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Late model Yamaha 15hp 2 stroke tiller

2552 Views 12 Replies 10 Participants Last post by  aflatsnut
Ok, so I got my first gheenoe a few days agao. It came with a mint running merc 6hp, I think its a 90. The gheenoe is a 75 "15.9" according to the title. Only one small patch in the whole thing. The transom was rotten but thats no biggie. I believe its a highsider model? The trailer is a small magic tilt in great shape. It will need new leaf springs by the end of this season, other then that its great! All for $950. Thought the price was more then fair.

That same day I met a guy from Tallahassee to buy his late model yamaha 15hp 2 stroke. He brought it by my house and we checked it over, seemed great. Paid $1000 for it.

Before I go further into the story lets skip ahead to the motor problem. On the test run of the yamaha 15hp 2 stroke, I ran into a funny sound. It seems to only make the noise while doing anything above idle (not while idling) and anything under 3/4 wot and above. It doesn't seem to do it once the motor hits a certain speed which is pretty fast but managable. The sound isn't really loud but you can hear it. Its like
......dunk...........dunk.dunk.................... ......dunk.................dunk...........dunk...dunk....... You can see the motor twitch just a hair when it makes the sound? ANY ideas? Could this be normal?

OK, so back to the story

The next morning I took my family for a little ride in the new gheenoe with the 6hp on it. WOW GUYS! I can not believe that everyone doesn't own at least one of these things! WE ABSOLUTELY LOVE IT! I was skeptical about the stability but man was I wrong. I had no problem standing up wot by myself with the 6 horse. I need a tiller extension asap!

Yesterday morning I woke up early to overhaul the transom and get it ready for the yamaha. Ripped out all the mush and sanded the fiberglass smooth. Took pics of the entire process so I could share and teach anyone that might be nervous about cutting into there boat. Replaced the transom with a 3/4" starboard sandwich, one piece on the outside and one on the inside. Its awesome guys, I cant flex the transom AT ALL if I try.

So I get done about 5pm, new motors on and ready to go. I decide I need to run down to the local creek and test out the yami. Get the boat in the water, it starts first pull. Im on cloud nine boys! Dam thing is so quite you'd almost think its a 4 stroke. So I putter along a few minutes, stop, and GUN IT! Hold on, let me find the smiley that best describes my face. [smiley=1-whoops1.gif] [smiley=1-whoops1.gif] [smiley=1-whoops1.gif] A smiley pooping his pants would be better! HOLY CRAP! I had no idea you guys were insane! THIS BOAT IS SCARY FAST! OK, so I decide, maybe i'll take a little video of the acceleration speed of the boat. Now understand, Im only telling this story to save someone else from making the same mistake. We are all very fragile and a wrong move can be deadly. I decided to try to make a small video to share, while hoping up on plane and entering the fourth dimension, bad idea. First off, holding the camera took a hand of the boat. Second, I had only a couple runs experience with the new motor. Anyway, I was hauling arse and as soon as I came off plane I got the wobbles. My foot slipped, tiller went completely sideways, so did boat, camera went overboard with all the pics, I **** my pants, boat almost slammed into the shore..... Very scary! It taught me a very strong lesson. Don't take these machines lightly, they can kill you. I will say that I think most other boats would have flipped. I dont know how the gheenoe didn't flip, but it didn't!?! WOW!!!! I really can't believe it didnt flip! I had to be going at least 30 when it turned sideways. The buff bashing bonehead, almost died!

Please let me know if you can help with the motor issue.

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Glad you didnt get hurt. Wear your kill lanyard and your PFD. If your afraid you will look like a rookie with the PFD you could always conceal your identity by wearing a buff. ;)
In alll seriousness a kayaker recently died on the Indian River. No PFD.
Glad to hear you (and the boat) are ok and possibly only some hurt pride :( I hope you were wearing a PFD or will possibly consider one for future use at least under power. I will also say you write a very entertaining story. You should have much to contribute for fish reports etc. in the future. Keep em coming.

