I didn't check to see if anyone's already said this, but that doesn't apply to slash 2 models. They don't have a butterfly, and the throttle cable pulls the slide, not intake tract vacuum resulting from opening the butterfly as on later models.
Just hold the throttle wide open, and you'll get an accurate compression reading. No need to remove the carbs.
btw, how do you delete an embedded you-tube vid from a quote? Every time I tried, my browser window went blank, and the video soundtrack started running. (sounds pretty sappy, if you don't mind my saying!)
Originally Posted by _cy_
airheads carbs have a sliding piston that blocks air flow when taking a compression reading even with butterfly open. to get an accurate reading one needs to take carbs off or jam piston open.