Convert Suzuki DF4 to DF6

[johnny666]

Hi ...
I have a 2013 Suzuki DF4 and wanted to try to convert it to a DF6.
Read a heap of stuff on different forums, but couldn't come up with anything definitive that someone else had tried and succeeded ....
So, I tried and ............... it worked a treat !!!
First off went through the parts manuals to see what is different, and the answer is "not much"
Other than the external fuel tank attachment, the only parts that I could find that are different are ....

Carburetor (DF6 has a noticeably bigger through diameter)
Intake Manifold (only difference is the mounting section for the throttle cables)
Thermostat (42c instead of 50c)

So I ordered those parts which including shipping came to about US$150.
Installing them was pretty straight forward.
The DF4 is only designed to run to 5000 rpm whereas the DF6 goes to 5750 rpm and that's where the extra (hp) power comes from.
On this version (2013) there is an overspeed protection for both models at 6000 rpm but in later versions the different models have individual overspeed limits with the DF4 being lower (off memory around 5200 rpm). I tried to see what part it is that changes the limit, but couldn't work it out, so if your planning to try this with those later versions, not sure if it will work without solving that.
Anyhow, the result is that the engine revs noticeably higher and my 2.6m inflatable with soft bottom goes WAY FASTER ! Now easily planes 2 up at 3/4 throttle whereas before it would not plane 2 up at all.
You would also want to order a new manifold to cylinder head gasket and carburetor to manifold gasket as both were stuck hard to the old manifold.

Hope this helps someone ... cheers

[tkeithlu]

Congratulations. This is the first time I've heard of success in such a project.

[Compass790]

Originally Posted by johnny666

Hi ...
I have a 2013 Suzuki DF4 and wanted to try to convert it to a DF6.
Read a heap of stuff on different forums, but couldn't come up with anything definitive that someone else had tried and succeeded ....
So, I tried and ............... it worked a treat !!!
First off went through the parts manuals to see what is different, and the answer is "not much"
Other than the external fuel tank attachment, the only parts that I could find that are different are ....

Carburetor (DF6 has a noticeably bigger through diameter)
Intake Manifold (only difference is the mounting section for the throttle cables)
Thermostat (42c instead of 50c)

So I ordered those parts which including shipping came to about US$150.
Installing them was pretty straight forward.
The DF4 is only designed to run to 5000 rpm whereas the DF6 goes to 5750 rpm and that's where the extra (hp) power comes from.
On this version (2013) there is an overspeed protection for both models at 6000 rpm but in later versions the different models have individual overspeed limits with the DF4 being lower (off memory around 5200 rpm). I tried to see what part it is that changes the limit, but couldn't work it out, so if your planning to try this with those later versions, not sure if it will work without solving that.
Anyhow, the result is that the engine revs noticeably higher and my 2.6m inflatable with soft bottom goes WAY FASTER ! Now easily planes 2 up at 3/4 throttle whereas before it would not plane 2 up at all.
You would also want to order a new manifold to cylinder head gasket and carburetor to manifold gasket as both were stuck hard to the old manifold.

Hope this helps someone ... cheers

Well done & thanks for posting. I cant use your mod but it's a good read & something to keep in mind.

[vert]

I have a 2020 model year DF4 that I just upgraded with a carb from a DF6. It works up to about 3/4 throttle but then it seems to bounce off the rev limiter at full throttle. Here is a quick video of the issue: https://photos.app.goo.gl/5wxnoWxDQEmvpA7cA

Is there a way to get this resolved or do I just go back to the old carb?

[fourlyons]

If you can hit the rev limiter aren't you under prop'ed? (Sp?)
That's to say, you need more pitch.

[vert]

Originally Posted by fourlyons

If you can hit the rev limiter aren't you under prop'ed? (Sp?)
That's to say, you need more pitch.

That's what I figured out after some more research... The DF6 has a 7 pitch vs. 6 pitch on my DF4. I purchased the 7 pitch prop and will test it out soon!