BTY, sorry can't help you on the motor thing though
Thanks guys. Like an idiot I was wearing neither my kill nor my pfd. I forgot the kill being in such a hurry to test the motor. I brought the pfd along but opted to use it as a foot rest. When boating with family we always are 100% safety first. It wouldn't be a family if dad was floating in a creek. Like I said guys, it was a real smack in the face. I've always been wild, I slowed down quite a bit when I had kids. Now I will be entering my third and final stage of metamorphosis, Worry Wart.
So did the boat flip? did the engine fill up with water?
glad your ok but i have to say iam tearing up craken up at your story thats awsome glad you shared it
Glad you are okay. You should also bolt your motor through the transom otherwise you will be telling a story of a lost motor :(

Is it a metallic sound?

You need to compression test it first to make sure you have even pressure in both cylinders.

Can you tell what part of the motor the sound is coming from?

Run the motor out of the water on ear muffs and see if you can find the sound. Don't rev your motor too high.
So did the boat flip? did the engine fill up with water?
No man, I was almost upside down and somehow it stayed right side up in the end? It was crazy!

I did indeed have the motor bolted through hull.

Thanks for the tips. I'l see if I can rent a compression tester at autozone.
Glad nobody is hurt...

If I remember - doesn't OSWLD have a 40 on his?

Welcome aboard and I have no clue what the noise is other than a fuel starvation issue (maybe dirty carb).

Also sent you a PM
Thanks guys. Im sure a few of you were kinda happy I lost my cool little fuji waterproff camera. Karma? Maybe? Stupidity? Undoubtedly. BOY, if I could have only found it, the footage I would have had!!

I have a few idea's on the motor. I was told that the carb actually has two jets. A slow and a fast to put it in layman's terms. Maybe whats happening is im getting the "skip" as I hang out in the rpm zone that switches from slow to fast? It doesnt seem to happen once I get past a certain point which makes me think its nothing to serious, I hope. Im also gonna swap plugs out. The plugs that are in it seem to be gapped a little more then the 1mm recommendation. Im also going to spray some carb cleaner in as its idling. If non of these work and I feel theres really a problem i'll back the lean screw off a hair. I have a few other cheap ideas if those dont do it. I'll keep you posted. Once I feel 100% proud of her, i'll snap a pic for you guys. Nuttin fancy but she sure is functional!
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LMFAO!  [smiley=1-lmao.gif] [smiley=1-beer-german.gif] [smiley=bravo.gif]That was a funny story. Please try to retrieve the camera if at all possible, the footage has to be epic. Something about the design of the Gheenoe makes it extremely hard to fully tip. I believe it may be because a lot of the boat's mass is below the water line. A buddy and I got drunk a few summers ago and tried to tip mine because the fish weren't biting. Couldn't do it. Anyways, do some research before you spray carb cleaner or starter fluid in your motor. I could very well be wrong, but I remember hearing that it's not recommended with these motors.
Spraying carb cleaner or starting fluid into a two-stroke starves the engine of needed lubrication. When it's burning gas/oil mix, it's lubing the bearings, cylinders, etc. When it's running on something else, not only is there no oil there, what oil residue is there is being washed away by the solvent.

A short shot to get it fired is cool, any more than a couple seconds of fueling the engine with either is very damaging.
Spraying carb cleaner into an outboard is a waste of time. The inside of the carb may be what's wrong and the carb cleaner will only go through the throttle body and into the powerhead. Try new plugs (check gap) first. Also you can borrow a comperssion tester from most autoparts stores. Do this on a cold engine and turn over about 7 revolutions to get reading. All plugs should be out. Look for similar readings each cylinder. A new one will be about 125-130 psi. If you have uneven readings nothing short of a rebuild will fix it, however if you can live with it it could last a good while. Seafoam may also help if the problem is carbon build up from too rich an oil mix.

Thoroughly confused now?

Good luck

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