It sounds to me like the methods you've tried have had the servo running at battery voltage and the receiver at BEC voltage. If your receiver can tolerate battery voltage I would remove the red wire from the esc receiver lead and then use a separate port port on the receiver wired to your battery to power the receiver and servo. This way the servo and receiver will be at battery voltage and the battery is a better filter than any glitchbuster capacitor.

Here is the proper wiring sequence to avoid the dreaded glitch on hard acceleration:
FS: High Voltage Servo Harness to 2S Balance Port <Updated 5-JAN-2015> - For Sale: Parts, Miscellany - veteran members only @ URC Forums

https://farm9.staticflickr.com/8797/...b4f1c60e_z.jpg

nitrousdave, your correct in that they would be running at separate voltages. My Rx can handle up to 9.6v.

Bill, it looks like your method gets rave reviews for exactly the problem I'm having. I've got everything I need to wire one up tonight. I'll report back on how it works. Is connecting the red to the balance port somehow different than connecting it to the large battery wire which also caused me problems?

No difference between voltage across balance port vs 2S positive lead other than the harness I made offers a solderless solution... keep in mind that you want both your Tx and Rx turned on before you plug in the battery with a hard wired solution, any raw voltage going directly to the servo without a proper signal can cause it to go full lock and potentially burn up your servo if left on full lock for too long.

Seen way too many HV servos prematurely fail due to improper use.

I'm going to hijack my own thread into a slightly new direction. Since my rx can handle up to 9.6v, I could just power my rx right off of the 2s battery and get my HV servo power that way. If my ESC is 2s lipo compatible, does that necessarily mean that it can handle the higher voltage on the input from the receiver? It's a Novak so I can't really contact them to ask.

If you're going to bypass the BEC, then simply pull the red wire from the ESC into the Rx, then you'll need to use a separate connector to feed power into the Rx through the BATT port hooked up to your 2S pack.

2S = 2 Cell LiPo
2C = 2 x Capacity so if your battery pack is 5000mAh then 2C = 10A charge rate

Thanks again. I did mean 2s not 2c, I edited my post.