side to side rear end. Help

wr250r racetech gold valves front and rear. Its been valved for rocks and roots. clickers set to pretty much mid range comp and rebound as per racetechs recommendation. Lately I have been riding wide open sandy wooped out areas(high speed) no rocks and roots. My problem is when I pick up the speed the whoops send the rear side to side. suspension is really nice until that moment. Been having a blast there but just want to tweek this rear end a bit any suggestions? Im pretty close to getting bucked right off the bike. I also have a feeling she's a little difficult to turn at speed. Could be i'm not used to the sand.

Myself, I'd check to see if I get 3.5" of rear suspension sag when I sit on the bike.
That's 3.5" compared to when the rear suspension is fully unloaded and fully extended.

Also, I'd try a couple of clicks more rebound damping next time out there.

Also also, in sand, it's throttle on.

I agree with throttle on in the sand. Finally got in touch with racetech and they suggested the same thing more (faster) rebound. Also suggested I check the sag. ordered the sagmaster tape measure . Its such a pain in the ass converting standard to metric. Will be hitting the sand sunday and starting with 4 clicks counter clockwise on the rebound in the rear(hope that's accurate)? Then take it from there. Bringing along my Argentinian buddy: The reason I have to go faster by the way. he is riding a yz250. he gets ahead for a few moments then I pass him . At the end of the day he's all beat up and i'm ready for more riding.lets see how it goes. will report back

Get your buddy to watch you hit some whoops, its a lot easier to tell exactly what going on that way.
If your bikes not compressing much and kicking sideways add some rebound.
If the bikes packing (not rebounding fast enough between whoops so the rear is staying too low in the stroke) speed the rebound up.
If the bikes bottoming then kicking add compression.

biglake sounds like a good suggestion, will check back on Monday ,let u guys know how it went. I guess what I think its doing doesn't necessarily correspond with what really could be going on back there, hence the second set of eyes. good stuff

ok fellas just came back from the dunes. $500. dollar trespassing ticket. Ouch. New jersey is hard on the off road community. Turned the rebound all the way fast(counterclockwise in the rear) and it did help. actually I can go a little faster in the whoops before it starts happening(side to side). So it helped but didn't alleviate the problem. I test drove a buddys kps suspension equipped 2007 kx450f and although the power is ridiculously in excess the suspension was spot on. I wish now that I would have had the suspension done by a professional. In conclusion as of today I feel like my whole suspension is operating too slow for the type of riding im doing. When I revalved my bike with racetech valving chart I told the calculation program novice rider ,rocks and roots my weight (190).these numbers worked for that kind of terrain. Before I installed the racetech stuff I would hit a rock and if was not pleasant the deflection I would get and it(Racetech) solved that problem.Now I would like to be able to deal with this without having to spend more money.Where to go next?

Thats the whole point of buying the gold valve kit, it has enough shims in it and enough stack setups you can dial the bike in for any terrian.
Finding out what shim stack you need is the hard part, but since you bought their products race tech will help you out, give them a call and ask for a set up that works better in the dunes.

I went with an aggresive expert offroad setup with my gold valve kit, its kinda of a happy medium set up that can handle a bit of everything, its a touch stiff on roots and rocks but doesnt deflect and can handle small jumps and whoops with ease for when I go to the mx track.

On a side note the WRR has 1 1/2 inches less travell than an mx bike so its never going to work as good in whoops.