I'm a private pilot, but havent flown in years.  

I'd like to get back in the saddle again by flying my friend's experimental light sport aircraft (zenith ch750).  He's got many hours in this plane, but the issue is he's not licensed.  He's one of those old timers who always bombed around his farm in ultralights and never had time for the formality and bookwork of it.  Pretty sure he aint legal to carry passengers and probably not technically legal for him to be flying this aircraft at all.  But thats not my question.

It boils down to he's got the experience with no ticket, I got the ticket with no experience.  I know finding a CFI with experience in this specfic plane would be the perfect scenario.  Am I over thinking this?  Should I just say, "screw it", go fly with the guy and get familiar with the aircraft?

Since you you've been away from flying, you need a BFR to legally carry passengers.

If you get that done and then flew with your friend, you'd be the legal PIC and no questions could be raised; I wouldn't risk flying it any other way.

One of these days your friend is gonna get caught up in the FAA's net and the outcome won't be pretty.

This.  Go get current with an instructor.  Then go fly with the guy.  You also need to,make sure the airplane is registered.

He only needs 20 hours & a state Driver's License to get legal as a Light Sport Pilot.  Then he can fly one passenger, VFR day only.

If not for anything to get recurrent on any regulation and procedural changes.  Probably not many, but there's an easy way and a hard way to learn them.

I'd run the fuck away from that thing.

No. Honestly, I think you're under-thinking this.

1. You need a BFR, as previously mentioned; to be PIC with your friend. You need a CFI for that.
2. Is the aircraft in annual and registered?
3. It sounds like you have little or no experience with this aircraft.
4. Do you have a current medical, or know LSA regulations and limitations?

1. You need a BFR as others have said. If you are only going to fly the 750 or another LSA aircraft, you will not need to get a medical.
2. You better make damn sure the 750 is legal. That it is registered, that it is in conditional (annual is for certified, but basically the same idea), and any transponder checks (if installed) have been done, and the ELT has been tested and the batteries are good.  
3. Your friend is not legal to be flying anything but 103, so he sure as hell is not legal to carry PAX.
4. I'd make damn sure I was on the insurance if he has any, and if not..... Not so sure I would fly the plane.

You can get your BFR, get on his insurance (if he has any), and make sure the plane is legal and you can be PIC with his just being another guy sitting in the plane to get the experience to fly that plane. I have a buddy that does not currently have a medical and I fly with him in his Cessna 180 and 140. Another I fly him with his 210.

For insurance be a named pilot, not just 'open pilot' (google 'Subrogation'). And I would not fly it if there is no insurance unless you are willing to cut a check for what he thinks it is worth and have an umbrella policy that covers everything else. You as PIC will be held liable for any damages to people or property on the ground. So if you lose an engine and put it through a fence..... If there is no insurance, he can come after you for the cost of the plane and the guy who owns the fence can come after you for the cost of the fence. If you are "open pilot" the insurance company is there to protect HIM, not you. So the insurance company would pay for the plane and the fence and then maybe try to collect from you.

But I would double check the aircraft legality. You as PIC are responsible and held accountable if the plane's paperwork is not correct. "I don't own it" is not an excuse.  

Thanks for the replies.

I'm going to purchase my own 'non-owned/renters' insurance to fly this aircraft and cover FBO rentals so I feel I got that covered.

My 3rd class medical just expired last month.  I was scheduled to get it renewed just as the medical reform became law.  Then my doc cancelled my apt and closed  shop figuring he just got written out of a job.  3rd class exams was all he did.  I guess until the FAA rewrites the rules to match the law or the 1yr deadline lapses I'm in a state of limbo.  Since my last medical was 5 years ago, I'll get in under the "within 10 years of last medical"  

My plan is starting after the first of the new year, schedule a bunch of time with an instructor in a rental C152 and get current.  Then start flying the friend's plane sometime that summer.

Isn't there another AME in your area?

Ask around the FBO- someone knows.

Yeah, there's like one other guy on the other end of town.  Super inconvenient to get to, but I did see him for my last medical.  Double checked my current medical and it's still valid after all - will expire Jan 31, 2017.  I then remembered I was just trying to get another one in before my 40th birthday.

Still on the fence about spending the time, money and energy to get another medical done.  It's not like I'm flying currently so I might as well wait it out.  Any guesses when the FAA will rewrite/publish the new rules or do you think they'll miss their 1yr deadline?

Since your medical is current, go get a BFR and then you're set to fly your friend's LSA as PIC.

After that, you don't need a medical to fly as Light Sport in a Light Sport-category airplane.

Just make sure the damn thing is registered and in maintenance.