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70 hp yamaha on 17 montauk?
74monoriginal	#1  Posted on 09/09/10 - 3:31 AM
Member Posts: 4 Comments: 0 Joined: 09/05/10	This 17 I'm restoring is powered by a 2003 2stroke 70hp shortshaft. some folks I've talked to have said that it is sufficient enough for the boat. I've never run a montauk with less than a 90. Does anyone have an opinion on this and more importantly how it should be propped for best performance out of the hole and top end. I have never run this boat before as it was sitting for a while and the coil packs had been scavenged when I got it. I appreciate any advice. Also looking to buy a prop if you have one.
Fishmore	#2  Posted on 09/09/10 - 1:05 PM
Member Personal Page Posts: 270 Comments: 0 Joined: 11/20/07	The horsepower is okay but the short shaft will not work well. You need a long shaft motor on a Montauk. If you can do the work yourself I would get the motor running and then sell it and buy a new motor with the proper shaft length. if you need to pay someone to get the motor running then just sell it for parts.
faceinsert	#3  Posted on 09/09/10 - 2:50 PM
Member Posts: 9 Comments: 0 Joined: 10/10/09	When you say long shaft do you mean 20" shaft?
Joe Kriz	#4  Posted on 09/09/10 - 2:53 PM
Site Owner Personal Page Personal Album Photo Albums Project Albums Posts: 11447 Comments: 452 Joined: 03/18/05	Short = 15 inch Long = 20 inch X Long = 25 inch XX Long = 30 inch
whalersal	#5  Posted on 09/10/10 - 3:38 AM
Member Personal Page Posts: 100 Comments: 3 Joined: 04/19/05	I had a Yamaha 70hp two stroke on my Montauk before I re-powered. That engine is a great engine, and plenty powerful. My boat paces on Barnegat Bay in NJ, and it is rare that 40mph would be comfortable there, so the 35mph or so top speed was plenty fast. The engine is punchy. I was so happy with the horsepower that I didn't have reservations about re-powering with a 75 hp engine this past year.
CES	#6  Posted on 09/10/10 - 3:49 AM
Member Personal Page Photo Albums Project Albums Posts: 2681 Comments: 7 Joined: 04/27/07	The 70hp Yami is bullet proof. Be sure the shaft is the correct length or else you're wasting your time and money if you buy it. Cliff 1966 13' Sport with a 1993 40hp Yamaha 2 Smoker
chris galschjodt	#7  Posted on 09/10/10 - 7:30 AM
Member Personal Page Posts: 34 Comments: 1 Joined: 02/02/06	Hey I have a 70 horse Johnson Four stroke on an Eastport 17 and it works great. Chris
74monoriginal	#8  Posted on 09/13/10 - 10:42 AM
Member Posts: 4 Comments: 0 Joined: 09/05/10	Thank you everyone, It is not a short shaft afterall. It is the longshaft model. I have confidence that it will do the job. Thanks for all of the input.
themclos	#9  Posted on 09/13/10 - 1:06 PM
Member Personal Page Project Albums Posts: 81 Comments: 3 Joined: 12/11/05	I owned whalersal's Montauk before selling to Sal. I don't know what he means by the 35 MPH or so top speed. My son and I hit 40MPH one fine day with that boat. Of course, we were trying to beat a frontal system to port, and we paid the price as we bounced from wave to wave. Seriously though, the Yamaha 70HP motor is a great fit for the Montauk. Dan 1986 22 Outrage Cuddy, 2002 225HP Optimax
Joe Kriz	#10  Posted on 09/13/10 - 2:45 PM
Site Owner Personal Page Personal Album Photo Albums Project Albums Posts: 11447 Comments: 452 Joined: 03/18/05	themclos, No way a 70hp will push a Montauk 40mph over the water. You must have had a 5 mph current or wind at your back. 35 mph + 5 mph current or wind would equal 40 mph ground speed or GPS speed.
