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Keep your hands away from props, kids

#27
That is why on 4 strokes to double nut them locking the two nuts together better chance of not having the prop come off. Normally backfire comes from being a bit to lean only happens on the 4 strokes at least hard enough to throw the prop..
I've had backfires happen even when they're blubbery rich, I think it's just the nature of large boar glow fourstroks. But you're right, fourstroks have been the only ones to throw a nut in my experience, and my supertiger kicks pretty hard when it's angry. So far I've kept it fairly happy though!
 

JennyC6

Elite member
#31
How about having an engine cutoff switch on your controller? Don't turn the switch till your ready to fly.
That's the norm. The trainer switch is usually used for this, just pulls the carb shut to kill the engine. The engine cannot randomly start like an electric motor so you are 100% perfectly safe with the kill being a momentary switch like that.
Never done that one personally, but I’ve seen videos.
My OS FS-70 Surpass is so bad about it that I actually take advantage of it. When I start that engine I prime it heavily, give it a few notches above idle, roll it past compression but not far enough to open the exhaust valve, then I turn the on-board glow driver on and flip it backwards with a chicken stick.

One flip start every single time, without fail. Busts right off. If I try to flip it the correct direction it will try its damndest to break my wrist but if I flip it backwards it just shrugs and flashes up.

None of my Saitos have ever done this but I also don't have any particularly large saitos. I have an FA-90TS but it's no torquier than my FA-40 or FA-45 MkII since it's basically two FA-45 cylinders on one crankshaft.

That is why on 4 strokes to double nut them locking the two nuts together better chance of not having the prop come off. Normally backfire comes from being a bit to lean only happens on the 4 strokes at least hard enough to throw the prop..
I have had my 46AX's spit a prop a couple times too. It's rarer with 2-cycles because they don't make as much torque but they can do it.

You haven't experienced a backfire until you've handproped a Saito lol
The worst backfire I ever had was an OS FS120 Surpass. I was chicken stick starting it and it kicked back so roughly it SHATTERED a pristine 14-6 wood prop.
 

PsyBorg

Wake up! Time to fly!
#32
The worst backfire I ever had was an OS FS120 Surpass. I was chicken stick starting it and it kicked back so roughly it SHATTERED a pristine 14-6 wood prop.
I watched a guy back in the late 70's break 2 fingers and tear ligaments in his hand using a hi torque electric starter on one of the new outboard boat motors that he was trying to do break in run ups on. He was busy yakkin about his new toy and I guess was only half heartedly holding the starter when it kicked back on him. Folded two fingers backwards as the starter flew out of his hand. Not sure why he had some sort of slotted style cup instead of one of the rubber style ones on most starters. I didn't know much about that stuff back then.