# Yamaha 70 hp 4 vs 2 stroke on HPX-T



## Tilly_Copano (Feb 12, 2017)

Looking for some input. I have a buddy that is willing to sell me he's pretty much brand new 70 for a great price and it only has 30 to 40 hours on it, it's currently a tiller but I assume I can convert it. I currently have an 02 2 stroke with about 375 hours. Would you make this swap? Would I see a performance difference? How much do you think my 2 stroke is worth? It runs great just serviced.


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## Smackdaddy53 (Dec 31, 2012)

I ran an fished off an HPX-T with a Yamaha F70 and it ran 36-37mph but holeshot left something to be desired after fishing off my current HPX Tunnel with a 2 stroke Yamaha 70 getting half a boat length hole shot and 32-33mph. It’s all about what you are willing to accept as a compromise. The 4 stroke is heavier and it’s noticeable when looking at the boat sitting in the water with no one in it, the boat is stern heavy. The 4 strokes have no balls AKA low end torque compared to their 2 stroke little brothers. The good is fuel economy is better and it’s quieter. In my opinion the perfect motor for an HPX-T is a 2 stroke Yamaha 70.


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## Guest (Sep 6, 2018)

Well Smack, I do believe that question was made to order just for you lol! I don’t think OP can get a better more informed reply!


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## Tilly_Copano (Feb 12, 2017)

I have got the boat tuned with the jackplate and cav plate. Hole shot is great and I can run skinnier than I want. Just debating if the 29 extra pounds of the 4 stroke will make that big of a difference and how much hole shot will I lose.


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## Smackdaddy53 (Dec 31, 2012)

Tilly_Copano said:


> I have got the boat tuned with the jackplate and cav plate. Hole shot is great and I can run skinnier than I want. Just debating if the 29 extra pounds of the 4 stroke will make that big of a difference and how much hole shot will I lose.


I’m sure others with real world time on both rigs will chime in and I won’t argue with them unless they make false statements or “I heard from a guy...”
I guess it all depends on what you want out of your boat. If you want to run further on less fuel, don’t mind losing a good bit of hole shot, some draft and want 4-5 more miles per hour go with the 4 stroke and a three blade Powertech (I can get you the exact model number from my buddy). I know for a fact that a 4 stroke Yamaha 70 can’t swing the same prop a 2 stroke 70 can so that says something. You have about 550 more RPM to play with but speed isn’t my concern as much as getting out of the hole and cutting in and out of winding creeks like an all wheel drive sports car. 
If you like less weight on the transom, the best hole shot, easy DIY maintenance, the robust smell of 2 stroke exhaust and don’t mind filling the tank more often the 2 stroke is probably your Huckleberry. It’s just tough to beat the power to weight ratio of a 70TLR in my honest opinion. I’ve never run an HPX-T or Tunnel with anything other than these two motors so I can’t speak intelligently about them but looking at weight specs vs actual horsepower I think the only other motor I considered hanging on my transom was a new Tohatsu 50 BUT I know a well know. local guide that has one and has had his Hell’s Bay towed in several times since he got it. I know several guys on here run them without issues (that we’ve heard about) but who knows.


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## hunterbrown (Feb 17, 2014)

I went from a 60 merc two stroke to a 60 merc four stroke on my hpxt. Speed ended up being almost identical and I had a foreman prop on it so holeshot was as good as it gets. If you want performance out of the hpxt an of the shelf prop isn't going to cut it. If you go with the four stroke have jack foreman build a prop for it and don't look back. If nothing is wrong with your engine and you aren't making really long runs in the glades or something it probably isn't worth the hassle of swapping engines, converting it to remote steering, and selling your old motor. That boat will squat some with no one on it and a four stroke on a jackplate.


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## Seymour fish (May 13, 2018)

Tilly_Copano said:


> I have got the boat tuned with the jackplate and cav plate. Hole shot is great and I can run skinnier than I want. Just debating if the 29 extra pounds of the 4 stroke will make that big of a difference and how much hole shot will I lose.


You can get the hole shot with an f70, but top end will be 32-33 tops. F70 jacked up is plenty loud. Not worth changing up a tuned boat for marginal gains/losses. Stay put. (Don’t take it to mean Smack is right or anything). Lmao


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## Vertigo (Jun 3, 2012)

The big difference is that the F70 plus tiller conversion will cost you thousands of dollars plus hours labor for very little or no gain.


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## SomaliPirate (Feb 5, 2016)

Swapping out a working two stroke for a four on a tunnel makes Baby Jesus cry. Don't make Baby Jesus cry.


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## nautilott (Oct 29, 2017)

SomaliPirate said:


> Swapping out a working two stroke for a four on a tunnel makes Baby Jesus cry. Don't make Baby Jesus cry.


^^^...SP, thanks for the coffee nasal enema. Damn dude!


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## Smackdaddy53 (Dec 31, 2012)

Vertigo said:


> The big difference is that the F70 plus tiller conversion will cost you thousands of dollars plus hours labor for very little or no gain.


Even if it were an even trade for a 4 stroke it wouldn’t go on my skiff...


