Conversion to 50 HP

After studying the parts listing I noticed that Selva Madeira 40 XS is identical to Selva Madeira 50. The only difference is the part number 73 labeled as an exhaust separator. Once again visiting Gommonauti.it forums I was convinced that removing that plate should give more horsepower for my Madeira 40 XS. It seems that the only purpose of that plate is to restrict the flow of exhaust gases.

I proceeded by removing the lower unit as described in the previous post. For my surprise there wasn't any plate, I guess the previous owner has removed the plate already. My engine was manufactured in 2005 and it should come with the plate. I cannot say for sure but it looks like you can remove the plate without disconnecting the shift rod, this makes conversion quite easy. You may need to adjust the mix and idle screws after the conversion. 

Exhaust downwards

Exhaust upwards

So how much more power can you get from this conversion ?

I cannot provide any real data since my motor was already altered, I can only speculate. Selva manual states that on average Selva Madeira 40 consumes 14 l/h WOT and 50 HP model 16 l/h. The provided average consumption for Selva Madeira 40 XS is 15 liters per hour, could this mean that out of stock 40 XS has actually closer to 45 HP and you would get only 5 HP more from this conversion. I also would like to know what does XS mean, is it Extra Strong or something else ?

Anyway, remember that if the motor revs above 5500 rpm after the conversion you need to consider higher pitched propeller, at least Solas Amita 3 (Yamaha) propellers are available in 11-17" pitch range.

Removing the lower unit

In order to check or replace the water impeller one needs to remove the lower unit of the outboard. It was very difficult to find instructions how to do this. I found a message thread on Gommonauti.it which described how to remove the lower unit of Selva Naxos 15. Fortunately Selva uses similar construction on bigger engines also. The method I describe here most probably applies also to Madeira 40 and 50 and maybe also to St. Tropez.

First I removed the propeller and the engine cover and placed a load strap loosely to support lower unit from falling down. I don't think this is necessary but load strap is useful when you are putting lower unit back. Then I drained the gear oil by opening three screws, I'm not sure if this
is needed but I needed to change the gear oil anyway. Then I opened one nut and three bolts and turned gear to reverse. After a couple hits with rubber hammer the lower unit dropped two centimeters. Now a bolt connecting upper and lower shift rod is visible and can be opened, after that the lower unit can be removed.

Update: Removing the lower unit part 2

Selva documents

Some Selva Madeira 40 XS related documents in English:

Owner's Manual

Parts listing

Maintenance specifications

Unfortunately I have not found the service manual anywhere, I have requested that from Selva Marine and regional distributors but no success so far. Maybe some day...

Adjusting idle speed and low speed air/fuel mixture

My Selva Madeira 40 XS is running a little rough and I wanted to adjust idle speed and low speed air/fuel mixture. Unfortunately the user manual does not even mention these topics and I have not been able to acquire the service manual.

With a little help from Italian guys from Gommonauti.it I collected courage to adjust screws next to the carburetors.

One needs to adjust screws 2 and/or 3 to adjust idle speed. Of course your motor needs to be warm before messing with these screws. I adjusted the idle speed to 1000-1200 rpms. You need turn both screws same amount. Update Sep 2018: you need to turn only one screw, it will adjust both carburetors the same amount as they are synchronized.

In order to adjust low speed fuel/air mixture you need to adjust screws 4 and 5.
The range is 2-2 1/2 rounds. I first closed both screws and noticed that they are not perfectly aligned so you need to be careful when rotation those. I used marker pen to color half of the screw, it helps a little when you are turning the screw.
You should first adjust fuel/air mixture and after that bring the idle speed to suitable level using idle speed screws. I don't know what is the proper idle speed range for this motor but about 1000 rpms is the most common value.

Dangar Marine has published a great video about carburetor tuning, I recommend to watch that before touching anything =)

Propeller trouble

I need to find more suitable propeller for my Selva Madeira 40 XS as it's revving 5900 rpm with stock propeller. Stock propeller has 3 blades and size is 11.6" x 13".
I first though that propeller is Evinrude/Johnson compatible but it's not.

For some reason you can install Propulse 6901 propeller without problems.
http://propulse.se/butik/propellrar/propeller-6901/
Don't waste your time with Solas Amita 3 for OMC, it does not fit at least
with stock thrust washer, I was not able to put the split pin, propeller height is the problem.

Selva stock propeller

I was told that my outboard it Yamaha compatible so I bought Solas Amita 11x16" for Yamaha (SOL3311-110-16).

I was able to install this propeller but I needed to remove metal ring on top of thrust washer and place that after propeller.  Then came washer and propeller nut. I used only original parts that came with the outboard.

Blog opened

I have purchased old Selva Madeira 40 XS outboard.
Since it's not the most common outboard out there it's quite hard to find proper information especially if you are not fluent in Italian. The idea of this blog is to share information about maintenance and various technical topics.

Isn't it pretty ? ;)