[Maurice007]

Hi, where did you order the parts

Kind regards,
Maurice

Originally Posted by johnny666

Hi ...
I have a 2013 Suzuki DF4 and wanted to try to convert it to a DF6.
Read a heap of stuff on different forums, but couldn't come up with anything definitive that someone else had tried and succeeded ....
So, I tried and ............... it worked a treat !!!
First off went through the parts manuals to see what is different, and the answer is "not much"
Other than the external fuel tank attachment, the only parts that I could find that are different are ....

Carburetor (DF6 has a noticeably bigger through diameter)
Intake Manifold (only difference is the mounting section for the throttle cables)
Thermostat (42c instead of 50c)

So I ordered those parts which including shipping came to about US$150.
Installing them was pretty straight forward.
The DF4 is only designed to run to 5000 rpm whereas the DF6 goes to 5750 rpm and that's where the extra (hp) power comes from.
On this version (2013) there is an overspeed protection for both models at 6000 rpm but in later versions the different models have individual overspeed limits with the DF4 being lower (off memory around 5200 rpm). I tried to see what part it is that changes the limit, but couldn't work it out, so if your planning to try this with those later versions, not sure if it will work without solving that.
Anyhow, the result is that the engine revs noticeably higher and my 2.6m inflatable with soft bottom goes WAY FASTER ! Now easily planes 2 up at 3/4 throttle whereas before it would not plane 2 up at all.
You would also want to order a new manifold to cylinder head gasket and carburetor to manifold gasket as both were stuck hard to the old manifold.

Hope this helps someone ... cheers

[Maurice007]

Hi,

Where did you order the parts ?

Kind regard,
Maurice

[SVQuestOfPaget]

I recently converted my 2012 Evinrude (Tohatsu rebrand) from 4hp to 6hp, using a new carb and a new 7.8x8 propeller, both from Amazon. The carburetor was an easy swap, and I did use new gaskets as recommended by the OP. The prop fit perfectly as well. The prop was by "Amarine", and the carb was by "Southmarine" - both generic Chinese parts.

The carburetor as it arrived runs too lean, and has needed some continued tuning to get the engine to run at full throttle without using a little choke. I'm still working on that one. The prop was an easy swap.

With that said, the engine feels much more powerful (with 1/4 choke), and easily gets the 11ft inflatable w/ inflatable keel on a plane with 2 people and gear. The 4hp original carb and prop would just get myself on a plane, and bog down with anything more in the boat.

The only downside I've found is that the boat/engine combo now draws in air and spikes the revs when going down over small waves while on a plane - it feels like the boat gets ahead of the engine. I probably need to adjust the angle on the engine, or install fins maybe?

Unrelated to the original post, but I've never had an easy time starting this engine, and the new carburetor didn't help. Folks with Yamahas at the ramp will give one or two pulls and zip away while I'm still fiddling - and I usually think myself pretty good at starting small engines.

-Eric

[johnny666]

Originally Posted by Maurice007

Hi,

Where did you order the parts ?

Kind regard,
Maurice

Sorry, only just seen your question.
On-line from Megazip in Japan.
I live in Hong Kong, so was easy.

[johnny666]

Originally Posted by vert

I have a 2020 model year DF4 that I just upgraded with a carb from a DF6. It works up to about 3/4 throttle but then it seems to bounce off the rev limiter at full throttle. Here is a quick video of the issue: https://photos.app.goo.gl/5wxnoWxDQEmvpA7cA

Is there a way to get this resolved or do I just go back to the old carb?

Slow reply ... sorry.
As I said at the beginning, the early models have a universal overspeed control system for both engines that cuts in at 6000rpm. Later models have individually tailored systems (D4 5200rpm, D6 6000rpm), so if upgrading a later model D4 you would have rev limiter issues as you have found. You would need to replace the unit that limits the rpm on your D4 with that from a D6, whatever that may be.
Or, fit a higher pitch prop.