115 hp tuning

[100333624]

Hello I just finished setting up my boat (engine height, propping etc..) and doing tons of test runs, she runs great! I was digging into some research and realized Yamaha made a 115 and 130 out of the same block? My research indicates its the same motor more or less, that the 115 is a de-tuned 130, that the 130 revs 6000 rpm whereas the 115 revs 5500 rpm. I have a 1995 115, its a 2 stroke V4 with the precision blend injection. I have no complaints with the engine, it runs great and pushes my deep V center console about 49 mph, but I did want to know if there is any way to get a little more juice out of it?

I mean if the 115 is a de-tuned 130 after all, what is needed to get that extra hp and make that extra rpm? I never found a solid answer but hear mixed opinions, some say carbs, some say reeds, some say the block is different, different porting etc.. Is there anyone who KNOWS what needs to be done, and not just suggestions?

The second part to this question is, if I can't make it a 130 is it possible to get a little more power out of it? Can the carbs be tweaked, changed or...?

If anyone has done this I would appreciate your response VERY much. Overall goal is to gain a few mph on the top end while improving mid range and over all performance. I am already hitting 49 but I would imagine another 15 ponies and another pitch or 2 more in prop should gain me some mph..?

Thanks,
Nick

 

[99yam40]

talk to someone from here to see what they say

http://www.shop.hydrotecmarine.com/main.sc


post what they tell you

 

[100333624]

talk to someone from here to see what they say

http://www.shop.hydrotecmarine.com/main.sc


post what they tell you

Thank you!

I sent them an email and we had a few emails back and forth. After checking them out further, it seems that they have a great reputation. Here is the text from our emails today:

Me: Hello, I'm looking at improving the performance of my outboard and I was wondering if you can help me.

I have a 1995 Yamaha 115 hp, it's a 2 stroke. Nothing is wrong with the engine, but I know Yamaha made a 130 that is practically the same engine. From my research, it seems to indicate that the 115 is a de-tuned 130.

Though when trying to find what parts are different or what would be needed to make my 115 into a 130, I seem to find only suggestions and no solid answer. Some suggest carbs, some say reeds, some say exhaust tuner, some say block is different, some say porting is different????

I can't seem to find the right answers and I was hoping maybe you'd know, or atleast point me in the right direction.

I look forward to hearing from you.


HydroTecMarine: carbs, tuner, block, heads, porting


Me: I'm from Toronto - Canada so I appreciate your quick response!??So pretty much everything is different then...??Ok so on your website you have phase kits but nothing for the 115/130, but you have all the mods for it separately???Maybe the kit isn't listed?

If I were to get a kit from you (head, reeds, exhaust tuner etc) what could I realistically expect in terms of hp increase???And would I need to change/upgrade anything else on the motor because of these parts, or will it be good to go?


HydroTecMarine:
HT 6750cf carbon fiber reeds $140
HT 8300 High Perf heads $400
HT 5115 tuner kit $336
main fuel jets $120

note: the 115 hp comes with 32mm carbs and the 130hp is 34mm, but I recommend not changing them or even boring them (not enough gain for money) with these mods you should see an increase of approx 40hp


Me: Great so I won't need to change anything else then right, just bolt those on and that's it????Can I still use 87 octane or will I have to use 91 after the mods???And do the heads come with gaskets and everything?

Also does it come with jets?


HydroTecMarine: actually we offer a HT 8300kit / heads with gaskets $558. The tuner comes with gaskets

91 would be best and I included jets in quote

-----------------------------------------------------------

That's it, I am waiting for a full quote with shipping to Canada which I should get in the morning. Am also going to research this a little deeper as I'm not familiar with all this, not sure if I can do the work myself, though I am handy and I've done some work on an old 80s mercury 80hp some years ago, removing powerhead and changed gaskets and such..

This would make a great winter project, and ~40hp increase would be insane if it's true. Already doing 49mph with a 20" Laser 2, prop calculator indicates I'll be 59-62mph if the numbers are correct running a 25" Laser 2 at 5-10% slip, crazy for a 16.5' fishing boat but that would be just lovely if its true.

 

[99yam40]

that old of a motor you may have trouble getting all the bolts to come out without breaking.
Not sure you can get enough air through the smaller carbs to go with the extra fuel by just changing the jets,
but what do I know

If you do get it beefed up be careful.
boats do not fly well.
Known of a few to take off and not land properly

 

[100333624]

that old of a motor you may have trouble getting all the bolts to come out without breaking.
Not sure you can get enough air through the smaller carbs to go with the extra fuel by just changing the jets,
but what do I know

If you do get it beefed up be careful.
boats do not fly well.
Known of a few to take off and not land properly

Ya I know what you mean.. The thing is it isn't a race boat, it's a wide deep V centre console, I don't think it will be too bad. As for the bolts, the engine hasn't seen much water in its life and spent most of its time on a stand, it's very clean inside and out for a 20 year old motor so I don't think I'll have a problem especially after taking apart a 35 year old motor with difficulty, this should be a piece of cake "hopefully"..

It's $1250 USD shipped, the thing is if I can do it myself or not. And also if anything else will be needed. Also will have to use high octane gas from now on $$$ but I get amazing mileage out of it already. There are a few things to think about.

 

[99yam40]

Yea, more HP mean more fuel has to be burned which means bad mileage.
That is the problem with beefing motors up plus the strain may make it come apart quicker

Heard of some shallow water flats boats catch air running fast that did not end good
And watched some drag boats go up in the sky too.
Had my 16' semi vee aluminum skiff front end with just a 35hp motor jump up and roll to the side when I was running into a storm front looking for shelter of the Inter coastal canal
Almost made it too, had to throw out the anchor and sit it out bailing water out of boat till the front passed

 

[100333624]

Yea, more HP mean more fuel has to be burned which means bad mileage.
That is the problem with beefing motors up plus the strain may make it come apart quicker

Heard of some shallow water flats boats catch air running fast that did not end good
And watched some drag boats go up in the sky too.
Had my 16' semi vee aluminum skiff front end with just a 35hp motor jump up and roll to the side when I was running into a storm front looking for shelter of the Inter coastal canal
Almost made it too, had to throw out the anchor and sit it out bailing water out of boat till the front passed

Ya I know what you mean... Although my boat is no lightweight drag boat, and no shallow flats boat, its a 16 footer and weights almost 1100 pounds dry so its by no means a light boat for its size. Max hp is 120 and I got a 115 on it, like I said I would imagine IF I could hit that extra 40 hp, I doubt it will be that high, then that would be great, if I can get another 10 mph out of it that would be awesome, though I know there is risk to blowing the motor up so there are some things to consider, although a flying boat is not one of them on my list yet as I really don't see that happening... We were hitting 4'' chop last week running almost 45 mph and we got wet but we didn't exactly go airborn as I used to with my 50hp and aluminum prop. My set up right now is actually VERY impressive and I am blown away at how the boat holds even in such choppy conditions.. My overall goal would be to gain a few mph, while going with the same prop but not too high of a pitch, but a little lower pitch and adding some more cup to it - it will be simply amazing. I am not looking at drag racing and dont get that idea, I am 29 years old, had spine surgery 4 years ago, have complications from that surgery too, and have physical problems as would any other normal person. I am not looking to fly, and I wouldn't be doing this or telling you this if I didn't think it was possible.

HOWEVER, if it turns out that its just way too over powered, good thing about it is you can always remove the parts and go back to stock since their bolt on parts right? OR, no use in pinning the throttle fully down...

Anyway I am a long ways from making a decision but it would be a nice winter project for me. I do appreciate your comments and thank you!!