First flight Valco U12 with Johnson 20

[DIZZYSPOTS]

Well...it was a fabulous 80 degree day here in sunny southern AZ...what better time to grab my wife, a grandson and go test fly the U12
Originally equipped with an older Merc 9.8...the performance was less than stellar. Picked up a very clean 87 Johnson 20hp...complete with CMP composite 4 blade prop...to Patagonia Lake we go.
GPS is on ...make 1st pass: me driving, grandson on center seat, my wife on the bow seat....1st pass into the wind 17mph
Have lunch on the island.....2nd pass with the wind at our back...19 MPH
no more passes....the new fuel line (OEM OMC) and OEM "squeeze" clamps are leaking.....each time we get up on plane....(a first for us...ole 9.8 wouldnt do it.)
but now , each time we get on plane, the motor falls off..then runs crappy ....on the way back to the docks...coughed and sputtered a couple of times.

gonna check a few things out...then check again...thinking air in lines?...plugs?...fuel screen?

also noticed black oil seepage on lower unit: some from a "weep" hole and some more from ? behind the prop

Anyway...the Johnson 20 really woke the little tinnie up....now....maybe johny25's 30 horse mod......

 

[Johny25]

Hey Dizzy First off I am jealous of your weather. The black stuff coming out of the weep hole is no big deal, it is unburnt fuel from your exhaust and it drains out the weep hole when the motor sits after running. And you have a through prop exhaust so black stuff coming out the prop is normal as long as it is black unburnt fuel (smell it) and is not excessive. You will be able to tell the difference between gearcase oil and unburnt fuel.

What diameter and pitch prop are you running?

Fix the leaky fuel line for sure. Did the motor sit for any length of time, if so carb clean/rebuild is in order. What plugs are you running? Fuel is mixed 50:1 correct? Check for good blue spark. Start with the easy stuff first. Does it hesitate at all on take off or midrange or just at WOT?

I am thinking with that little 12' you should be low to mid 20's on the mph.

 

[lckstckn2smknbrls]

Put some Sea foam in the fuel.

 

[DIZZYSPOTS]

Thanks for the replies...
fuel clamps fixed...screw type not plastic
seafoam is now in the tank and fresh fuel...other fuel 3-4 mos old minimum
prop is a cmp composite ...size 10.5 x 11 4 blade
fuel is 50:1 NOT the 100:1 on the label
will check plugs
unk sit time...
as we reached top speed on 2nd pass...WOT..falls on its face...suspect the fuel line air leak
will do all the above before next trip

FYI boat was close to full gross with pax, fuel tank

 

[Johny25]

Well when you get her running good we can figure out a good prop for ya. And if you are doing the HP mod (as I believe you are) then you will have to look at getting a higher pitch prop for your boat. A 30hp motor on a little 12' boat will probably push a 10x15 prop and be scary fast Oh I thought I would mention that I believe you will be over your rated HP for that boat with a 30hp by a lot. My guess is it is rated for a 15hp tops. Not that I haven't run with a few extra ponies more than my boat says it can take, I just wanted to mention it so you are aware of it if not already

 

[DIZZYSPOTS]

Boat data tag from Valco says 20hp...thought that was more based on weight of the outboard not horsepower....20 mph with my wife and grandson felt pretty fast...on smooth but breezy lake... but most of my use is on Gonzaga Bay...Baja...on the Sea of Cortez...beautiful sheltered bay... sometimes like glass... sometimes choppy and sometimes 2 footers!! but try to stay fairly close to shore...(???maybe because the old 9.8 Merc (felt like a 4.9)took soooo long to get out to the outside of Willard...