I had a facet 4 psi on my 582.It was plumbed in line before the pulse pump and gave no trouble. Use a genuine facet not a copy I used a knockoff on my 912, this one failed internally after a very short time. It was making the right noises but not pumping.
As above but add a regular huff puff bearing test and regular check of your gearbox oil level as "A" &"B" boxes can have their oil sucked into the engine with little warning if the crank seals are suspect
Black max do a very nice two lever stick mount master cylinder that would eliminate the poor geometry problems of early avid fox toe brakes. I installed a Black max setup on my Drifter and was impressed with the quality of the components .
You may need to upgrade your starter. I my be wrong but check the cam timing as an 80 and a 100 may have different timing. Also an 80 is around 81 hp where a 100 is 97 hp without the air box which won't fit a 4. The gains may be negligible ? I looked in depth at the same issue when my early 80 hp became due for replacement, I can't comment on high DA ,but under 3000ft a 4 is a rocket with an 80!. A zipper kit was on the cards once the warranty had run but looking at how well the 80 goes I am going to leave well enough alone! At the recent national STOL comps I was out performing most of the 180 hp Cubs on takeoff!
I fly with a factory kitfox belly pod that is modified for clearance around the cabane gear. There is no noticeable difference in flight charactoristics with or without it other than an earlier softening of the elevator effectiveness in the flare(vg's cured this). Radiator position is an issue as I moved mine forward to get out of the dead air in front of the pod. The cabane gear is a bit more draggy than the std gear as there was a difference with or without the pod on this setup.
I had never considered running without a vent line but the self venting theory makes a lot of sense. The only real advantage of a vent line is (with a see through line) is to see when the wing tanks are empty and landing should be a priority
Don't use the single ring Pistons! They make it very hard to do a huff puff test and also don't have the side port. Despite the instructions stating the port isn't necessary, it IS needed. The top bearing will start to fail in less than 200 hours. they can supply 2 ring Pistons which are very good quality,but make sure you use the genuine rotax cageless bearing and pin. cheers Dusty
I use a facet 4 psi pump. It is turned on before startup to test its pressure. Start is with it off to check the mechanical pump pressure. Takeoff and landings the electric pump is on. The pressure with both running is 5.2 pound,I also have a bypass on both pumps with a one way valve so if one pump blocks it is bypassed by the other. I currently have a problem with my facet as with the bypass clamped off I have severely restricted fuel flow,these pumps can give problems. My first aftermarket facet lookalike pump failed internally and wouldn't make more than 1 pound pressure .Yes I am paranoid about fuel flow but have witnessed an early 912 pump fail resulting in a forced landing. The 582 pumps appear to be nearly bulletproof with only the pulse line giving problems. So for me the jury is out on this one!