George,
Thanks for the question. You need to explain what you are attempting to do a bit better. It is not clear.

“live looping”??? What is that? I think I know what you mean but... are you trying to defy the Laws of Physics?

...I can't figure out how to set different tracks to different measure lengths (say I want the piano loop to be longer than the drum loop) and I'm unable to mix while recording.

In Pattern mode, both Time Signature, and Tempo are shared by all Tracks in a Section. While each Section could be set to a different a Time Signature, all Sections respect the current Tempo.
The Phrase Length (that is, each separate a Pattern mode recording) must be set prior to each recording. If you want the Length of one instrument Track to be different from another, you must Stop and set that Length, then re-enter Record.

All Tracks in a Section must share the same Time Signature and Tempo. But before you record the piano Track, set the Length to the number of measures you desire. Before you record your drum Track, set the Length to the number of measures you desire. Each MIDI Track can be a different Length, and will loop accordingly. You could record a one measure drum groove that played over and over, next to a bass line that plays an eight measure phrase. And a Synth Lead that repeats only after 32 measures. But the Length must be set prior to recording each of the Pattern Phrases. Yes, STOP is involved.

The technology must have the Length information before you begin recording so that it ‘knows’ when to loop back to the top.

I'm unable to mix while recording. This is annoying because if I'm playing a song live I have to stop record mode and enter play mode to change the volume of my different loops,

That’s right! Annoying as it may be, changing the Volume while recording would be documented. I cannot imagine that this is really what you want to do. When looping “Mixing” is done during playback, not record. And for a very good reason...

Changing the volume of a Track while loop recording is NOT what you want (I know you *think* it is but it is not). If you are in Loop record and you fade something to 0. It will remain at 0 until it cycles back around and runs into the first command you sent to change the volume. Say you have set the Length to 12 measures... and at measure 9 you begin changing the Volume ... fading it to 0 by measure 12.

The next time it cycles around, measures 1 through 8 would remain at Volume = 0. There is no Volume message to tell them any different.
Then when it runs into your first Volume change command in measure 9 (exactly where you started your fade) it would jump up in Volume and clumsily begin the fade to 0, by measure 12. And you’d never hear measures 1-8.

Automation (the term used for this type of control change data) should be applied only during playback when working in a Pattern loop. Anything you change during Record gets recorded! It is as simple as that.

And because the last command given to a MIDI device *persists* — means it stays as last commanded — If you tell a Part to pan Left, it will remain Left until it receives a message to do something different. If you fade a Part to 0 it will remain silent until it reaches a message that tells it to change. It’s like Newton’s Law of Physics ‘an object in motion will stay in motion until something acts to stop its motion’... motion will persist until a force works to stop it.

Say you are recording a 16 measure Phrase and you press the MUTE button at measure 13... think about it. The Track loops back to the top, it will remained Muted, because there is no message to unMute it. Midi messages *persist*... it will remain muted until you unMute it. Now, say you unMute it, it will remain unMuted until it reaches measure 13 where it will trip over your first Mute command, again. Pretty soon you will not be able to keep the track playing because you’ve recorded all your Mute and unMute commands. Automation mixing is best done during playback. Anything you do during record... gets recorded! It’s as simple and complex as that.

Recording automation is fine on a linear structure, but it is ludicrous when Looping. When looping you have to know when to STOP recording. If you set the Phrase Length to four measures, you know to stop hitting the snare on 2 and 4 after the first four measures... it ridiculous to keep hitting hitting it where it all ready exists. You have to know when to STOP recording.

“Mix while recording” Not while looping!!!— Annoying as it it is, this is how it works. Like gravity is annoying because it keeps on the ground, get used to it. This how it works.

If you are performing live — which is probably what your “live looping” phrase must mean, I’m guessing... you are going to have certain limitations.

Ways around the Limitations
Yes, hitting STOP to switch from record to playback will be apart of your workflow. If you want total freedom you would need to solve your issue exactly like a live ‘DJ’ solves the same problem. Get a second Motif ES! And use a mixer so you can switch between the unit carrying the beat live to the audience, while you prepare the other one, offline.

Now we know that is not practical for most musicians to have two synths... but think about getting a second device (like a small drum machine) that can keep the percussion groove going while you change stuff on your ES. A DJ has to change program on one platter but they keep the groove going with a second platter. They monitor the platter that is offline in headphones, make adjustments, ensure it is back in the same tempo, then make it “live” by adjusting the volume on their mixer so everyone can hear.

It’s like a magician’s misdirection. You have to *invent* your own method of misdirection.This requires a second audio device that you work in addition to the ES.

The ES is certainly a powerful tool but it cannot defy gravity. Neither can a DJ use a single platter and play non-stop in a live situation. Both situations must follow some rules that are like the Laws of Physics. You can defy the Laws of Physics like magician’s do... misdirection.

Hope that helps. Back in the day, I’m talking 17 years ago when the Motif ES was new, I’d use the Yamaha RS7000 or RM1X or SU700 as my “misdirection”... These were grooveboxes that were outstanding for “live” performing!!!

Hello thank you so much for your response, I'll try to explain a bit more what I'm trying to do. My main piece of equipment that I use while performing is a boss RC300. It's a loop pedal that has 3 seperate tracks, each being programmable to be individual lengths and volume. I use this to record loops for the verse and chorus with things like an acoustic or electric guitar. What I use the ES8 for right now is mainly a drum machine. I have a 4 instrument drum pad that I have hooked up to my ES8 via midi. So I use the ES for drums, effects and maybe a piano or organ line. The trouble I've run into is stopping and starting the pattern on the ES8 sounds weird when all of your drums stop for a couple beats and then come back. The way that I have used "misdirection" is through sending the audio out of the ES8 into one of the tracks on the loop station, but as I get better I doubt I'll want to have that 3rd track occupied even for a couple measures if I can help it.

I don't know a whole lot about the groove boxes could you let me know how exactly they all work? I have a general sense of what they're meant to do, but I'd love to know a little more about how they would interact with my keyboard?

I also have a somewhat unrelated question about integrated sampling. Whenever I press it it gives me the notification that DIMM memory is not installed. I have a USB drive plugged into the back but I assume I still have to get some RAM and hook it up to my computer? What I'm trying to do is set up different voices with a few keys designated as drum beats. I'd like to set these up so the drums are set up on 4 keys I wouldn't be playing during the song and set my drum pad to trigger those particular notes that way I could set down a drum line but also riff on the piano if I want to. How would I best go about doing that? For further clarification, lets say I want to take the full grand voice and replace the bottom 4 notes with assorted drums from the Jazz Kit voice and set it as FG1 and set it up on the PLG1 section of voice. And if I do need to plug in some RAM to the PLG 1 slot is there a limit to the amount that I can attatch? I have an old computer and it has a stick of either 2 or 4gb ram, would that be too large? Thank you again so much for your answers they are really helpful and quite well written.