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## jimsmicro (Oct 29, 2013)

The holeshot on the F70 sucks by comparison but top end will be about the same. But the F70 is sooo much smoother and quieter. Just depends really. If inches to plane out matter then stay two stroke. If economy, smooth easy starting, and quietness matter get the new motor.


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## devrep (Feb 22, 2009)

the hours on your current motor are nothing. don't put yourself thru this...


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## Redbelly (Jan 23, 2016)

Don't


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## DBStoots (Jul 9, 2011)

"the robust smell of 2 stroke exhaust"!


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## Anderson Guide Service (Feb 17, 2017)

I have an f70 on my and I can get it up if I am floating. I would not get rid of a working two stroke for a four stroke though. Having said that I will probably never go back to a two stroke.


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## Smackdaddy53 (Dec 31, 2012)

Anderson Guide Service said:


> I have an f70 on my and I can get it up if I am floating. I would not get rid of a working two stroke for a four stroke though. Having said that I will probably never go back to a two stroke.


I agree with you and have seen some shallow hole shots on my buddy’s with the F70 and no compression plate but it takes twice the distance to get on plane which means twice the prop scar. Hate to one up you but I can get up from sitting on bottom. Ed can attest, he was sitting on the front seat and witnessed it. I wouldn’t do it over grass but this time was over a silted in shallow pocket after hurricane Harvey last year. I ran us up in the back of this pocket and it kept getting shallower and I ended up cutting the wheel and skimming sideways in about 4” and the prop finally blew out. I poled her in 4-5” dragging bottom until I got to where the hull was barely on bottom and told him to hang on. 
A 6-7” holeshot is nothing to turn your nose up at but I’ll push the limit every time.


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## Anderson Guide Service (Feb 17, 2017)

I guess I have not been it the position of sitting on the bottom......yet


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## Smackdaddy53 (Dec 31, 2012)

Anderson Guide Service said:


> I guess I have not been it the position of sitting on the bottom......yet


I ran up on a 2” sand bar a while back because I was messing with my GPS and not watching where I was going. I love having a boat light enough to push off skinny sand and not have to call an airboat.


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## EdK13 (Oct 3, 2013)

Smackdaddy53 said:


> I agree with you and have seen some shallow hole shots on my buddy’s with the F70 and no compression plate but it takes twice the distance to get on plane which means twice the prop scar. Hate to one up you but I can get up from sitting on bottom. Ed can attest, he was sitting on the front seat and witnessed it. I wouldn’t do it over grass but this time was over a silted in shallow pocket after hurricane Harvey last year. I ran us up in the back of this pocket and it kept getting shallower and I ended up cutting the wheel and skimming sideways in about 4” and the prop finally blew out. I poled her in 4-5” dragging bottom until I got to where the hull was barely on bottom and told him to hang on.
> A 6-7” holeshot is nothing to turn your nose up at but I’ll push the limit every time.


I really did not think it would get up. That mud back there is like a suction cup. I kayaked to that same spot years ago and had to drag a T160 a good quarter mile through that same slop after the tide dumped..it sucked. Thought I might get to relive that ridiculous experience. Well - for my part this turned into a legit "hold my beer" moment. Skiff moved just a hair, Mac put the hammer down and it just popped up in maybe half a boat length. Mac has that Mav dialed in. 2 stroke torque coupled with that crazy bad ass foreman prop of his makes it all possible.


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## Smackdaddy53 (Dec 31, 2012)

EdK13 said:


> I really did not think it would get up. That mud back there is like a suction cup. I kayaked to that same spot years ago and had to drag a T160 a good quarter mile through that same slop after the tide dumped..it sucked. Thought I might get to relive that ridiculous experience. Well - for my part this turned into a legit "hold my beer" moment. Skiff moved just a hair, Mac put the hammer down and it just popped up in maybe half a boat length. Mac has that Mav dialed in. 2 stroke torque coupled with that crazy bad ass foreman prop of his makes it all possible.


And our combined weight back then was around 490#


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## Matts (Sep 2, 2015)

What Smackdaddy said!! The only plus for the 4S is fuel economy. I had a 2S yammie 60 on a tunnel and now a Zuke 60. The Zuke isn’t bad, for a 4S, but I’d take the 2S back any day and just carry extra fuel!!!!!!!


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## Bruce J (Mar 4, 2018)

I've had two Maverick HPX-T's, one with the 2-stroke, and now with the F70. The F70 is on a jackplate and the 2-stroker was not. Things I liked about the 2-stroke: pure low end guts, simple, very reliable, easy to pull start if necessary, provided it's already warm. The F70 is quieter, but I can't say I was ever bothered by the 2-stroke noise. It's smoother operating - more graduated throttle response vs. the more "all or nothing" of the 2-stroke (at least mine felt that way). It doesn't smoke - which matters depending on your preference for aroma! I think my hole shot is really better on my current boat, but that's more a function of the jack-plate and Foreman prop. Mac's set up with the 2-stroke and jack plate and Foreman is the best for pure performance. 

I didn't care about the mileage/efficiency either way as both just sipped gas. With either boat I worried more about getting through a tank of gas before it went bad. If you typically cover a lot of water, it would make a difference.


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