Very simply, I have more power at full negative stick then I do at full positive stick. It acts like there is some binding when going positive that slows the rotor speed. This isn't noticed in normal mode, other than having a lack of power. When the head is removed, motor rpm is linear in both modes and in both directions. My guess is that the drive gear is somehow binding on the lower bearing, or the bearing is not spinning freely. I am using cf blades on an otherwise stock setup.

Thanks

My CP Pro had a similar issue, but right out of the box.

I dissasembled the heli down to the frame and put it back together, loctiting and lubing the whole setup as appropriate.

The lower bearing on my Pro was NOT spinning freely previous to maintenance, it seemed as though the shaft was almost bent, but only at certain head speeds. I cleaned and lubed the lower bearing and have since not had a problem.

Do you have the Bell-Hiller head? I have discovered it is possible to snap the drive links on with the mixer levers flipped upside down and it will almost look right but it will behave sort of as you are describing.
Also see if your pitch curve is symmetrical. That is, in idle-up you should have -12 at low collective, zero at center stick, and +12 at high collective. Then when you go to normal mode it should be slightly negative at low stick and up to full +12 at high stick. (If you are using the stock transmitter.)
And for sure check the bearings as bzinfinity says, and the shaft endplay (should be zero).

And if you are using EFLite wooden "symmetrical" blades look carefully at the airfoil. I have had two sets that I swear were flatties mounted upside-down, they weren't even remotely symmetrical. Of course this will make the power seem different from neg to pos pitch.

(sorry, now I see you are using the CF blades, good for you, they are more accurate)

no, i believe it's not binding, is just that you have more positive pitch than negative pitch, (remember, he said the rotor speed slow down when full throttle) i believe it's more like you've got total positive pitch range that you've really stall the motor, i've got a futaba 7c and at first i set my pitch range to full mechanically posible, then realized that the motor will stall very badly. and do you have a cp or a pro? with cp ni-hm batt and cf blades will stall the stock brushed motor real bad. try to decrease your pitch by adjusting the pitch links, or the control rods to even out the positive and negative pitch. hope this helps.

I've already thought about the idea of overloading the motor with too much positive pitch.I can assure you that is not the problem. I get much more head speed and thrust at negative pitch than positive, and this is for the entire pitch range, not just at full stick. I think it has to do with friction somewhere, I just don't know where.

Well, I'll ask again: Do you have a Bell-Hiller head, some CPs do and some don't. If your Bell-Hiller links are flipped over the wrong way (easy to do) it will behave as you describe. I just now deliberately flipped mine over and ran it up to see. I had some binding at positive pitch because of the incorrect geometry and the head slows down. When the blades go negative the binding decreases. and the head speeds up, even though the pitch travel is greater on the negative side than the positive with it rigged this way.
Of course if you don't have the Bell-Hiller head this couldn't be the problem, so I would replace the ball bearings just in case one of them might be failing. As the main shaft pulls up from positive pitch the bearing could be binding, and freeing up when the pitch goes negative or you are just moving it by hand on the bench.

No, this one is stock. Haven't bought any upgrades yet. I don't have time to mess with it today. Tomorrow I can look into it a little deeper.

yes, i understand, i'll say it again, if you've got more positive pitch than negative pitch, then obviously you'll have higher headspeed at negative because the motor ain't loaded that much. try using bdavidson's setup thread. i don't have the link, maybe someone will post the link?

No you don't understand. I can adjust the links so that I have much more negative pitch than positive pitch, and it is still slow with positive stick. With the chopper sitting in my hand, I get unequal thrust. Instead of 50-50, it's more like 65-35. I attribute this difference to the reduced rotor speed in positive.

srry, gotcha now. just thought you might overlooked the problem.
so...
unplug both motors, try to see if there is binding, if there is, you've found your problem. if there isn't, then i really dunno, you might want to change the bearings to give it a shot, but i really seriously doubt it's the bearings. do you have a cp or cp pro? if you have a cp, then you might want to switch to lipo, the stock ni-hm along with cf really dont have enough power anyways.

Where's your trim set?

trim setting makes no difference on rotor speed.

I disagree, read this post through, particularly about 2/3 s down the page by turboomni, and you will understand where I was going with this. This is the only way I have found to "modify" your throttle curve with the stock CP TX. http://runryder.com/helicopter/t224578p1/

orlbuzz

Thanks for that link. I'll get on it soon!

There aren't many places for it to bind. With the rotor head off you said the rpms are symmetrical--this is hard to determine on an unloaded motor without a tach but I'll take your word for it.
Do you have any end play at all in your main shaft? There should be none but it should not be soo tight that the bearing is loaded in thrust--in technical terms the end play should be 0 to +0.0005, that is not squeezing tight but no more than half-a thou play. This is of course adjusted by the shaft retaining collar, which by the way must be on the right way up (coned part toward the bearing). And of course your bearings are properly seated in the fuselage mounts.
With the end play set correctly, and with the head off, if you push up with your finger on the bottom of the main gear does it slow down substantially? If so then you need new bearings. They are only like seven dollars for the pair, I'd replace them just on spec.

Okay guys, problem solved. Since this is my first helicopter, I can plead ignorance. I followed the procedure outlined in the above link, and now have a very good collective, with symmetrical power in both positive and negative stick. What I was neglecting was the three arms from the servos. They were out of adjustment giving me much too much positive pitch. I was thinking the only adjustment I had to deal with was the same ones used for tracking the blades. Now I know just enough to be dangerous. Should fly much better with a higher rotor speed. Thanks to all who posted.

So, we nailed it in posts # 3 and #4, didn't we. Oh well, I guess free advice is worth what you pay for it.
At least now you know a bunch of other stuff to check the next time it happens.