Can't comment on the use of the devils measurement system (imperial) as I am all metric -sooooo much easier.
All unwanted comments aside;
Where the component has been supplied by Rotax (fuel pump) stick with their spigot/barb and size all other (up/down stream) fittings accordingly.
Note: It is far better to have a tight hose to barb fitting, than try to seal the hose by tightening the clamp. Clamp for security only.
Spigot /barb fittings - by far the best are the single raised lip/barb type found on most modern cars. The old style multi barbs are the worst.
More unasked for comments;
Avoid standard serrated worm drive hose clamps wherever possible - For fuel & oil hose, use clamps with 360 degree clamping pressure & smooth edges eg Fuel Injection clamps by suppliers like Gates, Proflow. For coolant system hoses use spring clamps.
You seem to have a lot of unsupported hose & wires - talk to a Rotax mechanic or experienced user, about reducing hose movement wear/ damage.
No sign of a fuel return system that will markedly reduce the chances of fuel vaporisation occurring.
You did not describe your cold starting technique - Full Choke (enrichment circuit) and No Throttle. If engine fitted with Easy Start, will go to about 2200-2500 rpm on start up. As engine warms (rpm increases) progressively reduce Choke and increase throttle to maintain 2200-2500 rpm
What fuel are you using ?
Nice aeroplane 😈
