Fun to assemble but found the carburetor very touchy and inconsistent. My son built a beautiful cherry wood box and mount, so it looks great!

I can't believe the quality and what you get for the price. This little guy has kept my attention for a few weeks now. I'm out in the garage several times a day just to run it for a bit.
Speed is adjustable by replacing the governor springs with lighter ones. Using Coleman fuel and Marvel mystery oil for fuel and that seems to be working great.
I've already had it apart several times for cleaning and adjustments, very easy model to work on. Set the exhaust valve, then set the spark timing and away it goes.
Model did come fully setup out of the box, just needed a base and batteries. 4-AA batteries seem to be perfect.
Video is with a different spring configuration for the governor, you can definitely be creative with it.

Earlier I stated my engine was not working and i was going to replace the spark plug and ignition box, im happy to share that this worked. as long as the cylinder has a good oiled seal when you fire it for the first time. 4 stars because I had to put extra money into a model that really should have been in working condition to begin with. Runs pretty good, but i may want to mess with the part that the governor grabs onto (has a ball bearing on the end that rolls on the crank shaft) this part has a lot of side to side play, lowering the play room will help the engine spin at a more "consistent" rate (should be easy to fix if your model may require it), by that I mean it wont slow down as much during miss fires, this also makes it run a little bit faster. removing one governor spring is recommended by many people for slower prototypical operation (vary easy mod). One last fun thing you can do is tap a thread into a already existing hole on the crankshaft end ( do it on the side without the governor), this will let you mount a pully wheel or gear, now you can use your imagination on what you want it to power! Keep in mind its just a mini model, wont power your bike! Hope my reviews come in handy for the next guy to have trouble, or to anyone who wants to improve it.

Well built, everything spins free, has spark, but it took me 5 batteries to get any spark while others only needed 2. Everything checks out otherwise. I tried 4 types of fuel but this engine will not fire for anything, I can tell there is a vary small ignition of fuel when I turn the flywheel and hold it, can hardly feel a vary light thud, vary unusual. I ordered a ignition box to see what happens, Ill also inspect the inside of the cylinder to see if fuel is properly flowing in. (note that the " carburetor" is press fit, do not unscrew it like a bolt even though it looks like it unscrews)

No fault of the seller, I seen in other comments that they got fast shipping, where the item only took a week or so to arrive in Michigan, i also live in Michigan, but it takes almost a month for my order to arrive both times, just luck of the draw I suppose.
You can count on enginediy to get back to you and do what they are able to help you out, but unfortunately they could not help me on this one. for me, its to much hassle to wait two months to ship this back and wait for the replacement to come, not even shore you can return this honestly (same reasons as RC cars). I figure I'm better off trying to fix it myself, one way or another I believe it can be done.
If I'm able, I will submit a update on what I have done to get it running, but I have a good feeling it may be a weak spark from the ignition box or spark plug.

UPDATE
I'm happy to share that this worked. as long as the cylinder has a good oiled seal when you fire it for the first time. 4 stars because I had to put extra money into a model that really should have been in working condition to begin with. Runs pretty good in the end anyhow, hard to fire at first, but it gets easier as the engine breaks in.

TIPS for when you get your engine.

May want to mess with the part that the governor grabs onto (has a ball bearing on the end, used to move the push rod for the air intake timing) this part has a lot of side to side play, not shore if they are all like this, but if they are, lowering the play room will help the engine spin at a more "consistent" rate, by that I mean it wont slow down as much before the next fire happens, this also makes it run a little bit faster, this should be easy to fix by adding material on its brass guide, located on the engine and behind the flywheel.

Next, removing one governor spring is recommended by many people for slower prototypical operation (vary easy mod), while doing the above change may make it go a bit quicker, it still wont nearly be as fast as it would be with two springs. Use two springs if you require that extra power and RPM.

One last thing you can do is tap a thread into a already existing hole on the crankshaft end ( do it on the side without the governor), this will let you mount a pully wheel or gear with a screw or bolt, now you can use your imagination on what you want it to power! Just keep in mind its a mini model, it wont power your bike, but I seen them run a RC tractor on youtube. Hope my review comes in handy for the next guy to have trouble, or to anyone who wants to improve it.

Just got mine, what a great bit of machining. Can't imagine how they can sell it so cheap. Fit and finish is very high quality.a lot of beautiful machining. If you want to have a work of art, and a fun little engine, get it. Note that for this version, you will need to fabricate a base, but just an excuse to get yourself a mill, lathe, .... :)
The shipping was also great, online tracking available for every step.