frenchflys

My first post here! I have a Nexstar that I am getting ready for flight but I have run into a few problems. First the gas tank leaked into the fusealage so I bought and installed a new tank. Now when I start the engine, the plane keeps moving backward. I checked to make sure the prop was on the right way and even installed it the opposite way. It looked wrong and didn't change anything.

The engine I have in it is a brand new O.S. 46 AX. It has given me problems from the start. The main problem is that it shuts down when I try to apply throttle. My needle valve settings are what O.S. directions call for at two full turns. It will run fine and not stall at low throttle. I would have asked the guys at my rc club but it got rained out last night. Thanks for any help guys.

ChuckW

Sounds like the engine is starting backward. This is pretty easy to do if it is overly rich or over-primed. Your best bet is to hook up with the guys at your local club. Once tuned properly, that .46-AX will be a sweet running engine.

big max 1935

My Feedback: (9)

First off wait for it to quit raining ! You may have a "Pusher prop" possible ? The OS needle valve settings are just to get the engine started & need to be adjusted after it is running . Read the engine directions . Go back to the flying field & you will find some help .The engine will need to be run some to break it in .Good luck, MAX H.

aerowoof

I agree that it is probably too rich and running backwards and when you advance the throtle it dies because the timing is not set to run in that direction.try closing the needle valve about a 1/4 turn at a time and see if it runs better

draftman1

too rich,    the manual says 2 turns but that is just a guestamite,  no two engines run the same at that setting, its more of a guideline

andrew66

An electric starter will also cure that problem.  My GMS 47 is tuned real nice, and it always likes to start and run backwards.  Try backflipping (flip the prop backwards) against the compression not through the compression stroke.  It works for me.  I think having high compression makes this happen more.  My webra 40 doesnt even do this when it has a good wet prime.

Another thing that might work, is when its running backwards (secure the airplane) blip the throttle up and quickly down.  On mine this works. The engine kinda stops and then spins the right way.  I personally dont like doing it this way, but it does work.  (takes me a couple tries)

da Rock

Once the engine is running, you're supposed to adjust the needle, not just leave it at the suggested 2 turns.

Did you break in the engine following OSMax's directions? Do that and the instructions in that proceedure will teach you about adjusting the needle.

If the prop is blowing the air to the front of the plane, it'll back up. Turning a prop around doesn't change the direction of the blast, only the efficiency of the blast production.

Ask around at your club field for some help. You'll need flight instruction for sure. Experienced flyers are your best source of info, and you need info.

frenchflys

OK, Confesssion time guys! I'm sure someone here will get a kick out of this. I went to my RC club and told them about my backward engine. One of the guys asked for a look at my 12 volt starter. He proceeded to my field box and went to plugthe correct holes red for positive and black for negative. I toldhim that it would not start that way because at some point in the past I had cut the cord and "THOUGHT"I had sodered the cord inreverse. He asked if he could tryanyways and I said sure! Guess what? The engine roared to life in the right direction ! We both laughed andI shook his hand. I guessif your going to be in this hobby one needs to be able to laughabout silly mistakes.

jester_s1

Yes you do, and that won't be the last one either. Kudos to you for having a cool attitude about being busted in a bonehead move.

red head

You also make a GOOD point as to why we always suggest you check with a local club if possible. ENJOY !!! RED