Selva 50HP Madeira 684cc MAGNUM Boat Performance Spark Plugs revisited

I wanted to test again Brisk racing spark plugs (NOR14LGS) now that I have upgraded to larger carburetors and lifted the Selva Madeira outboard to the highest mounting position.

I'm comparing against Champion L78 which is one of the recommended spark plug types by Selva owner's manual.

I'm only interested in the top speed gain and after careful testing there was a 0.4 knots difference favoring Brisk spark plugs. This difference is so small that it might be caused by weather, how high the outboard was trimmed and the differences in GPS accuracy.
I also found that my Selva Madeira was not trolling well, the engine stalled many times maybe due to too low RPMs. I raised the idle RPMs to 1200 but when the gear was on the RPMs dropped sometimes below 800 and Brisk spark plugs were not able to keep the engine running. With Champion spark plugs this did not happen.

To sum it up I'm not planning to use these Brisk racing spark plugs because I want the outboard idle and troll properly. Champion spark plugs are also very inexpensive.

Larger idle jets for Dellorto 38/34 carburetors

Recently I installed larger carburetors to my Madeira 40 outboard to match the ones in 40 XS / 50 HP models. Although the carburetors came from Selva factory the idle jets did not match the to specification. What I got was #65 although Selva documentation says that 40 XS / 50 HP models use #70 idle jets.

My Selva Madeira was not idling very well with #65 idle jets although I have adjusted the idle fuel/air mixture screws.

It's not particularly easy to find Dellorto OVC parts online, I noticed that EUROCARB is one of the few who is selling those. Unfortunately they had only one #70 idle jet available and told that they are not getting more. I ordered the one they had and then the problem was to find another one.

When I got #70 idle jet I noticed that it was exactly the same as #65 idle jet, the only difference was the size of the opening in the tip of the jet. I discovered also that number 70 meant 0.7 mm opening.

I decided to convert the #65 idle jet to #70 by drilling the idle jet using 0.7 mm drill bit.
I was not using a drill, only rotated the drill bit slowly until the opening matched the #70 idle jet.
I was extra careful not to leave any metal parts inside and used compressed air to clean the idle jet.

Once I installed these #70 jets to my Selva Madeira 40 it started to run more smoothly, at least I felt so.

From top to bottom:
#65 idle jet
#70 idle jet
#65 idle jet converted to #70 using 0.7 mm drill bit

Installing Michigan Match propeller

I was looking for an aluminium propeller with more than 17" pitch but those are quite hard to find. The propeller must be Selva Madeira compatible which basically means it must be Yamaha compatible. I found a Michigan Match 10.9" x 17.6" propeller for Nissan/Tohatsu and decided to order one.

This seems to be some older model which is not in the latest catalog, the product number is 142009.

Michigan Match 10.9 x 17.6

I quickly noticed that this propeller is not compatible with Selva Madeira stock thrust washer.
I decided to use the Yamaha thrust washer that comes with Michigan Wheels XHS hub kit 117, the one I modified a little.

There was still a problem with the compatibility, the diameter of the thrust washer was about 44 mm or (1 3/4 inches) leaving a 2 mm gap. I really hope someone could standardize the propeller fittings, it's very hard to install propellers from other brands. Of course Michigan XHS and Solas Rubex hub kits are trying to overcome these problems.

What I did is that I took magnetic tape and folded it two times to make a suitable adapter ribbon that was 1 mm thick. I used a bench vice to make it more solid, it was easy to install and after some lubrication the thrust washer installed quite nicely.

I think you can use any strong tape, maybe brass tape could be the optimum, I just had magnetic tape in stock 😏

Magnetic tape

Magnetic tape folded two times.

Custom adapter ribbon installed.

Yamaha thrust washer modded for Selva Madeira.

Michigan Match propeller 142009
ready to be installed on Selva Madeira.

Jun 7, 2018 update:

I tried to install the propeller but diameter of the outer body is too large and the propeller was touching the gear case and only barely rotating!
I'm planning to remove some coating and try again, will post an update later on.

Jun 30, 20180 update:

I used some sandpaper to make hub diameter smaller, now it's a little less than 80 mm and propeller spins freely when installed on Selva Madeira 40.

I did some tests on the water and propeller behaved quite well, still the top speed was a little slower than with Solas 11 x 17 so I'm keeping this Michigan Match propeller as a spare propeller.

14200

142009

Throttle valve not opening fully

It's a good idea to check that your throttle valve opens fully when throttle is set WOT position.

I noticed that this was not the case with my Madeira 40 and I was not getting the full power!

