Hello,
I recently upgraded to an OS .75 and my original starter is not strong enough to turn the prop. I tried a tower hobbies havy duty starter and that won't do the trick either. What is a good heavy duty starter that will turn the big engines? I also have a Magnum .90 FS so it will need to turn that as well.
Thanks!
Darin

Hello Darinself,

I dont think you really need a heavy duty start to start that engine. what I think is happening is 1 you may be flooding the engine when your fueling which makes it hard to turn or 2 its still a new engine so there is alot of compression and 3 make sure your 12 V battery is fully charged .. hey u never know... anyway here is a trick you can do.

Fuel that engine up. (without putting the glow iginiter on ) <~~ read that again very important. I would turn the prop by hand for a few turns, this sometime's loosens the engine up. I would then try to start her up with the starter. If that doesent work, Use the chicken stick a few times and then try to use the starter. Give those a try it should work. Hope i helped.

We use the Tower Hobbies heavy duty starter on .61 two strokes and .91 four strokes all the time. We have the regular 7ah field box batteries. If the battery is fully charged it works great. When the battery starts to get low, it has a harder time spinning the engines.

If it's a battery voltage (or amperage) issue, getting a different starter will not help.

Two things.

One, you need a "running" start for your starter. Meaning start the starter a second before you you apply it to the prop. You may also need to switch the prop adaptor around on your starter to accomplish a better grip.

Second, like NJAIRSTRIKE said, you might need to prime the engine first. Again DO NOT USE THE GLOW PLUG BATTERY AT THIS TIME. Without the glow plug battery attached, open your trottle full and place your finger over the carb and carefully flick the prop until you see or feel fuel going through the carb. I find it helps to turn the prop one revo to the right to choke the engine after this is accomplished. Now place the battery back on the glow plug and crank her up. Should have no problem.

All good points.. but one more little thing. Rotate the prop backwards by hand until it reaches the reverse compression stroke. Not all the way through, just to the beginning of resistance from compression. Then give it the running start approach. This gives the prop a tad bit of momentum needed to get past the first compression stroke and it will start just fine. I have the 46 SF, 50 SF, 75 AX, and 1.20 AX and use the same starter and it works just fine if I use all of the above approachs.

Adding to what CG said, when I have a weak starter battery and am having trouble getting it to turn over, I will actually move the prop just a bit further, so that it is "hung up" at TDC of the compression stroke. I've found this gives even more of a running start. Make sure when you do this that you either have the glow ignitor off or that you have a firm grip on the prop, as it the engine may fire and whack you in the hand. Also, as others said, make sure you have a good match between spinner and starter insert. The starter you mentioned should have no problem with a full charge on the battery.

There are higher torque starters but they are for 1.0 size engines and up. In fact I start my Saito 1.0 with a regular Hobbico starter (same torque as the Tower Hobbies)
Capo915 suggested :
"One, you need a "running" start for your starter. Meaning start the starter a second before you you apply it to the prop."
A guy at my field has a habit of doing this. Bugs the heck out of me but it is their engine.Jamming the starter onto the engine adds extra wear to the bearings.Not to mention the chance of not hitting the spinner square which can throw your starter, hand and all, through the prop when the engine starts.YES this can happen, it happened to me before I knew better. Luckily the starter stopped the engine before my hand got to the prop.
As CGRetired suggested, move your prop clockwise to just before the compression starts, put your starter on and it will go unless you are hydrolocked.
Make sure your battery has a good charge. That is the most likely problem with not having enough torque.

Thanks for all the replies.
What eventually happens is the backplate of the spinner breaks away from the backplate on the prop shaft, so the prop/spinner assembly is turning while the engine is not. I didn't use to have this problem but once the engine broke in and the compression increased, it began.
Is there a different way to start an airplane engine than using a starter and spinner? I have a chicken stick and it doesn't work-there is so much compression that the prop cuts right through the chicken stick. So anyone know of a way to attach a starter to the prop itself without using a spinner?
Thanks!

Read this thread.
http://www.rcuniverse.com/forum/m_7043935/tm.htm

Highplains,
Does that thread say to try to turn the engine backwards?

Your problem (besides a weak starter battery) is most likely too much prime causing the engine to kick back. As far as starter batteries, gel cells are only good for door stops. A lead acid battery has the best kick, but is awkward, so I use a pair of nicad pack used for RC cars in series.

Can you use a 12V car battery for extra kick?

I use a Tower hobbies hi torque starter and either a car battery or lawn tractor battery.
I can start my OS 1.60 with either. Prime engine, hand flip 3 times to clear any excess fuel.
rotate prop backwards against compression, igniter on and and hit it. after warming up I can back flip it.

I could be wrong (it has happened ) One thing is to "test" the connection of the started and the battery, or try to use the starter on a large 12 volt battery. I believe that those banana connectors on some field boxes are not big enough to get the most juice out of the battery into the starter.

Just my thoughts

Jon

"What eventually happens is the backplate of the spinner breaks away from the backplate on the prop shaft, so the prop/spinner assembly is turning while the engine is not."

