tohatsu 9.9 to 15

boarhawg

Cadet
Joined
Mar 19, 2007
Messages
18
I have a 1996 tohatsu 9.9 and would like to convert it to a 15 or bigger. Can I ? What would it take ? thanks
 

TOHATSU GURU

Admiral
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Jul 22, 2004
Messages
6,164
Re: tohatsu 9.9 to 15

A timing cam that is available from any Nissan or Tohatsu dealer.
 

WillyBWright

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Dec 29, 2003
Messages
8,200
Re: tohatsu 9.9 to 15

AND order 15Hp decals and put them on. ALWAYS accurately represent the horspower. NEVER up horsepower to cheat limits. Both can lead to painful litigation or worse.
 

John_S

Rear Admiral
Joined
Jun 21, 2004
Messages
4,269
Re: tohatsu 9.9 to 15

Assuming he doesn't go on any <10hp lakes without changing back the cam, and is not over powering his boat, what would he be liable for? Like everyone else, he is responsible for how he uses the product after the modification. Is there a law that says the number on the cowling has to always reflect what the current max output of an engine is? Has there ever been a case for someone that was sued and lost for it?

What I can see is, buying 15hp decals, and being caught in freud when the model/serial numbers are checked, on resale.
 

WillyBWright

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Re: tohatsu 9.9 to 15

Operating a boat that is overpowered is illegal in many states. Any accident involving an overpowered boat swings liability to the operator of the overpowered boat no matter whose fault it is. That can include the person or business responsible for installing it or altering it as well. Can I give you a website showing some specific cases? You can Google as well as I can, but I doubt anybody puts stuff like specific incidents on the web. Contact the USCG and I'm sure they have reems of data to satisfy your curiosity. They don't make laws arbitrarily. People dying needlessly is the usual motive.
 

John_S

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Jun 21, 2004
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Re: tohatsu 9.9 to 15

I said "Assuming he doesn't go on any <10hp lakes without changing back the cam, and is not over powering his boat, what would he be liable for?"

ie lets assume he is not doing this to get around some hp restrictions or overpowering his boat. Assume he just wants more hp from his engine and he is responsible enough to make sure he is not violating the above. The question is specificly about labeling the cowling. Is it illegal to not change the label, even though you have changed the engine output? Is it even required to have one? I don't believe it is.

Changing the the labeling on the cowling and then trying to resell will most likely cause a problem when the model/serial number does not indicate 15hp. If it is not illegal, my recommendation would be not to change the label. When he sells it, put the 10hp cam back on.
 

WillyBWright

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Re: tohatsu 9.9 to 15

Or check eBay for a 15 hood. The question might not be so much now, but where does it go after you? Maybe it's sold at auction after an unfortunate event. Some kid's father just bought his son his first motor, thinking that it was a 9.9 and probably wouldn't plane the boat. The kids boat is rated for 10Hp max and there's an accident with a young operator unaccustomed to planing speeds. How do you feel now about proper labeling now? Stuff like this happens. Marina dealers lose customers every year due to disabling accident or death. Mislabeled modified motors get out there that way.
 

John_S

Rear Admiral
Joined
Jun 21, 2004
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4,269
Re: tohatsu 9.9 to 15

Willy,

I don't think we will ever see eye to eye on this. There will never be enough labels in this world to prevent every possible scenerio. As it is, there is so many warnings in any typical manual today, that allot people don't bother from the simple aspect of too much reading.

Now the particular scenerio you described: if it went through an auction house, liability is probably on the buyer. Most are as is, and specificly written to protect the auction house. 2nd, I would have an issue with a father who just hands an unknown motor to his son, without trying it out first. First outboard, is like a first gun, car, etc. It needs supervision and guidance. No amount of labels would solve that either. 3rdly, if a 10hp couldn't plane a boat, a 15 is most likely not over powered, and since most of the gain is in the upper rpms, might still not plane it. If you want slow, and non-planing, buy an electric motor.

Anyway, its time to get off the soapbox. This question has been asked numerous times in this forum. I'd like to hear back on what type of increases were achieved.

Back in '97, I debated over buying a 10hp and converting to 15, vs buying an 18. I went with the 18 (larger displacement).
 

WillyBWright

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Dec 29, 2003
Messages
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Re: tohatsu 9.9 to 15

To falsely represent something is fraud. Period! But I'm glad you're okay with it anyhow.

I wasn't talking about some stupid lawsuit, I was talking about a youngster's injury or death. Lawsuits suck, but let's consider a young lad in pain or a coffin. Heck, it could just have easily been the modifier's own grandson thru inheritance. Information like this tends to die with the modifier, or is quickly lost in the chain of ownership.

I know what your response will be already. "Can you point to one single instance where that has ever happened?" I'm not sure that such specific information is contained in any website. Can you show that nobody has ever suffered injury or death as a result of overpowering a boat? I'm sure we both are plenty aware that it has ... and that's why it's illegal (or should be where it isn't) in the first place.

I'm not blanketly saying don't modify, just do it responsibly or not at all, and Never do it to cheat.
 

bcditoledo

Cadet
Joined
Aug 5, 2003
Messages
21
Re: tohatsu 9.9 to 15

I have a 6hp that I modified to run at 142.46 horsepower with a twin scroll turbo and nitrous. The DNR chased me on a 9.9 lake but I got away. I had a stringer full of smallmouth bass caught out of season. Took them into the woods and cooked them on a fire when there hadn't been rain for months. Set the whole darn place on fire. After that I went and netted perch fry and put them in my aquarium. Then when it got dark I dumped all my used oil in the lake. It made pretty colors at sunrise.
 

tohatsu9.9guy

Seaman Apprentice
Joined
Jul 30, 2009
Messages
44
Re: tohatsu 9.9 to 15

9.9 to 15 won't make enough difference to "overpower" a boat enough to be dangerous, just will give a little more top end. I did the upgrade on my 9.9 and it will run a little faster than a 18 nissan (on a little heavier boat, of course). Nobody is going to notice the upgrade unless you brag about it or someone tears into the motor... Do the upgrade and don't worry about it.
 
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