The factory upgrade was to add a "pin" in front of the injector
on each cylinder to help further disperse the atomized fuel for a more complete burn.
It was a waranty fix in 2000/2001, but the motors are no longer supported.
You can tell if you have pinned heads by looking at the spark socket, if you see a hex style fitting adjacent to each spark hole it has a pinned head.
Contact BRP with your engine #'s, they can tell you if a head upgrade was SHIPPED for install. My motors each had an interior tag saying they had indeed been upgraded, verified visually by looking down at the spark socket.
The whole Ficht issue was with excess carbon buildup, had nothing to do with oil senders.
There are tons of different opinions on this, but if oil senders were faulty a modified sender would have been the warranty fix, not a pinned head. They were in fact rushed to market.
Most early Ficht buyers ran standard TCW3 and had problems.
Fichts and ETECs use essentially the same injection technology, thats why ETECs REQUIRE xd100 full synthetic oil . . . and expensive.
Can't run xd100 in a ficht w/o reprogramming the ECU.
Run xd50 along with trustworthy gas, use carbon guard or seafoam, and DECARB every 100 hrs.
Indexing plugs is also great idea for any high performance injected engine but a PITA, I was told not to use spacers by my ficht guru.
They also modified the recommended spark plug in 2001 to a different Champion plug.
Get the factory techs service manual, not one of the consumer grade booklets that ends each paragraph with "see dealer".
Cost about $65.
Do your due diligence and research the particular motor you are looking at, do a compression test to verify each cylinders health (they should read w/in 10% of each other) and don't skimp on the maintenance items down the road.
Good Luck, my FICHTS have served me well for over 300hrs, I don't troll with them beacuse of the carbon issue but have a yami 9.9 kicker for that,
fuel economy is ok, 2.8 mpg at cruise, I can outrun the 2 other Islanders w/yamaha 150's on Lake St Clair no problem, Fichts like it when you put the spurs to em.
Good Luck
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