jaxmyth	#11  Posted on 09/15/10 - 9:15 PM
Member Personal Page Posts: 45 Comments: 2 Joined: 05/29/09	i have a 70 hp on my montauk. its an 88 two stroke. i get up on plane pretty quick and my top speed with loaded cooler and two people was 32 on gps. dont remember what the wind or current was doing, but i was satisfied nonetheless. pulls a tube fine, and i'm not fishing tournaments. although i must say,given the option, a 90 would be more fun. i just need to figure out a way to explain that to my wife
msd58	#12  Posted on 09/16/10 - 4:19 AM
Member Personal Page Posts: 115 Comments: 9 Joined: 04/08/06	My boat came with a 70 2 stroke Evinrude. I sold the motor got 90 YAMAHA. Bolted right up same weight as 70. 70 was good the 90 is better. I like it because often times I heavy loaded. However if a 70 is all you have you will be fine.
themclos	#13  Posted on 09/16/10 - 7:30 AM
Member Personal Page Project Albums Posts: 81 Comments: 3 Joined: 12/11/05	Joe, Lightly loaded, just my son and I, no bottom paint, speed measured on GPS on a lake with little to no wind, no current, using the standard Yamaha painted steel propeller. We hit 40 MPH on more than 1 occassion. Could never push beyond that. 35 MPH was easy. I am not arguing with you, just reporting what my instruments measured. I have seen other reports of this as well. Dan 1986 22 Outrage Cuddy, 2002 225HP Optimax
Fishmore	#14  Posted on 09/16/10 - 8:03 AM
Member Personal Page Posts: 270 Comments: 0 Joined: 11/20/07	Dan, I can see you hitting 40 mph assuming you are running a 17 pitch prop at 6000 RPM the calculated speed would be 38.97 mph so add a little current or wind at your back and it is possible. My Montauk with a 1994 Mercury 75 HP 2-stroke has a top RPM of 5250. Running a 19 pitch prop it does 38.5 mph and the calculated mph is 38.47 mph. I used the same calculator for your setup so would have no reason to doubt you can hit 39 mph. Personally, I have only seen 40 mph once when running full throttle going with a 3 mph flood tide. The Yamaha 70hp is 80 lbs lighter and 5 less HP but turns 750 rpm more at top rpm as compared to my Mercury. Edited by Fishmore on 09/16/10 - 8:30 AM
themclos	#15  Posted on 09/16/10 - 9:30 AM
Member Personal Page Project Albums Posts: 81 Comments: 3 Joined: 12/11/05	The main purpose for my post was to lend my opinion that the 70 HP 2-stroke Yamaha motor is a great power plant, and a great fit for the Montauk. I don't think anybody would be disappointed with it. I will never argue or quibble over a couple of miles per hour, because I think there are too many variables (as well as margin for error in electronic equipment) to be able to duplicate somebody's scenario. In my experience with the Montauk, there were very days where we were able to run for any length of time at 35 MPH or better, and these were typically in a lake environment. That's plenty fast in a Montauk, if you ask me. Dan 1986 22 Outrage Cuddy, 2002 225HP Optimax
Joe Kriz	#16  Posted on 09/16/10 - 12:17 PM
Site Owner Personal Page Personal Album Photo Albums Project Albums Posts: 11447 Comments: 452 Joined: 03/18/05	Everyone might want to take a look at this thread and the speeds people are getting with a 90hp on a Montauk. http://www.whalercentral.com/forum/vi...rowstart=0 40 to 44mph over the water speed is about tops for a 90. I'm certainly not arguing with anyone here but 40mph with a 70hp I can't ever see happening. I had a brand new Evinrude 70hp on my Montauk since the day I bought it and never could get close to 35mph. More like 32. However, my engine was mounted all the way down. I might have been able to squeak out another mile or two if the engine was raised to proper height. Yes, the older Yamaha 70 and 90 were good engines along with several other brands. Too bad they don't make them anymore and were never considered "Clean" engines just like all the other old 2 strokes. Edited by Joe Kriz on 09/16/10 - 12:33 PM