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Suzuki DF140 question...

Old 01-11-2019, 11:44 AM
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bnz
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Default Suzuki DF140 question...

I have a 2005 model and am finding the specs to state that the full throttle rpm range of this motor is 5600-6200 rpm. I have twin DF140s on a Sea Cat 223 and my rpms at full throttle do not come anywhere near this, not even to 5000 rpm. Is this any engine issue? Throttle adjustment?
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Old 01-11-2019, 11:54 AM
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Has it ever had higher rpms at full throttle with the current setup? Could be the propellers not allowing higher rpms.
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Old 01-11-2019, 12:31 PM
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Impossible to say based on the lack of information you have provided.

It could be engines that are for sime reason not running right, it could be simply that they are badly overpropped preventing them from hitting correct rpm range, or the engines could be set far too deep, or a combination of those factors.

But one way or another, you need to address the issue because it is imperative that they can reach at least 6000rpm at full throttle, with something close to your normal load of people and gear on board.
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Old 01-11-2019, 05:33 PM
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Thanks for the replies, going to have to find out more about props it sounds like. Bought the boat with these props and permatrims installed. Always asssumed these were what came fro the factory.
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Old 01-11-2019, 07:05 PM
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If they are like the Suzuki props on my DF 140's (and I am remembering this correctly) the prop pitch should be printed on the back edge of the prop hub. Take the cotter pin out, remove the prop nut, remove the prop washer, and you should be looking at some numbers. Let us know what they are.

EDIT - the numbers are actually on the far side of the hub - just checked one of my spare props in the garage. (DANG it is cold out for NC!!) Pull the prop off and flip it over, then you will see the numbers.

Last edited by Capt. Fred; 01-11-2019 at 07:11 PM.
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Old 01-11-2019, 07:15 PM
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Most of the cats run better with 4 blade props. The Permatrim is certainly not factory. It gives more control of attitude, but may slow the boat slightly.

One issue in cats is if they have foam in the hulls, these become saturated with water--this gives increase of weight--and bad performance. Weight the boat

Definitely you want to be near 6,000 RPM at wide open throttle.

You are not doing the engines any favors if they are luggijng and not reaching full RPM.
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Old 01-11-2019, 07:26 PM
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My cat, with Zuke 140s, came over propped with 3x14x22 wheels. I ran it like that for many years but rarely ever opened her up. When I did, just like yours, only rev'd to 5000 or so. I later put 4 blade 19" props and she turned 6000. Make sure your engines are tuned and running well before you mess with props.
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Old 01-11-2019, 07:30 PM
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Originally Posted by SeaCat22 View Post
My cat, with Zuke 140s, came over propped with 3x14x22 wheels. I ran it like that for many years but rarely ever opened her up. When I did, just like yours, only rev'd to 5000 or so. I later put 4 blade 19" props and she turned 6000. Make sure your engines are tuned and running well before you mess with props.
Yes, make sure engines are serviced, checked and running well first. Then check the engine hieght - its simple - that permatrim should be skimming the surface when the boat is planing at a good cruise speed. If it is buried underwater then its is creating HUGE drag that is slowing everything down. Fix all that before messing with props.
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Old 01-11-2019, 07:38 PM
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Also make sure boat hasn't gotten heavier with either tons of crap on board or waterlogged hull...probably was propped right originally
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Old 01-11-2019, 09:26 PM
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Props say 14 x 22, Suzuki prop. Hull in good shape with no waterlog.

So so how do I adjust engine height if need be? I’ve never really looked at the motors when running to see how low they are sitting. Going to have to do that now.
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Old 01-12-2019, 12:00 AM
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Originally Posted by bnz View Post
Props say 14 x 22, Suzuki prop. Hull in good shape with no waterlog.

So so how do I adjust engine height if need be? I’ve never really looked at the motors when running to see how low they are sitting. Going to have to do that now.
When on trailer and motor trimmed down with permatrim in line with the hull running surface, permatrim should be at same height or up to 1in higher than the bottom of the sponson

If deeper than sponson, you check to see if you can raise the motor, using current bolts and holes on the engine bracket....

