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  1. #1
    Petty Officer 1st Class cordell's Avatar
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    Default My 1987 Force 85 HP and its Propeller

    I am starting a thread here hoping one of you fellow Force owners have the same set up as me or close to it. I have a Bayliner 1990 Capri Bowrider. The boat measures close to 18 FT if you include the built on swim platforms. The max HP the boat calls for is 90, I have a 85 HP on it, 1987 Force to be exact. I hit a rock/concrete in the ship channel North of Trinity Bay Texas the other day. The prop has the numbers A625265 PS625 stamped on the hub. On the side of the prop it reads 13 <RP> 17, the number 7 looks to be stamped over another number as it is bigger than all the rest of the numbers. Then directly across from that stamping is the number 19 all by itself, small than the numbers above it though. My thoughts are it was a 19 and was reworked to a 17. Anyway my WOT was 4750 RPMs at 30 MPH with myself, wife, 2 small kids and full tank. Here is where is gets weird.... I found another prop that reads 15 C on the side and A665265 PS665 on the hub. I assume a 15 pitch that is cupped. I tossed it on my boat and went out. The numbers were as follows, WOT 4100 RPMs and 30 MPH with myself, half tank. I made another run as I had to make sure I read the tach right and yep 4100 RPMs with myself and my son, again 30 MPH. My speed is the same with BOTH props yet my RPMs seem to drop with a lower pitch prop, HELP!

    I am lost, all I thought I knew is gone out the window. I can add pics if needed...

    thanks'
    cordell

  2. #2
    Fleet Admiral jerryjerry05's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    If all you get is 4100 RPM with 2 different props??? How is the motor running?Do a compression/spark test.This rules out any possible problems.
    You should be revving up to 5500 optimum.
    625 is a 19P/c Not real sure about the other.Sure it's not 685 not 665?What condition is the 19? How about the 15? Answer this and get back to us.J

  3. #3
    Petty Officer 1st Class cordell's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    Motor is running fine..idles has good hole shot, reaches 30 mph as it has since I had the boat. Big boat for this motor, my thoughts is a 120 hp would be better though bayliner rated it at 90 hp...

    With the original prop (first pic) I was 4800 RPMs and 30 MPH. That is the prop I hit a rock/concrete with. It is beyond repair. It is stamped A625265 PS625 and look at the stamping on the side, you see the number 7 looks to be stamped over another number? Also the number 19 is stamped below but upside down in relation to other numbers....

    What has me really stumped is WOT is 5500 RPMs for this motor. I was at 4800 RPMs with the 17 pitch I figured putting the 15 C on would/should raise the RPMs NO?

    Below is Bad Prop 4800 rpm and 30 mph (hit rock/concrete)


    Here is the prop that is 4100 RPMs stamped 15 C but still has hole shot and 30 MPH just as before I hit the rock and switched props. It is stamped A625265 PS625 on hub/bearing. This prop is in fairly good shape. In fact it is in better shape than the above prop before the rock.

    This is prop that gives 4100 rpm and 30 mph

  4. #4
    Petty Officer 1st Class cordell's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    Quote Originally Posted by jerryjerry05 View Post
    If all you get is 4100 RPM with 2 different props??? How is the motor running?Do a compression/spark test.This rules out any possible problems.
    You should be revving up to 5500 optimum.
    625 is a 19P/c Not real sure about the other.Sure it's not 685 not 665?What condition is the 19? How about the 15? Answer this and get back to us.J
    I examined both props again...PS625 does come back as 19 pitch as you said. This is the prop that I messed up, the one with the 13 <rp> 17 stamped on it. But look closely and you will see the 7 in 17 appears to be stamped over the original 9 or 19. Also 19 is stamped below it.....

    The PS665 is in fact PS665, I can not find ANY info on this prop. The only thing is the 15 C stamped on the side. Examining the prop closer it looks like one of the blades is not machined the same as the other two. It looks more flat and not as curved if you will. Its hard to describe but it doesnt seem right. Even if one blade was/is off would that cause RPM to be lower than the 17 pitch (or 19, not sure due to stamped numbers) RPMs? I lost 700 RPMs between the 2 props!

