Yamma-Fox

Nice!
Hopefully I'll get my plane done and we can get out lake hopping someday!

X2 on all that ppilotmike!
Yeah I tried Airbus...  glad I was junior at the time and got kicked off it. 
Never did get along with their idea of how an airplane is supposed to fly!

Ski doo snowmobiles used their HAC and DPM system on sleds for about 10 years.
I had a bunch of them and even added hac to a sled that didn't have it (just looked up the hac parts on the microfiche).
Float bowl pressure regulation...  worked really well but I did have some failures over the years.  Default fail is rich.. which is good, but the sled would only pump about 40% power when it failed.  Reasonable failure mode in a sled but not so much in a plane!
Man, I dont know... an attempt to re-create a alt compensation unit in a 2 stroke would require tons of testing, fiddling, reworking, and possibly engine rebuilding if you mess it up and overtemp in the R&D process.
Think I'd rather pick up a 600 etec and try to build a psru adapter plate for it! (Direct injection, "FADEC", and 120 HP)

I work with a lot of FAA guys and 99% of them have been true professionals, a pleasure to work with, providing valuable input and insight.
As to the 1%, they are everywhere in life I guess! 
Sounds like the OP found some 1%"ers"  who thought they had a chance to strut their stuff.   Nicely handled by the way, no point in causing a fuss unless they started thinking they were going to hand out a violation...   then I'd take the "yes sir" gloves off and dig into the regs and stand my ground.
I have done that before and the situation quickly dissapated when they saw they were mistaken.

So far I have pretty much sucked, so my lies would revolve around how good I still yet plan to be!  LOL 
I'll mark it on the calendar and see if I can find ya.

Ok guys, finally got to that rx-1 test running with 1 (and 2) of the 4 cylinders down:
Yamaha RX-1 Performance Test on 3 cylinders:
Ok, so part of my decision to go yamaha was that (since it does not have dual ignition) it would perform adequately on 3 cylinders if one were lost to a bad coil, spark plug,  carb blockage, stuck/burned valve, etc.
So I put the theory to test out on the snow today by pulling a coil lead off a cylinder.
Results were better than I expected,  with an easily started motor, good idle, and an estimated 80 hp output.
Details of test:  (All speeds are off the snowmobiles "dreamometer", which are accurate in comparison to one another, but all read high by approx 8%). 
2005 Yamaha RX-1, 30 deg F day (heat wave here in MN!) through 2" of loosely packed snow.  Top speed 78 mph with the #2 cyl coil unplugged.
That compared to a MUCH lighter 2012 Ski Doo 600 ACE (60 hp 4 stroke).  Top speed 64 mph.
For the 100 lb heavier RX1 to go 14 mph faster than the  ski doo in loose snow would probably take between 15 to 25 more HP.  (Note that a lighter 90 hp ski doo I ride occasionally would have gone about 85 mph in those conditions) 
So I am happy in those results.  The engine sounded and ran surprisingly well!  And 80 hp would be plenty to fully operate my kitfox 5 which was designed to use an 80hp rotax 912 as the normal powerplant.
Conclusion IMO is that dual ign is great, and would be preferred.... but it does only cover ignition redundancy.  I prefer the yamaha (with it's extra power reserve) which could carry the day very well with ANY failure of power output from a single cylinder.
 
Running on 2 cylinders test:
Test results running on 2 cyls (#2 and #3 coils unplugged):
I'm really surprised by this one,  started right up, idled fine on the all cyl idle stop, ran 53 MPH down the trail!!
That's gotta be 50 HP!
I was guessing it would have done less, but that would keep me in a gentle drift down in the plane... giving 10 times the options and time for a emergency landing.
Really happy to see it perform like that!

