I'm having problems with my new Nexstar and the OS .46 - my first R/C airplane.
I was able to get it off the ground this weekend at 1/2 throttle and flew/landed it successfully, however it hesitates/sounds like its choking, is very sluggish and will only run at half throttle or below. I've done all the adjusting and tuning possible with no effect. Afterwards, a very thick, orange (slightly darker than the nitro I'm using) goop can out of the muffler. I beginning to think the nitro may be the problem, but the manual calls for between 5-20% nitro so I went with 10%. I'm new to the hobby, so any help you guys can offer is greatly appreciated!

Are you flying at a club? If so somebody there can likely help you tune the engine. Do you have an instructor?

The goop you are seeing is the oil from the fuel. it is normal to have some all over your plane after a flight. It sounds like the engine is rich though (too much fuel/too little air). If you have the .46 FXi with the limiter on the high speed needle, pull the limiter off. Adjust the high speed needle a couple clicks at a time until you get maximum RPM at wide open throttle. Then richen it slightly by turning it 2-3 clicks counter-clockwise until there is a very slight RPM drop. Next comes the low speed needle. This is the small screw in the center of the throttle arm. I would turn it in or out (usually in) 1/4 turn at a time until you get a reliable idle and good throttle transition.

Since you are new to this, I would really advise getting help from someone at your field. Make sure the plane is properly secured when tuning the engine and keep your fingers, clothing, tools, etc. out of the prop. It's easy to let a running plane get loose and hurt somebody if you aren't careful.

Once you have the engine adjusted well and it is broken in you should rarely have to touch the needles again unless there is a pretty big weather change or you switch fuels.

Hate those problems[]

10% nitro should run just fine in the .46 AX. Looks like you have may have carburetor problems! Sounds like you maybe fairly new to the hobby, so it might be a good idea to find an old hand at the field to help out if you belong to a club. Be sure to ask questions while the engine is being tuned.

Does the engine lean out when it is adjusted at full throttle, you want to run just a bit on the rich side. If so the bogging coming up from an idle is generally a sign of the low speed adjustment being too rich. It may take a bit of fussing with the low end to get it right. Sounds like maybe things ae a bit rich right about now. Re-adjust the high end once your confident the low end is set correctly.

Thanks Chuck and Steve,
Unfortunately I do not have a club or instructor near by(Memphis, TN). I've searched high and low on the web but to no avail. My Brother has been helping me get started, however he lives out of state. I knew the oil build up was normal, but this amount seemed excessive. I was hesitant to remove the limiter but will try that next. Incidentally, I crashed the plane on my 2nd flight. I would like to think the engine trouble caused me to crash but this is not the case, a split second loss of concentration and bright afternoon sun doomed the beautiful plane. Damage was no too bad, wings and tail are OK, but the fuselage where the wing attaches (the pieces that looks like the windshield) behind the engine mount took the full impact. I'm going to try to repair the damage rather than buy the ARF kit as I really enjoy that aspect of this new obsession.
Thanks again.

Go to this page on the AMA site: http://www.modelaircraft.org/clubsearch.aspx

At least one club comes up in Memphis, possibly more if you search by your zip code.

Depending on how bad the crash damage is, you can probably repair it. Don't be afraid to add more wood for reinforcement since this area takes some stress. Be sure to re-check the CG after the repair too in case all the extra epoxy and wood throws the balance off a little.

I just started having trouble with my .46 in the nexstar bogging bad during transition after it idles for 3 or 4 seconds. I believe it was directly related to the new "blue thunder" fuel. I came home and screwed up the low speed setting and couldnt get it to run right. But it did transition better. Im jst not gonna fiddle with it until I get back to the field and get the fellas to take a look at it. Oh and on the second day the guys yanked that high speed adj. limiter thing off. The poor transitioning engine screwed me up a few times on botched landing attempts. couldnt get power right away to pull out of it.

The low end adjustment can be a bugger to adjust at times. If the engine is bogging going straight from idle to full power with a lot of exhaust coming from the muffler its a sign that the low end is set too rich. First lean out the engine's high speed needle until the RPM increases tends to die, then open the needle until the RPM returns and richen it just a few clicks. Now go the low speed adjustment and make small adjustments until the engine comes up to power smoothly from idle. If your too lean the the engine will generally want to stall out. Lastly re-adjust the high speed setting. Its a good idea IMO to fly on the rich side as it prevents overheating most engines lean out somewhat once airborne. I like just a slight trail of exhaust when load is put on the engine while in turns and during maneuvers.