Your prop is 22in pitch, that means that for every rotation it moves the boat forward 22in. 140 is a small displacement motor and is also prone to losing power due to engine holder corrosion (search it). Might not be correct prop for you, even though many cats run good with 21.5in pitch, my SeaCat 25 with DF150s included

Also never assume previous owner or factory knew what they were doing. During sea trial always open up throttles and see how high speed and RPMs reach.....before you buy

Last edited by unobtanium; 01-12-2019 at 12:09 AM.
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Old 01-12-2019, 12:41 AM
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My guess is it was over propped from new, and someone put the foil/Permatrim on trying to get it to plane better, always get the setup right before you consider stuff like that.
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Old 01-12-2019, 05:58 AM
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Based on what Seacat22 says, you have props that have too much pitch. Make sure everything else is OK first, though. This will eliminate other possible variables and get it down to finding the best pitch.
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Old 01-12-2019, 06:10 AM
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Forget the lining up with the hull running surface stuff, the best that gives you is a starting point. And you already have that.

The only real way to verify engine height is to get up to a decent cruise speed, trim out to the best running speed, and get someone trustworthy to hold the wheel while you go have a look at wher the anti-vent plate (and thus the permatrims) are in relation to the water surface. As previously said they should be skimming the surface, not submerged in the flow.

If you need to lift a 140 its pretty easy for 2 or 3 people. If you have access to a winch or tackle, use that. If not, use the boat trailer method, if you google you will find it.
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Old 01-12-2019, 06:52 AM
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If your speed at WOT is less than about 45+ mph with the 22” pitch, then you have too much pitch.

Before repropping, get the height of the motors optimized. There is a big swing in RPM as engine height is adjusted. Engine height first; prop adjustment second. The prop should allow the engine to run at 6200 RPM at WOT.
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Old 01-12-2019, 07:00 AM
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Originally Posted by SeaCat22 View Post
My cat, with Zuke 140s, came over propped with 3x14x22 wheels. I ran it like that for many years but rarely ever opened her up. When I did, just like yours, only rev'd to 5000 or so. I later put 4 blade 19" props and she turned 6000. Make sure your engines are tuned and running well before you mess with props.
Okay, just measured my prop space and can't see how a 19" would fit at all. 14" is the largest diameter I can see fitting without hitting the unit above it. Or are you talking 19 pitch?

Thanks for the replies, I'm learning a lot. I can see now where the 22 pitch is definitely too high for my boat. Now I'm off to check the engine height in relation to the bottom of the sponson (can't get it out on the water to check until I finish servicing and new IAC valve installed.
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Old 01-12-2019, 07:09 AM
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He’s talking 19 pitch.
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Old 01-12-2019, 08:07 AM
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I hope its not the case, but very often idle issues are blamed on IAC on 90/115/140 Suzuki, but they are issues stemming from engine holder corrosion.....
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Old 01-12-2019, 08:31 AM
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Originally Posted by unobtanium View Post
I hope its not the case, but very often idle issues are blamed on IAC on 90/115/140 Suzuki, but they are issues stemming from engine holder corrosion.....
The plugs in the engine block have rust but the metal surrounding is solid. My IAC when I pulled it off had a lot of rust and stuff in it. Cleaning it didn't fix the valve opening. IAC makes sense as this particular motor has been rough starting all year. Just can't figure out why my service guy didn't notice it when he did it last year (and why I am learning about servicing it myself this year). Have a new IAC ordered and on the way. Will see how the engine responds once I get the new one in place.

I'm learning when it comes to boat motors it is best to learn and do it yourself if you can. I pulled the anode cover plates off and I had no anodes left. I just wonder how long it's been since they were checked. I had one marine shop service guy tell me the engine anodes rarely need to be checked because they just don't wear! :-o All new anodes for both motors ordered and I'll be checking them yearly from now on.
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Old 01-12-2019, 11:50 AM
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Okay, so here is a pic of my sponson. At what level should the permatrim be above if I was to raise the engine while out of the water? I do have a couple of inches to play with at the motor mount holes.
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