I have a PNP pulse xt and the spinner and prop nut everything keep flying off it hasnt done it in air but it has done it 3 times on the ground starting it. Anyone know what can cause this? I use a starter is it spining it off? I have had many other glow planes and all of them evolution engines and start the same way but for some reason this combo always fly off.

Any help would be great didnt know exactly where to post this.
-JR

Is the prop touching the spinner at all ?


Bob

You are not tightening the prop nut down enough...

I use a 9" adjustable wrench... I then tighten the nut while pressing against the prop the other way...

Once the prop starts to bend a bit because of the force I know I ALMOST have it tight enough...

Crank it down HARD!!!

Depending on the thickness of your prop, the nut could be 'bottoming out' against the non-threaded portion of the crankshaft before the prop is tight. A thicker prop washer, or even a second washer, may be needed.

Sometimes the combination of plastic prop and plastic spinner backplate allow slippage. Sandpaper, or screen, washers can sometimes eliminate this problem.

And, use a real wrench (not a 4 way glow plug wrench) to get the prop tight. Snug is not enough, it needs to be tight.

thanks for everyones help, I was always scared to over tighten it didnt know if it would crack. I will check it in the morning see if I can tighten it some more and try it, and yes the prop does touch the spinner, I was tought to make sure it does other wise it would snap it off when it starts

The prop SHOULD NOT touch the spinner.

Neither the cone itself nor the edge of the backplate.

Only the center ring of the spinner backplate should be in contact with the prop...

Look at the picture on page 12, step 4, of the manual. You should have visible clearance around the prop blades when everything is lined up correctly. Do not be afraid to trim the spinner with an exacto or grind on it with a dremel. Keep both slots as close to the same size as possible but do not drive yourself crazy over it.

Usually if the prop and spinner fly off when you put the starter to it is because the engine is flooded and backfires. No matter how much you tighten the prop nut it can still come off. One thing is to make sure the prop is not up against compression when you hit it with the starter. This will allow the piston to build up some momentum before it tries to fire and hopefully will push on through rather than backfiring. I had one OS engine that started easy and ran great but was really bad about throwing the prop off on the first start after it had not been run for awhile.

I had the same problem with a norvel .40.. some red loctite later and learning how to properly use a starter and it doesn't happen anymore!

Of course i didnt have just the nut coming off, but the entire prop shaft from the main body!

Ricken the mixture a tad. Jim

DON"T use Loctite on the prop nut.

On new 2 stroke engines it happens more. The cylinder on 2 strokes non-rings nitro engines are tappered.

Sometimes you'll flood the engine a little bit..cuasing almost a freeze lock.
So when you press the electric starter's cone againts the spinner, it'll loosen the spinner and prop a little bit at a time.
As stew stated...don't have the engine at TDC when using an electric starter.

if you're going to use Loctite...DO NOT USE RED.[X(]
Use Blue.....

A 4-way wrench is plenty for torquing down the prop. Even when I was a kid, with kid muscles, that was all it took.

Two cycle engines just don't throw props when adjust slightly lean, or even a lot lean. Four cycle engine do throw props when operated lean. While it is very easy to tell when a two cycle engine is lean by ear, four cycle engines really need to be set by a tach.

Throwing a prop or having the prop get loose on a two cycle engine is due to the engine back-firing while starting. This is caused by having too much fuel in the engine. It is so common to over-prime and then hit the engine with the starter. The inertia of the prop, starter, and spinner runs into the back-fire of the engine. This results in the prop getting loose or being thrown.

The proper proceedure is to prime the engine (usually by choking the intake and pulling over), then with the engine off of compression, hooking up the glow plug and pulling the engine over by hand through compression. If it is over-primed, you will feel a bump as the piston compresses the fuel/air mixture.

That bump is what causes the prop to come off when the starter is engaged.

Continue to pull the engine through the compression until the bump stops. At this point, most engines have a period of bump on one pull, no bump on the next. If starting with a chicken stick, pull it through the next bump, and flip the engine on the next. 90% of the time, it will start with one flip. If using an electric starter, use that after the bump. Remember, that until it is pulling through with a bump, then no bump, then it is still over-primed.

Once you start using this technique, you will have no more problems with throwing props. You can work on getting a good idle next.

I really wish starting notes were made a sticky. It's comes up all the time, and nobody seems to know how to search. Plus most of what is posted by people here is just wrong.