Takacat tuning

[MadCat]

Hi all,

I'm wondering if there is a guide somewhere, or if anyone can help me on setting up my takacat.

I've recently acquired a 380lx and matched it up to a 15hp 2 stroke Yamaha. Im new to inflatables and I've been told tuning the set up can be a little challenging, specifically setting the engine height/trim angle correctly ensuring minimal cavitation and ventilation.

I'm waiting to finish the registration process before taking it out for test runs, but in the meantime I'm prepping what I can. I've ordered a permatrim in case that is required, but I haven't approached prop selection yet - I still have the standard prop on the yam 15.

Here's a photo, without engine, set up in the back yard while I was testing inflation, deflation and packing.

[MadCat]

I had my first water tests yesterday. Things went ok.
The outboard had some minor issues I need to sort out.

The 15 hp Yamaha (2 stroke) seems like it lost fuel after running WOT for 2 mins. After that it wouldn't run unless it was on the choke, trying to turn off the choke would cut the engine. After a minute or 2 on the choke it seemed to resolve itself and I was able to run without the choke. It stuttered another couple of times, but a quick squeeze of the priming bulb and she'd run smoothly again.
The outboard seems like the throttle screw needs adjustment. It would cut out idling, but with 1% throttle it was happy.
Hopefully both of these are easy to solve. I suspect the throttle screw will be easier than the fueling issue.

The boat itself was super stable. It could easily handle a bit more power, but I suspect a prop upgrade (cupping) would help. 80% throttle felt the same as 100% in terms of boat speed, but from memory revs did increase a little. If I understand correctly, this is likely the prop slipping/not grabbing enough, which a pitch increase and/or cupping would probably help with.


More tests to come!

[Fenlander]

Sorry you didn't get a hello on your first post, so a welcome from me now.

I've only briefly owned a semi-cat type SIB but know they can be tricky to set up for best performance from any particular outboard. Chipko on here has probably the greatest experience with CAT types so I hope he notices this post.

I have the same Yamaha as you, the second of these I've owned. Is this new to you and the first time you've used it? They are generally a very eager and reliable motor. Your problems do sound fuel related and to me a little greater than the idle mixture being out.

I'd check through the fuel supply from air inlet on the tank cap, the pickup in the tank (these can have filters on the end that block) through all the pipe run also looking at the primer bulb. Check the outboard filter too.

After this I'd be stripping the carb and cleaning plus fitting a new gasket set as in my experience there is usually an intermittent or partial blockage causing the erratic issues you mention.

See posts 55 and 80 in this thread when I overhauled the carb on my previous Yamaha 15 2T...

https://www.rib.net/forum/f36/yamaha...e-81611-2.html

What is the prop pitch you have at the moment? In the UK the Yamaha 15 2T is often filled with a 9.75" pitch which is fine for a normal SIB around 3.5-3.8m but a greater pitch will be possible with a CAT type.

Yamaha supply two prop types for this motor, the standard with more of a fine swept blade and one for more thrust with a broader blade more petal shaped.

Finally do you have a mini tach rev counter? Essential to know what revs you are achieving to make any changes to the prop, and to see the results of a change.

[craigh]

Was it old fuel?

[MadCat]

Thanks guys.

I think I fixed the issue. Pulling the spark plugs showed that the motor really wasn't happy running closer at 50:1, so I diluted it back to 100:1 and that seems to have mostly fixed the issue (at least with extensive bucket testing)

The permatrim is installed, but yet to run an on water test. I'll be borrowing a cupped prop fron a friend and I'll compare that to the Yamaha 10pitch prop that is on there.

I'm keen to jump on the water and load the boat up to see how it performs. Registration should be completed this week too, so no longer running the gauntlet for on water tests. Painting on the registration numbers will be the next challenge but the local whole sale paint shop seemed do know which product would work

[craigh]

Glad you seem to have sorted it. Let us know how the on water testing goes.

[Fenlander]

I genuinely hope you get a result from this however I would say last year we ran our Yamaha 15 2T on about 20lit of 50:1 that had been made up for our other outboard. It ran without issue although to be fair it seems a whisker better at low speed running when I mixed up our normal ratio. We run the Yamaha at 80:1 normally.

Chipko on here has both the same Yamaha as you/us plus a Chinese clone of that model, he runs the clone on 50:1 as that's what they advise and I'm sure he uses the same mix for his Yamaha.

[MadCat]

It's interesting the different oil ratio recommendations. The young aspiring outboard mechanic had recommended 100:1 and the manual says 100:1, but there is a plethora of internet advice saying 50:1 or 80:1 is just fine with an occasional issue similar to mine mentioned.
i went with 50:1 for the first trial as that seemed like a safer option with the downsides more limited. Time will tell if going to 100:1 causes issues I guess.

I'm also keen to see how it runs with the permatrim and I'm wondering if a new cupped prop is on the cards. Time will tell with lots of tuning to come I guess.