1 of 2 problems. Either your prop nut is not tight enough, or your engine is flooded. A stronger starter will only loosen the prop/spinner with more vigor.

If you're using a 4 way prop/glowplug wrench to tighten your prop nut, stop. use a box end wrench and make it TIGHT.

Now, when preparing to start your engine, choke and turn the prop to prime the engine. Watch the fuel lines. Turn only 1 turn after fuel reaches the carb. When using electric starters especially, more prime is bad. If you prime any more than this, you run the risk of hydro-locking the engine, and then your starter will bend the conrod or break the crank. After priming the engine, before attaching glow, always pull it thru a half dozen rotations, to ensure it is not flooded, and that the fuel is distributed thru the engine. If you cannot turn thru compression, STOP. The engine is flooded. Remove the glowplug and turn the engine until fuel stops spitting from the plughole and muffler. Then reinstall the plug and try again, but don't prime any more.

"Is there a different way to start an airplane engine than using a starter and spinner? "

None you wanna try, other than the obvious chicken stick....


"I have a chicken stick and it doesn't work-there is so much compression that the prop cuts right through the chicken stick. "

This indicates a flooded engine. After priming (as above), be sure the engine flips thru compression without the glowplug attached before attempting to start. When you're flip starting, you've got 2 choices. A fast backward spin of the spinner, with your gloved hand, so the engine hits compression (going backwards), ignites, and starts forwards. Described in the post someone linked above, I'd bet. Or, use the chicken stick. Turn the engine ccw (from front) until it begins to hit compression. Place your chicken stick on teh prop's trailing edge, about 1-1.5" out from the hub. Hold plane with left hand, quickly turn engine with chicken stick. If you do this too slowly, the engine may pre-ignite and kick back, cutting your chicken stick. But an engine in the .75 size should be an easy hand start, if it's not flooded.

"So anyone know of a way to attach a starter to the prop itself without using a spinner? "

Nope. That'd likely be dangerous when the engine did start, and now there's something in the way of the prop.....

Good luck,

J

"So anyone know of a way to attach a starter to the prop itself without using a spinner? "

Actually there is.
http://www3.towerhobbies.com/cgi-bin...?&I=LXLW07&P=7
That said, the spinner is not your problem.
You either are flooded or are not tightening the prop nut tight enough or both.

It don't matter how tight you have the nut if the engine is flooded. Read the link!

JB just said it all pretty well. There is another way to fire up and engine without A starter but nothing I would ever tell one of my students about. They have seen me do it but it scares most begginers away.
The one post I saw saying to roll the starter before it is on the spinner sent shudders down my spine and I see it done quite often. If the engine is flooded and you do that you tend to bend or brake the rod, not A good thing.
I have started A 40cc gas engine with my old TH standard starter and used it all the time on my RCS 1.40 gas engine. Works great if your battery is fresh and fully charged, I use it every week on my 1.10, 1.20 and 1.40 glow four strokes. I have now gone over to using one of those take along car battery jumpers and it really gives my engines A good zing.

I'll be in the same boat when I get me new plane ready. I am going to hook two 12 volt batteries in series to get 24. Any reason why this would be a bad idea? Thanks

Ok, its a Super Tigre for petes sake! Thre made to run on FAI fuel so they are pretty high compression. Prime it until its slobery, put on the ignighter, grab the spinner and spin it backward quickly. Works very well and I hardly ever have to use the starter.

Stick 40

I have mine set up with a 12V and a 6V in series to give 18V. I start all of my engines this way with my Hobbico starter. Works great and turns over my 120ax with authority.

18V's is easier on the starter and will not over heat it. Some have run 24V on their starters for 5+ yrs with no ill effects.

i can start my OS .91FX with a turbex 2, just back it up against compression before you turn the starter on to give it a bit of a run-up before it hits the compression

WMB, as long as the starter is rated for 24 volts then no problem unless you have to keep it spinning for A long time then like mentioned it will over heat. Most of the cheap starters are only rated for 12 volts. Mine is only A 12 volt starter so by going over to the car jumper I'm getting A lot more AMPs and A lot more zing out of it.
One of my friends had to go to 24 volts for his new G-45 and bought the bigger starter. If used too much it got hot too. I like the idea of just 18 volts, never gave it any thought but think I will give it A try next time I need more poop.

... ive just read the comments about flipping the prop by hand with the ignition live, its kinda like putting your fingers into a giant blender whilst you plug it in, if the engine fired and the person didnt have a hard enough grip on the prop, whats going to be in the way when it starts turning? (yep, your hand!)

you should be able to feel wether its flooded or not by turning it by hand without the ignition live, plus this si much safer.

watch the fuel line, as soon as you see fuel enter the carb give it 1 or 2 more flicks, back the prop up so that its against compression, turn the glow on and crank it over with the starter (not by letting it run before you stick it on the spinner, as mentioned above you could cause damage)

I think they were reffering to starting the engine with a gloved hand (unless a couple of posts where deleted that I didn't see)
a common practice with very large glow and gas engines. I have never done it myself but most of the members at my club do on their big engines.