S107 Syma Helicopter tips, repairs and mods.
Here is a quick page of tip and tricks to keep the cheap but oh so flyable S107 helicopter airborne..
1) The "circling the toilet" problem.
Have a problem when lifting off? Does the heli go up ok but "swirl around" before crashing out of control? Do the blades crash into each other? There is a few possibilities and I'll try and address the ones I have found.
A) A turnbuckle off or missing will cause this and is the easiest to fix, they snap right back in place. If missing you can pickup up repair kits off Ebay or Amazon.
B) The most often culprit is this piece- There are two pins off the mainshaft that hold the swashplate in position and if the blades take a hard vertical hit can shear them off. All off the units I have here have had this problem! One lasted as little as a 1/2 hour when one of the kids took a swat at it while another lasted over a month with heavy flight time. If you can hold the mainshaft in place and wiggle the swash plate clockwise and counterclockwise than you have found your problem. If ordering I'd advise getting a few as it seems to be a weak point and will break again. Don't bother trying to replace the whole shaft, just loosen the two screws holding the head onto the shaft and swap the headpiece out. Oh, and Home Depot carries the 000/00 Phillips screwdriver set you will need for just $5
1/2012 update- I ended up ordering a 10 pack of mainshafts off Ebay for $12, clearly the way to go since this is *the* item that always breaks.
C) Balance bar pin too tight- This usually happens after you replace the headpiece, the balance bar will be too tight and the chopper will swirl or blades will clash. Take the mainshaft from the repair kit and use it to hone the bolt opening. It has some knurling on it that works perfect! Just clamp the mainshaft in a pair of vice grips and ream out the balance bar pin opening.
2) Helicopter won't trim.
One of the helicopters was defective out of the box- It would rise just fine but would rotate no matter what. You could fiddle with the trim all you wanted but it would at best still rotate one direction or another. As soon as you touched the main directional control it would wildly spin out of control and crash. We used it for a donor for the other helicopters as sending it back wasn't worth the hassle. I suspect it had a bad circuit board or something with the gyro mechanism.
3) Battery life
One of the helicopters battery has failed just after 2 weeks. At best it will fly for 2 minutes after charging for several hours. I'm just going to replace the battery with a new one that is included in a "master repair kit" for $12
Speaking of batteries, I added a second one from a repair kit to my personal unit, it seems to work fine and has increased the flight time a notable amount. I simply cleaned off some of the insulation from the wires going to the main battery and tapped in the second. A spot of clear tape to hold the battery in and away you go! The flight characteristics don't seem to have changed much and if anything the slight addition of weight seems to make the chopper less "flighty" and more stable than the others.
Some people have used cell phone batteries to replace the main battery, feel free to google about for ideas!
Some sites have mentioned an upgraded tail rotor from Picooz, if I get one I'll post the information here.
Gary