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We are thinking of replacing our Yamaha 9.9s with Suzuki 20s as the Suzuki has fuel injection rather than a carburetor.  We know people who have used the suzuki on their tenders and are very satisfied but were hoping that someone here would have had experience of using them on a cat.

All comments gratefully received.



ps our boat is a one off 38ft ply epoxy cat that is derived from Woods and Wharram designs.

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Yup, we use them both.The 9.9 on a T 30 , the  suzuki 20 on a T30 and the other suzuki 20 on a slightly modified , notably higher bridge deck T30 . Assuming a cruising speed of 5-6 knots neither engine needs to be run flat out but it is nice to know that with 20 vs 10 hp the suzuki will have some more spare grunt if needed . The Yam is pretty old by now but is still as good as ever . problems over the years with the Yam : nothing special actually. Fried a  CDI box , traced that to bad earth, had to replace an ignition coil once , the "sensor" of the ignition failed once. gearbox is a bit clunky and reverse sometimes difficult to engage. As engine controls are located in a rather wet position I rewired the electrics to a switch board  inside the deck cabin. Ignition is now a throw switch, glow and start are push button switches . I also installed an hour meter to remind me of maintenance intervals. as always : it is very wise to have a decent fuel/water separator +filter. The 9.9 is a rather agricultural engine but that is exactly what i like about it . In case of trouble faultfinding and repair is easy . I can strip and clean a carburator. I can not trip and clean a throttle body .

The Suzuki was here ( in Thailand ) not available with extra long shaft . They sell a conversion kit so we had to buy that as well. For the new T30 the leg was even withthe extension kit still short ( cavitated ) so we bought a second leg extension piece and welded a suitable extension on the driveshaft and gearshift activator. The suzuki is despite having nominally twice the HP of the yam very economical with fuel . Also I do like the fact that it can be , unlike the yam , hand/emergency started without having to disassemble half the engine and risking gruesome      hand injury as is the case with the yam. The engine alarms on the yam are simple level/pressure/temp switches which, with the help of a couple of simple relays can be wired to a suitably terrifyingly loud horn . so in case of trouble the user is well aware something is amiss . The suzuki engine monitoring system is steered by the EFI of which I understand but litlle . The buzzer is built in the remote control box and I do not dare to locate it in a more suitable position as I can not fathom what all the wires are for . The buzzer gives a feeble , well, buzz which you are unlikely to hear in stormy weather . The suzuki has safety features which lower the revs in case of overheating or low oil pressure or if it has cavitated more then 100 times . It also gives a certain sequence of beeps when it thinks it's time to change the engine oil. each type of beeps indicates a different kind of fault but what is what is difficult to learn and remember . After each oil change you need to re set the engine monitoring system whihc is a rather clumsy procedure . to reset it after it has cavitated more then 100 times you need the dealer or the suitable software  +cable . The latter of which Suzuki will not sell to non dealers but illegal versions of which can be found on ebay and the like . The Suzuki is notably more quiet then the yam and smoother too . One big consideration is that to service the engine ( oil/filter) or to change the remote control cables you need to remove the plastic panels on the legs . This is not needed withthe yam because the yam has no such panels . removing these panels is fiddly and requires space around the engine . so if your engines live in a well you will be using foul language every time you need to change the oil . Which is every 100 hrs according to suzuki . Have we had drama's withthe Suzuki's ? Yes. On both Suzuki's  the  fuel pressure pump failed after less then 200 hrs . According to Suzuki this is a "weak point". If your fuel pressure pump fails you are immobilized you can not improvise anything. Replacing it is not difficult so if you are wise you carry at least one spare . Sadly they are not exactly cheap . These fuel pressure pumps really dislike water and other fuel contaminants so  you do install a good quality water/fulel separator +filter. The Yam seems much more tolerant in this respect. On balance i prefer the yam because of it's simplicity and ruggedness . This is fairlly acedemical though as carburated engines are fast becoming illegal to be sold new . 

Thanks Jorgen, that is really helpful.  We recently spoke to a Suzuki dealer here and he could not source the long leg, and we had also not realised until then (we had the Yam out and measured it) that the Yam had the ultra long leg option so as that is cavitating now it sounds like the Suzuki would not work for us. 

We are now also looking at a Honda 15 as it has a very long leg option (703) and there is a local dealer (the Yam dealer is in the next town the other side of the estuary, doable but inconvenient) as we can get a high thrust prop for it but what we have not been able to find out is how much of a difference the higher torque of the Yam gear box ration (2.92 v 2.08) against the greater HP of the Honda.  Like you we have been impressed with the reliability of the Yam, it is a shame that the next high thrust model up is a 25hp which is just too heavy for us.


Here are the part nrs for the Suzuki 20 leg extension kit and the prices (in Thai Baht)

SER-01/Extension DF20   2000bath
5710090L50000/Shaft Assy Drive 2280 bath
0932013022000/Bush. 168 bath
5213189L00YAY/Case extension. 2680 bath
0911608151000/Bolt 42 bath
1756199J20000/Tube water. 76 bath
2311189L10000/Rod clutch 102 bath. 
Your Suzuki dealer should be able to order these parts. Suzuki does not sell a long shaft version straight off the shelf , you have to convert the standard leg into a long shaft, for which you need this kit . 
It lengthens the leg by, if I remember well, 4 inch .
If you want more length you buy  1 or even 2  extra " SER-01 extension DF20" , find a good machine/welding shop and either let them machine the correct drive shaft or weld in the the required extra length in the existing shaft.We did the latter.You also need to make a longer clutch rod and water tube but that is easy.
I cant' advise on the power/thrust comparison between the various engines. I have always  found the 9.9 plenty strong enough and the suzuki too. Neither is ever run flat out so both apparently have enough power. which one has theoretically more grunt I find in this respect immaterial 
cheers from sunny Thailand 
                                                                Maxim Jurgens 
                                                                    Siam Sailing, phuket

Gleda (Tiki 38) got 2 20HP Suzuki EFI (DF20A) now. Around 200 hours and no problems yet. Thanks for the hint with the fuel pump Makz. We got the long shaft. It is Ok but draws air in short steep  waves. The props were changed from 3 blade to 4 blade (10 inch, 7 pitch from Solas). They deliver around 6000 rpm at full throttle which is within the range to get the full 20HP. Those are thrust props, but the Yams are real high thrust engines and would be my choice if they had EFI.

We are probably going to go with Tohatsu 15h as they look to be the only one that will fit in the very tight space we have and they have a power tilt as well as a ultra long leg and remote control and we can source them locally.  I would have liked to stay with Yamaha but the next high thrust model was way too big and heavy.  It is rumoured that you can convert a Yamaha 9.9 to 15 by changing the carburetor but I am not a mechanic so decided against risking it.

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