50 horsepower jet - Yamaha, Evinrude, or Honda

Discussion in 'Alaska Flyway Forum' started by bobshem, Jul 2, 2007.

  1. bobshem

    bobshem Senior Refuge Member

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    I intentionally ran at about 2/3 to 3/4 throttle to maximize fuel economy. I backed the throttle of of wide open to an engine speed that sounded quiet and smooth on the tiller.

    Data from my handheld Garmin.

    Going down river with the current:

    33.2 miles, average speed 22 mph, 1 hour 32 minutes, considerably less than one 6.6 gallon tank.

    Going up river against the current:

    32.1 miles, average speed 17 mph, 1 hour 53 minutes, slightly less than one 6.6 gallon tank.

    The overall average speed 19.5 mph.
     
  2. bigreid

    bigreid Moderator Moderator

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    That is pretty good mph and mpg! It is amazing what 3/4 throttle will do. Is your top speed around 30 with the 40hp jet?
     
  3. bobshem

    bobshem Senior Refuge Member

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    No, probably mid to upper 20s depending on the load and the wear on the impeller and sleeve.

    It seems to me that I got about 28 mph when the jet was first installed and the boat was empty. I had my Kenai cam installed. I also had the original three blade aluminum impeller in place.

    I think that the only time I'd see 30 is going down river empty.

    Side note: After I purchased a stainless four blade impeller I noticed that my hole shot is much better. I went to Alexander Creek loaded down with two 200 pound guys, a 70 pound dog, tent, cooler, ice, seven 6 gallon cans of gas, etc. I was impressed at how nicely the boat got on step. I expected the boat to dog and maybe even not get on step but I was pleasantly surprised when that didn't happen.

    The four blade stainless doesn't seem to help the top end, however.

    I'd like to get a tachometer to help monitor the wear on the jet.
     
  4. bigreid

    bigreid Moderator Moderator

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    Bob,
    Check out tinytach.com or something like that. I know the company name is tiny tach. Danny in the boat forum highly reccomends them and I will probably get one for each of my motors as 40 bucks seems pretty nice for a tach! Obviously not top of the line but they will get the job done.

    Did you get the SS impeller yourself or did you have J. Kim put it in?

    I am thinking of getting one as well, for less wear more than anything. I am guessing around $500 bucks or so, plus a new sleeve. I am thinking of the new composite sleeve that J. Kim reccommended.
     
  5. bobshem

    bobshem Senior Refuge Member

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    No. I put the sleeve and impeller in myself. It is an easy task, easier than repacking trailer wheel bearings.

    Buy your parts at A-1 prop and impeller repair on Dowling where it curves north. They have the best prices I could find, plus I am not sure where you can find a four blade stainless, except at A-1.

    The guy that owns the place seems to be a top-notch businessman.
     
  6. bigreid

    bigreid Moderator Moderator

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    Thanks Bob, I will have to stop by there. I used to do business there when Bob was the manager and haven't been there since the sale and move. I would like to get a SS impeller for my jet, just to keep down the wear, I think it will save time and money in the long run. I think my impeller and sleeve is pretty warn.

    Did you check out tiny tach??
     
  7. bobshem

    bobshem Senior Refuge Member

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    I am currently "on the road" in Toulouse France. I am accompanying my wife on a trip that she "won" from her job. My access to the forum is iffy for the next week or so.

    I will google Tiny Tach and see what I find.

    I think that the only decent way to assure good performance from an outboard jet is to do some GPS work and some Tach work immediately after you install a new impeller and sleeve. Once the sleeve wears or the impeller wears you will probably note a decrease in running speeds and an increase in RPMs. A significant change in top end or RPMs would signal time to reshim or replace parts.
     

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