cbmischler Posted April 28, 2020 Report Share Posted April 28, 2020 I have a 2006 HPX 17 with a Yamaha 115 2 stroke. I am thinking about repowering with a 4 stroke Yamaha 90 or 115. Would like feedback/opinions on the following 1.Any issues with the new engine ( 4 stroke 90 or 115) fitting under the poling platform 2.Is there a big difference in speed performance between the 90 and 115. Draft is somewhat important and I don't make long runs so top end isnt the most important thing to me Any feedback would be greatly appreciated Thanks Chip Quote Link to comment Share on other sites More sharing options...
polliwog Posted April 28, 2020 Report Share Posted April 28, 2020 why make the change unless you don't trust the 110 2 stroke? I have a 90 17ft Montauk whaler and it's a great combo,so I think if you decide to go for a 90 4 stroke it will be fine. You can also go to a SHO 90 which has extra umph. I don't know the weight difference between the 115 and 90 4 strokes,but it's easy enough to get that info. If you are interested in shallow keep the extra weight off the stern. I remember when I repowered the Montauk the weight difference was substantial for a small boat. Quote Link to comment Share on other sites More sharing options...
Coto Posted April 28, 2020 Report Share Posted April 28, 2020 I have a 115 2 stroke on mine and I won't get rid of it unless it dies. I think your better off with the 70 four stroke which I believe is 100 lbs less than the 90 and the 75 four strokes. The 70 has some impressive numbers for its horsepower/weight ratio. I had an hpx with a F90 four stroke at one time and I was not impressed with that combo it was heavy on the stern and the best I got out of it was 39-41 with a PTR 19 prop. If you don't care about speed and do care about the draft then the F70 is real hard to beat. My choice would be the F70 which is what I would replace mine with if it ever blows up. 1 Quote Link to comment Share on other sites More sharing options...
chad1616 Posted April 28, 2020 Report Share Posted April 28, 2020 Only my second time playing with the boat since I repowered with a 115 sho from a 90 2stroke. It’s definitely *** heavy hopefully when I add the trolling motor batteries to the front it will even it out. This motor is insane on this skiff For lots of different reasons the torque from the motor at 35 miles an hour will set you back, But I’m going to agree with Coto , 70 It is more than sufficient. Quote Link to comment Share on other sites More sharing options...
cbmischler Posted April 28, 2020 Author Report Share Posted April 28, 2020 Thanks for all the feedback. I hadn't considered the 70 HP but might need to add that to the mix. My 2S 115 is starting to come to the end of its useful life thus the need to repower Quote Link to comment Share on other sites More sharing options...
jason p Posted May 3, 2020 Report Share Posted May 3, 2020 Buy this, put $10K in your pocket. Drain the carbs, spray a little oil into the cylinders and keep it in your garage until your 115 blows up. Be faster and draft less than a 70 or 90 4 stroke, You’ll have the greatest mid-range skiff motor ever produced and the best motor for this hull. 2 Quote Link to comment Share on other sites More sharing options...
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