OK.  So a member here whom I highly respect brought up a challenge to a premise I had made when choosing the RX-1 motor for repower.  I am glad he did because it helped me come up with a plan to test my guesstimate.
My premise was that if an RX-1 lost a cylinder for some reason (bad coil, spark plug, burnt valve, flake of gunk plugging a main jet.... whatever) that it would still pump out about 70-80 hp running on the remaining 3 cylinders.  Note here that the RX-1 uses four fully independent "CDI/coils" integrated into each of the spark plug caps, so in a very loose sense it does offer some redundancy in the ignition system. 
Based on my experience with my 65 hp KF2 on lotus floats, I figure that 70-80 HP would be enough to eek out a meager climb (150fpm) in my heavier KF5 on lotus floats.
UPDATE / EDIT:  (Jan 2018)
Ok guys, finally got to that rx-1 test running with 1 (and 2) of the 4 cylinders down:
Yamaha RX-1 Performance Test on 3 cylinders:
So I put the theory to test out on the snow today by pulling a coil lead off a cylinder.
Results were better than I expected,  with an easily started motor, good idle, and an estimated 80 hp output.
Details of test: 2005 Yamaha RX-1, 30 deg F day (heat wave here in MN!) through 2" of loosely packed snow.  Top speed 78 mph with the #2 cyl coil unplugged.
That compared to a MUCH lighter 2012 Ski Doo 600 ACE (60 hp 4 stroke).  Top speed 64 mph.
For the 100 lb heavier RX1 to go 14 mph faster than the  ski doo in loose snow would probably take between 15 to 25 more HP.  (Note that a lighter 90 hp ski doo I ride occasionally would have gone about 80-85 mph in those conditions) 
So I am happy in those results.  The engine sounded and ran surprisingly well!  And 80 hp would be plenty to fully operate my kitfox 5 which was designed to use an 80hp rotax 912 as the normal powerplant.
Conclusion IMO is that dual ign is great.... but it only covers ignition redundancy.  I prefer that the yamaha (with it's extra power reserve) which could carry the day very well with ANY failure of power output from a single cylinder.
 
Running on 2 cylinders test:
Test results running on 2 cyls (#2 and #3 coils unplugged):
I'm really surprised by this one,  started right up, idled fine on the all cyl idle stop, ran 53 MPH down the trail!!
That's gotta be 50 HP!
I was guessing it would have done less, but that would keep me in a gentle drift down in the plane... giving 10 times the options and time for a emergency landing.
Really happy to see it perform like that!

And hey Leni,  you're a sled guy too.
Can you look over my estimations here and give your opinion on their accuracy?  Thanks

Yeah!!
Is that Teal in the background?
Guess he never did show the scale of his new project in the CAD renderings...
WOW!

Like I say... now ALL of Minnesota's 10,000+ airports are open!

Yep, I just added you over on the Yamaha Aircraft Conversions group.   I am an admin over there... I go by "Anatoli".
Glad to have you there Ian!  Teal reccomended you and told me about your areas of expertise.
As far as a modeled engine I know of no one who has done that yet.   Morten Wiik has modeled up an engine mount, but it would be great if someone were to scan the entire engine someday.
Put up a post about that on Facebook and we'll see if we can get a taker!

I am very sure there is at least a provision to ferry a plane in to a facility to get an overdue xpdr cert done.
Guess I would go along those lines.  Mark it inop and to be recertifiied as soon as practical.
 

As far as my research on the scimitar shape, I found that it runs smoother and quieter, cruises very slightly more efficiently, and has better trans-sonic properties if you were to get the tip speed above .89 mach.  Downside is that it has a little less static pull.
So I decided to go a little longer scimitar than I would have gone with a straight blade  (to regain lost thrust) that will turn with higher tip speeds... but it should be able to handle that better.

Need a aerodynamics expert here, but I was thinking about putting some of these on the underside of the fuse... right across slightly fwd of where the lift strut attaches and the fuse makes the bend up to the tail.
Speed mod,  keeping airflow from separating as much around that bend.
Nutty idea?
I'm thinking it might be good for about 0.25 mph. LOL 

Very nice!
Mine is gonna have the measles... or maybe more like the elephant man!

Nothing could go wrong there!!

Dang.
That is one big reason why I am moving from skiplane to full lotus float-skis.
There have been so many good flying days where I didn't go because I wasn't confident that the ice was thick enough...  slush not too deep...   snow not too deep.
I've been through the ice plenty of times on foot, snowmo, atv....  now at least I can eliminate the possibility of adding to my resume' with an airplane! 