Fortunately this is easy to fix, you need to remove the airbox first, then put throttle to wide-open position and check that throttle valves are fully open. If the throttle valves are not horizontal you need to loosen the bolts holding the part number 9005740 "Accelerator cam" and slide it downwards.

There should be no gap in neutral or WOT throttle positions, make sure to test both!

If there is a gap where the yellow arrow points then adjust
the accelator cam by loosening two bolts (indicated in red).
I had a gap in the idle position and thus the valves did not open fully.

Now the throttle valve is fully open in WOT position.

Converting Madeira 40 to Madeira 50 (Part 2)

It was time to test Madeira 40 on water with bigger Dellorto 38/34 carburetors.
I did not change the propeller so the test was done using Signature 11 1/4 X 18 semi-cleaver.

This summarizes the gains in top speed best:

I did not notice any increase in the top speed and the motor did not reach higher RPMs.
So bigger carburetors do not necessarily mean more power. The outboard was also stalling at trolling speed, I need to work with the fuel/air mixture screws.

The remaining difference compared to 50 HP model is the cylinder head, I'm planning to replace also that and see what happens.

Selva Madeira reed valve blades

I was considering to upgrade the stock Selva Madeira reed valve blades to carbon fiber ones but didn't have time look for suitable replacement blades. At least Boyesen makes reeds for outboards.

The stock blades are made of fiberglass so I'm not sure if one can see any noticeable difference in the performance after switching to carbon fiber blades. The fiberglass is good material as the engine will not suffer damage in case the blade breaks (same goes for the carbon fiber). In case someone wants to try different blades I have listed the specs below.

Selva Madeira 40/40XS/50 reed valve blades:

•  blades are not attached to each other, every blade has it's own screw.
•  the number of blades is 12 per reed valve so the total is 24 blades per outboard.
•  the length of the blade is ~52.5 mm / 0.55 inches
•  the height of the blade is ~14 mm / 2.07 inches

Selva Madeira reed valve with 12 blades.

The length of the blade is ~52,5 mm.

The width of the blade is ~14 mm.

The width of the blade is ~0.55 inches.

The length of the blade is a little over 2 inches.

Converting Madeira 40 to Madeira 50 (Part 1)

When I did the carburetor cleaning some weeks ago I noticed that my outboard was Madeira 40 although it had Madeira 40 XS decals.

I have been playing with the idea how to convert this outboard to 50 HP and been studying the part listings.

This is what you need to change (I suppose):

• Both carburetors need to be replaced (going from Dellorto 34/30 to 38/34).
• The intake manifolds, those are the parts where reed valves are attached to.
• The engine head is different.
• Luckily there is no exhaust separator plate in Madeira 40 so no need to remove that!

I finally convinced myself that let's do the carburetors and intake manifolds and see what happens. The engine head of 50 HP model most probably gives more compression, I don't know how expensive that is but one can get similar results by shaving the engine head, I may want to try that later.

I was not able to find second hand carburetors so I decided to order new ones from Engine Marine Part. This conversion is not financially very well justified as the new carbs and intake manifolds costed around 800 € plus shipping 😂.

This is the upgrade plan:

1. Remove the air box
2. Remove Dellorto 34/30 carburetors.
3. Remove Madeira 40 intake manifolds.
4. Remove reed valves from Madeira 40 intake manifolds.
5. Remove tubes and plastic connectors from intake manifolds.
6. Attach reed valves to Madeira 50 intake manifolds.
7. Attach plastic connectors and tubes to Madeira 50 intake manifolds.
8. Attach Madeira 50 intake manifolds, connect oil tubes, and two air? tubes.
9. Move fuel connectors and linking arms from old carburetors to new ones.
10. Attach Dellorto 38/34 carburetors.
11. Connect fuel hose.
12. Make sure that carburetors are synced and closed at idle. Adjust idle and mixture.
13. Put the airbox back.
14. Start the engine!

Stock Selva Madeira 40 intake manifolds.

Madeira 40 intake manifolds removed.

Reed valves still attached to Madeira 40 intake manfifolds.

Reed valves and connectors moved from Madeira 40 intake
 manifolds (lower items) to to Madeira 50 intake manifolds (upper items).

Link arms, fuel connectors and all other stuff
moved to Dellorto OVC 38/34 carburetors.

The new intake manifolds attached.

The new carburetors attached, testing WOT throttle position.

The carburetor change operation completed.

First startup after the carburetor change, maybe it's a little bit more angry! 😎

Check also Part 2