I finished my 601 about a year ago. The 650 is nearly the same plane but with a few improvements. My previous flying experience was primarily in single engine Cessnas. My previous aircraft building experience (or even maintenance) was zilch. I'd never set a rivet before i got my kit.
In terms of the aircraft itself it flies great and handles very well. In 30 years of flying different planes this is the only one I can put on a spot on the runway, every time. The view out the canopy is spectacular and so different than flying any high wing - and most low wing aircraft.
I do have to say, though, that it's no RV. They are not really in the same class, IMO, even though some versions can look quite similar to the 650 when sitting on the ramp. If I had the time and money to build and RV I might have done it. I had neither. They are a more complex aircraft and as a result have greater performance. For example, all riveting on RV's is with driven rivets. The pop rivets on Zenith Aircraft save a huge amount of time.
Building the fuse, wings, tail and gear is pretty straight forward and after a little bit of practice you can move through the construction quite quickly. Almost all of the rivet holes are pre-drilled at the factory which saves a lot of time. The construction plans are decent but not quite as clear on some issues as I would have liked.
Building the canopy was the one task I dreaded and it was a PITA. However, the video produced my Homebuilthelp.com was invaluable. As was many of their other videos. And they have a lot of good info. on their web site pertaining to Zenith builds and other homebuilding tips.
The real challenge with the plane can be the electrical and firewall forward. If you choose one of the supported engines this will definitely simplify this challenge. I put and O-235 in mine and struggled with figuring out how to put it together.
Zenith provides some packaged instrumentation systems which will simplify the build (if you can afford them). I couldn't, and finally bought the Aero Electric Connection book and started figuring mine out. After feeling completely over-whelmed at all of the info, I finally had an AH-HA! moment. First draw the battery. Now draw the first wire from the positive side of the battery - where does it go and what do I need to know about it?
Using one of the examples in the book I continued to draw the system one wire at a time, progressing in the order the electricity flowed through the system. This "one wire at a time, in order" was the key to eating this elephant. The wiring diagram is something you can work on when you are held up from other tasks like waiting for parts or better weather.
I have to admit, though, I was thoroughly shocked when the engine actually started on the first flip of the switch!
The O-235 engine is not an ideal engine for the plane. It is heavy. A Rotax, Jabiru, O-233 or possibly a Viking would be better choices. I couldn't afford a Rotax or O-233 and ended up picking my O-235 up for $5K. It pushes the plane along at 115 mph at 2650 rpm (75%) - but again, I don't have the best prop. I have a 3 blade Warp Drive prop but a 2 bladed Sensinich or Whirlwind prop will likely add another 10 to 15 mph.
The one thing I stressed out about, unnecessarily, was the weight. Even though my plane came in quite heavy (814# empty), I can still load it up and be well within the CG range.
The Zenith forums are very active and you can get a lot of info there. The factory is also very good at answering questions.
Also, Zenith really does a good job of keeping prices low, imo. If you need extra materials or parts the prices are cheaper than you can source them elsewhere in most cases. Also they are very good at shipping the same day if you call them early enough.
If you've flown light sport, the 650 will be no challenge to transition to. If you've flown typical Cessna's and Pipers well, I can guarantee the transition will be challenging. It's just completely different. In fact, my first transition training flight scared the living crap out of me and I became very concerned I had made a horrible decision.
A few flight hours later and I fell in love with the way it handled. It's just different. For example, most of us have learned to land with "full stall landings". This is the point where you are at you lowest forward speed and hence the safest point with which to meet the ground.
Try a full stall landing in a 650 and you'll probably end up with bent gear. The problem is the stall speed is so low in a 650 (44 mph) that the resultant vertical decent rate is very high. You really need to approach at a much higher speed and touch down probably 10 mph faster than your stall speed. It's just different and you get use to it pretty quick.
FYI - I love the elevator and aileron trim on these planes! They work so precisely that it makes flying very simple.
I love my Zenith, though I suspect every homebuilder says the same about their plane.
Gary Welch
Cloverdale CA