Ski Twin 40

[Rapier]

Tides not good here, unless a dawn wake-up is attempted, so filled the drum and ran the Ski Twin for 40mins to check all Ok. Plan is to take it down to the hard, launch and moor it to the piles while I do some full throttle tests with a tacho. Ski Twin 40 more power than you bargained for.

Vid here of a drum run - rrrr, pffft, budda-budda..very different from my 71 Merc 400 twin...:-

[Rapier]

After the Ski Twin's lack of performance at Cardiff, despite firing it up in the drum beforehand - I took it apart, popping the flywheel and minutely examining then replacing the bottom cylinder's coil. Went through the carb too, but was getting intermittent spark on the bottom cylinder and couldn't work out why..typical read herrings were discarded yesterday, when Mike T pitched up with known good anti-pop switches and his multimeter - mine were fine. Both of us finally pored over his Johnson 40hp hand-drawn wiring diagram and compared the one we had made for mine, when converting to electric on the Evinrude Ski Twin, and both Seloc and Clymer manuals for the wiring on the genny models. It turned out to be one of my typical electrical faults ...an ignition wire in the loom to the anti-pop (which prevents overrun) was earthed at the junction box! Here's part 2 of the vid sounding much nicer...only issue is very hot water coming from the exhaust bypass, which I assume to be the result of running on the flushette (we found 2 at the jumble and left them at £5 for the pair - were missing the springs and cav plate brackets..)As the Ski Twin has no powerhead thermostat, unlike the Big Twin, I assume the SKi Twin is meant to run hotter - at least I hope so? Time to fix the boat leak now...

[haventaclue]

Some engines don't like those muffs and run hot. Put them on my '69 Merc800 and she'll idle forever and not get too hot.Put them on the '81 75HP Yamaha and she gets hot very quick and even when the thermostat opens she doesn't cool down.Run the Yamaha in the tank will run forever and not heat up

[floater]

Well done Nick good to see you found the problem.
My 1972 Norseman 40 has no thermostat or recirculation circuit around the pump and always seems to run cool with no steam from the bypass. I have only run it on the flusher a couple of times and honestly cant remember if it was any different, not a lot of help I know but if it was noticably hotter I would have thought I'd remember it.

I guess the only way you will know for sure is to run it up in the tank, lucky the hosepipe ban is ended.

[Rapier]

Thanks guys..we were out today, on a one man Itchen and Scratchin run up Soton water - the tides and the 6mph wind won over the scattered sunshine. I ran out of fuel in the central channel near the Jolly and the people in the 50ft Motor boat were kind enough to slow to idle as we blew up river broadside while I scrabbled under the deck for the spare cans. The motor just sounds as if it works for BL ca. 1974 though, 20mph tops - any comments welcome...compare the phantom menace video with Miss Daisy catching Muchado and tell me which you prefer. 11 pitch prop too, which should bring rpm up, despite the 260kg load.

[haventaclue]

I'm afraid that the screaming Merc does it for me,

[Rapier]

Seeing that again is my sentiment too; a travesty to have it lying idle in the garage, but it needs rotten wiring sorted out and I want to fit a starter to it.

[haventaclue]

http://www.mareng.co.uk/mercury-starter ... 2sa2d9sqs3 Cheaper than the 'States. http://www.ebay.com/itm/MERCURY-35-50HP ... 0487860826 , http://www.ebay.com/itm/200311741949?it ... em&vxp=mtr .
A harness redoing,I would say use the tinned marine wire.A lot dearer but will last a lot longer.Though,I must admit I have used wire from a scrapped bus to redo some on my boat. I have also bought an old control box with a harness for the sole purpose of using the wire in the harness for instruments etc.Here I'm trying to teach the Granny to suck eggs .But that Merc sounds great

[Tremlett 15]

I'm afraid that the screaming Merc does it for me,

+ 1

[Rapier]

I'm afraid that the screaming Merc does it for me,

+ 1

T15 that's a given...I blame you for a Merc epiphany, when we met at the last blast - I still have my one owner '73 200 from the Broom Gemini.

Haventaclue, my 400 is the 'crankbuster' version (with under flywheel disty) were the insulation's peeled off the cores - you've given me a great idea as the internal wiring is readily available in many 500 scrappers..the starter motor I have is from a '64 30cu twin 350, but will just add my own loom, without the cobrahead..is just to much to go wrong with the internal loom I have (not to mention the squeeze to get it in and the unknown qty of the external looms I've hoarded.