1989 Yamaha 25 sf

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Lost Pole
Posts: 59
Joined: 12 May 2014, 14:21
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1989 Yamaha 25 sf

Post by Lost Pole »

Anybody own one? Looking for some help.


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turbotodd
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1989 Yamaha 25 sf

Post by turbotodd »

What's the questions? I'll try to help as best I can.

Lost Pole
Posts: 59
Joined: 12 May 2014, 14:21
6

1989 Yamaha 25 sf

Post by Lost Pole »

Sorry for delayed response.
The price was too good to not take it upon a buddy's word. I was gonna ask opinions , but to go from 6 to 25 for next to nothing financially, with money back guarantee...
I took the risk.
Looks like lots of "rigging" under the hood.
Should be fun.
Will scoot the boat when done.

Why bypass the oil reservoir?



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Lost Pole
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Joined: 12 May 2014, 14:21
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1989 Yamaha 25 sf

Post by Lost Pole »

[ external image ]
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timsmcm
Posts: 112
Joined: 25 Jan 2009, 15:19
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1989 Yamaha 25 sf

Post by timsmcm »

Let's see under the hood. Lots of closeups.

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Buckethead
Posts: 147
Joined: 15 Jul 2012, 22:18
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Location: Union, MO.

1989 Yamaha 25 sf

Post by Buckethead »

Looks like a short shaft motor on a hull designed for a long shaft.

Lost Pole
Posts: 59
Joined: 12 May 2014, 14:21
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1989 Yamaha 25 sf

Post by Lost Pole »

I'll try to snap some pics bf the weekend. Time has been limited with a newborn or I'd be all over it
I appreciate all the looks and willing helping hands.

"Commercial" rated boat but definitely not a a 20"er..... or.... maybe no?

Dunno. Hasn't been a priority


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turbotodd
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1989 Yamaha 25 sf

Post by turbotodd »

Why bypass the reservoir?

2 reasons. Evinrude had oil injection and it was an absolute joke, failure prone pile of steaming feces. Got everyone scared. So now everyone wants to remove it. The Yamaha system is not known to fail but people still remove it all for some ignorant reason. Stressing the "ignorant" part (read again: it is not known to fail). The other reason is sometimes the duck hunters....aka boat racers...will take it off because it adds weight, the lighter the motor supposedly the faster it goes.

The older oil injected Yamaha 25's (like yours) were a sweet running engine. Somewhere in the late 1990's they went back to premix only, and the idle quality would suffer-mostly because owners would mix the fuel at 50:1 instead of 100:1, again, because they were scared that 100:1 wasn't enough oil. But they failed to realize that the oil injected version was basically about 250:1 at idle speed and around 100:1 at full throttle. Anyway, the early injected engines were Very smooth idle for a 2 stroke, VERY smooth, all the way down to 700 RPM low idle speed. They were jetted accordingly. Then people remove the oiler and forget to re-jet the carbs, or at the very least adjust the idle mixture a little. Usually have to richen them up a hair.

When doing a carb cleaning on these, I find it proper to re-adjust the linkages after reinstalling the carbs. Synchronizing the carbs, adjusting the pick up timing as well. Makes for a much nicer running engine than just slapping the carbs back on and forgetting about it.

Lost Pole
Posts: 59
Joined: 12 May 2014, 14:21
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1989 Yamaha 25 sf

Post by Lost Pole »

Thx for that info Tt.
I'd like to restore it to factory after reading that, but priority will be getting it just running for wife and I to make a froggin. It'll be good for us right now. Have a newborn and quality time together is a big commodity.
Been piddling it at about 30 mins once or twice during the week if I get off bf 6.

Got one problems addressed quickly.
Dirt dobbers in fuel line to fuel pump being open ended by previous owner for 7 months.

It fired up once after thirty pulls but started idling down quickly... shut it down after 30 seconds when I didn't see it "pissing".
No "spicket" on exit end, just raw hose. So pulled it and the same....
Was 6" into the hose bf i found it.
[ external image ]

Slowly but surely...


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Buckethead
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Location: Union, MO.

1989 Yamaha 25 sf

Post by Buckethead »

I had worms of some kind worked their way up the pee hole and setup camp. I bought this motor used in March, had no problems. First week of May we went fishing, put in the lake, fired it up and nothing coming from the hole. Installed a new water pump, traced every water line until I got to the last hose that connects to the weep hole fitting. I blew the hose out and all was good. I figured the worms came from the cedar trees close to where my boat is parked in the yard.

nccatfisher
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1989 Yamaha 25 sf

Post by nccatfisher »

LOL looks like dirt dobbers to me.


turbotodd
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1989 Yamaha 25 sf

Post by turbotodd »

watch the main jets. Some of them had 2 different sizes, one goes in the bottom carb and the other in the top. I forget which ones had the staggered jetting but it's worth looking at a parts breakdown.

Replace the bowl gaskets if the gasket is oblonged or they are flat on one or both sides. If not, it's likely to leak a little and because the fuel comes in from the bowl, through the passage in the gasket, then into the needle valve area, if the gasket leaks even just a tiny bit, the float level rises and can overfill the carb(s). The gaskets are cheap enough to just put new ones in.

When you put 'em back on, synchronize them. It's real easy.

Then when you fire it up, check your ignition timing, pickup timing and maximum timing as removing and reinstalling the carbs can change the position of the roller to the throttle cam, which also may change the pick up timing a little bit. Pick up timing should be zero, and timing with the engine at full idle speed should be 7° ATDC +/- 2. Usually 5-7 ATDC is about right if the motor's in good shape.

once it's all set, they purr...I mean they're one of the better idling 2 stroke motors I've ever been around.

tomme boy
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Location: 52732

1989 Yamaha 25 sf

Post by tomme boy »

Is this motor like the 3 cyl one where the carbs had different jets for each of the carbs?

Lost Pole
Posts: 59
Joined: 12 May 2014, 14:21
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1989 Yamaha 25 sf

Post by Lost Pole »

It's a 2 cyl.


Thx Tt. I know what 0 of that means. But I have 2 weeks bf the carb kits get here, so I'll spend some time researching all you've said. Worse case scenario, there's another motor floating around for you.



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