpse.
Is there a better way?

well for the normal person the plane prob isnt that tail heavy for me when i have to add weight to the front to get it to balance its tail heavy (maybe 5oz up front), (thats cause i put the servo's in the back)
i fly it a bit tail heavy, so w/o the weight it should balance fine w/ the 4 stroke

well i tried to get it going today.
after about 30 min of flipping (fuel wouldnt go into the carb when primed, would just fall out onto the floor)
so i decided to flip the engine upside down to prime it. i got it to run, backwards, twice, each for prob 5 seconds before it sputtered to a stop
i think the fuel tank is a little to low, and my fuel lines are at a strange angle (look at included pic, tank about 3 in from motor, carb is a little below the top of the tank)

should i flip the engine over and try again, or could i just get a spinner and use my starter to get it going?
also could i flip the engine backwards to get it to start going in the right direction, like i do on my 2 stroke engines?

Make sure your fuel lines are correct. I've accidentally hooked the vent to the carb and the fuel supply to the muffler once. It would actually start on a full tank but quite after a few seconds.

nope their right