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post #1 of 12 Old 08-30-2012 Thread Starter
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Buying Yamaha 6hp 2 stroke two cylinder - anything to watch for?

Like the title says, saw this Yamaha 6hp 2 stroke 2 cyl for sale and thought I'd take a chance, given their good reputation. It starts very easily, runs smoothly, shifts, revs up.

Is there anything I should watch for? (will give it a good service of course). Going to power my Achilles LS4 with it, as 4.5 knots from my Suzuki 2.5 isn't cutting it

The only odd thing is that the choke lever won't pull out. Fortunately it's warm enough here in CA to start up without it.

I can really see the point of twin 2 stroke vs. a single cylinder 4 stroke - this thing started up on half a pull, hardly vibrates at all, and is pretty quiet. The 2.5 usually needs two good pulls, sounds awful, and shakes the boat to bits.

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Last edited by MarkSF; 08-30-2012 at 12:22 AM.
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Re: Buying Yamaha 6hp 2 stroke two cylinder - anything to watch for?

Use the stuck choke as a bargaining point to get the price down, then fix it.

One cool thing about the 6hp Yamaha 2stroke is that it is very easy to turn into an 8hp! Go talk to your local Yamaha dealer about it! (Unfortunately the trick doesn't work on my Yam 4hp!)

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Re: Buying Yamaha 6hp 2 stroke two cylinder - anything to watch for?

I would be tempted, but 6hp is the limit for my dinghy... is 8hp wise? NB, this is an old dinghy, with dubious seams and suspect wooden transom and floorboards.

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Re: Buying Yamaha 6hp 2 stroke two cylinder - anything to watch for?

The twin cylinder will be inherently smoother than the single.
It is more complex though.
You will find the the two cycle will use far more fuel if it is worked hard, however.
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Re: Buying Yamaha 6hp 2 stroke two cylinder - anything to watch for?

I have had many, many 2 stroke outboard and off road motorcycle engines. The outboards are basically bullet proof when properly maintained. They are smoother than the single 4 strokes I have also owned. The 2 strokes burn a little more fuel but the incremental cost difference is small. 2 strokes of equal power are simpler, lighter, and require less maintenance. Suggest you:

1. Follow the manufacturer's specs for oil mixture and type, don' be tempted to run less oil than spec

2. Keep good properly gapped plugs in it, change them often

3. Don't alter the high speed jetting and run the idle mixture as rich as you can without the motor running rough

4. Drain the carb if it is not going to be used for a couple of weeks or so

5. Make sure the colling water flow is good before you buy it.

6. Check all the fuel filters

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Re: Buying Yamaha 6hp 2 stroke two cylinder - anything to watch for?

Verify the lower unit oil is up to snuff... Two strokes do not require that the engine oil be changed, so many people forget about the lower end.

I would simply run the engine in gear for a min., then open the fill hole, poke a Q tip in, and take out a small sample. If you get brown mayo, that's bad. Metal flakes would be bad too. Dark brown/black stinky oil is good.


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Re: Buying Yamaha 6hp 2 stroke two cylinder - anything to watch for?

Thank you for all the good advice. Will check the lower unit oil as a matter of priority, then go through and give it a good service.

Cooling water flow looks very healthy. Had a new impeller a few months ago.

I got into the habit of running the carb dry on my 4 stroke, and so far have avoided any problems with jets blocking. Also got into good habits keeping the fuel fresh, using stabiliser, etc.

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Re: Buying Yamaha 6hp 2 stroke two cylinder - anything to watch for?

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Originally Posted by MarkSF View Post
Thank you for all the good advice. Will check the lower unit oil as a matter of priority, then go through and give it a good service.

Cooling water flow looks very healthy. Had a new impeller a few months ago.

I got into the habit of running the carb dry on my 4 stroke, and so far have avoided any problems with jets blocking. Also got into good habits keeping the fuel fresh, using stabiliser, etc.
I know this is picky, but running the carb "dry" may still leave a small amount of fuel in the bowl which may leave some deposits after drying. If it is not too difficult to do, draining gets out as much as possible. Just a thought. Sounds like a good motor. I don't have a boat in salt water any more and was basically forced to buy a 4 stroke for use in Tahoe. I think it is just a matter of time that carbureted 2 strokes will be banned in all fresh water use in California.

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Re: Buying Yamaha 6hp 2 stroke two cylinder - anything to watch for?

OK, I fixed the choke with WD40. It was just stiff.

I checked the lower unit oil and it looks new. Will keep an eye on it to see if there is any degredation - the PO said he changed it so I am hoping that isn't because it looked bad...

It seems to run well. So we'll see how it powers the dink!

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Re: Buying Yamaha 6hp 2 stroke two cylinder - anything to watch for?

Does anyone know where the fuel filter is on these engines? I can't seem to find one! The fuel line runs straight to the carb. Should I install an inline one?

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