Haha!  I was pretty sure I wasn't going to convince you that easily!  
And I am pretty sure that after writing this reply I probably still will not.  But each person reading this will have two sides to this discussion  (which I am sure has been wrestled with before here in a different thread ).  Each can decide for themselves which theory they prefer to agree with.
Ok, so yep in my example I was referring to a two tank system with a finger strainer in each wing tank.
But my main premise is on pure gravity flow, which is spelled out to be tested (at the firewall) on my kitfox.  It needs a certain rate to be demonstrated all the way to empty wing tanks.
And that is my challenge to your idea.  I think that (with a column of air in the header) you would experience airlock during a gravity flow check:
I am guessing that with a full wing tank you might have reasonable flow, but at some point the force of the air trying to rise will overpower the lower head pressure when the wing tank gets lower.  I say at some point your flow rate will be interrupted by air gurgling up the wing fuel line with fuel remaining in your wing.  At that point you are counting on either a fuel pump to create neg pressure in the header (which is not what it is necessarily designed for),  or adequate positive pressure through the fuel cap (which may or may not always be available).
Here's my point:   Does the closed vent header system work?   Absoulutely!  But IMO it does count on a larger number of conditions being met than the vented system.  I say that things (other than the rare "mostly" clogged finger strainer situation) can go wrong easier with a closed system.
I'll and close up here and let you have the last word since I am beginning to repeat my points and we are in jeaporady of a hijack citation, but I will leave anyone else reading this friendly sparring match with the main question that I believe supports my argument:
If the closed system were better, then do later evolutions of fuel systems use it?  I haven't seen all later versions, but it the ones I have seen are vented.

Nice story Leni.
Yeah that totally makes those pretty AK brochures and documentaries seem like the best way to experience AK...
Trying to scare us off or sumthin?

Merry Christmas from Nevis MN!
Nice paint job Bandit!   Heres my old Maule (still fyling down by AXN)
 

Ok Fred, I'll respectfully spar with you here a little!  
I hear your argument against an open vent, and conceed that yes if BOTH finger strainers were plugged up then the open vent system could pull air.
But in that extremely rare case I don't think the closed vent header design would have very much more of a chance pulling through the clog anyway... marginal advantage.
The wing to header is designed to be a gravity fed system, and IMO nothing should impede that..  definitely not a column of air in the header... thats an airlock!   You might be right that a strong pump can pull enough neg pressure in the header to force fuel down past that airlock, but that doesn't sound ideal to me at all.  Without a strong enough pump you are SOL!
They have switched to the vented header on all newwer designs... right??   There probably is good reason for that.

FWIW,  that vent line that you have (with the valve that I assume goes down to a belly drain) goes, in my KF5, back up to top of the wing tank with no valve.
Seems like that is a more moden and possibly better design with a vent that is always open (any fuel slosh through it returning to tank).  With the open vent there can not be air in the header tank at any time (unless wing tank is totally empty).  
Being openly vented back to the tank also helps prevent an air lock in the fuel line:
With your design it seems possible that, if air was in the header tank, that there would be no way for it to get out (with your vent valve closed).  In that case you would have the Airlock:  air in header trying to rise the only way it can go... back UP your fuel feed line!
Without enough positive pressure (fuel cap) to push fuel through the airlock... and not enough suction (elect fuel pump off) it is possible that the airlock could win the battle and stop flow.

So dang many variables involved!
I could tell ya that my old KF2 532 could be off in 75ft and over a 50' obstacle in 150 as best numbers,  but that'd be solo out on a glare ice lake with a 25mph wind at 10F with 3 gall of gas! LOL  
Best numbers, but not realistic numbers at all.  The plane was usually a marginal performer.
My Maule had tiny tires and sat on 3 point with a really flat wing.  Took a long run to get that AOA to grab and pick her up.  Big tires and she'd a been off in half the distance.
Maybe post up which engine, prop, and wheels you are using and guys with similar can add in.
 
 

Yeah,  it must have been a total coincidence in this case...  no matter if the elect pump was on or off.
Not sure if it helps figuring things out on your case,  but my KF 2 would have trouble transferring fuel down from the wing tank to the 6 gall main (behind the firewall) in flight.
I would land and then the flow would start down.  Seems like the fuel cap vent on the firewall tank would overpower the fuel cap vent on the wing tank.  More pressure in the firewall tank (which was basically a huge header tank) seemed like it was keeping the fuel from flowing down during flight.
With that experience, I agree with nlappos and his theory:  wing tank (without cap) under neg pressure which made flow down to the header stop (like my kf2 would).  Elect pump could pull it but the vac pump couldn't.
But in this theory I still have trouble understanding how you would ended up with a header tank full of AIR....  I can see how it may have been under neg pressure, but I can't see where the air would be introduced....  unless it could be pulled back backwards through the vent line by the fuel pump.  But your vent line has a SOV on it.
The air in the header is what I can't explain unless there is an open vent.