  5. #5
    Fleet Admiral jerryjerry05's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    That 15c should have pushed your RPMs way up not down.
    Did you do the comp/spark test?
    Is the boat left uncovered with the plug left in?Possible soggy foam adding weight.Do the test and post your results,J

  6. #6
    Petty Officer 1st Class cordell's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    I was running fine when the broke prop hit the rock, I brought it in right after that. I went back out the next day with the 15 C. I have pulled each plug independently and when done the motor idles very rough, replace wire and idles fine. I havent done a compression but will do if you think that might be the issue. My thoughts are the 15 C would raise RPMs as well, should that 15 C be a tighter shape. It is almost like the blades are straight out. And if compression was low or no spark wouldnt I drop in speed as well as RPMs? I still hit 30 MPH (gps) as fast as I did before. This has got me all messed up! lol I did not buy either of these props new, they are both used with no prior history known...

  7. #7
    Seaman
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    Default Re: My 1987 Force 85 HP and its Propeller

    I wonder if the "cupping" on the 15 pitch has anything to do with your lower RPM's.

  8. #8
    Petty Officer 1st Class cordell's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    I bought a compression tester this morning and was stressing the results all day! Well here they are.....

    1. 119
    2. 122
    3. 120


    WoW! That is FAR better than I hoped they would be! Still I have a issue, it has to be that prop That 15 C must be way out of wack or something, right? The day before I messed the 17 stamped prop up I was 4800 RPMs 30 MPH. Broke prop and went straight in and came out the very next day with this 15 C prop and dropped RPMs to 4100 but still 30 MPH. I know it dont make any sense, but its what it is.

  9. #9
    Petty Officer 1st Class cordell's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    Quote Originally Posted by Mark9740 View Post
    I wonder if the "cupping" on the 15 pitch has anything to do with your lower RPM's.
    The thing is they dont look cupped. They look almost straight, one of the blades is straight. Both props are a bit shady, the one I messed up was a 19 originally, modified to a 17. That 15 C should have raised my RPMs and lowered them instead. No Clue For all I know is the 15 C could have turned into a 21 pitch! lol

  10. #10
    Petty Officer 1st Class milehighboater's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    Do you know anyone with a prop you could borrow? I have to say the 17 sounds about right for your boat.

  11. #11
    Fleet Admiral jerryjerry05's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    They don't have to have a curve in them to be cupped.Like mile says get a different prop.A 17 should give good performance.
    Some dealers have used props laying around.If you tell them the story and you'll buy one from them, they might loan you one to test with.J

  12. #12
    Petty Officer 1st Class cordell's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    Well here it is, my Michigan Stainless Steel 17 pitch prop! It arrived 15 minutes ago. The only drawback is I have to go into Houston in about a hour, and when I do get home my wife has my truck at work She drove it to her work because it is 6 miles from the house. Houston is 35 miles, got to conserve gas so I got her car, a 4 banger chevy. I wanna hit the river! lol First thing in the morning I will get some fresh numbers and report on my new prop.

    Thanks Everyone
    cordell


  13. #13
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    Default Re: My 1987 Force 85 HP and its Propeller

    Dat sho am purdy! Now you're going to have to take it with you every time you leave the boat

  14. #14
    Petty Officer 1st Class cordell's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    Quote Originally Posted by foodfisher View Post
    Dat sho am purdy! Now you're going to have to take it with you every time you leave the boat
    Is that to prevent theft? I have my boat at the house on 1 1/2 acres. Although that didnt stop thieves from back up to my shed, busting the lock and running off with about $5000 in tools! Since then I have got a alarm for my home, shed, and a security camera that points towards the shed and my boat. I HATE THIEVES! I will be taking it off after every outing though, lol.

  15. #15
    Petty Officer 3rd Class eight tracker's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    Ummm,i think i can help you with that prop problem,just send along that SS prop and i will give you a report on how it works with my 1985 85hp force on my 16ft fish&ski sorry i don,t have a tach but i can give you mph readings while out on the water,oooh pretty shiny props can,t help myself...... aaahhhh.

    tom

  16. #16
    Petty Officer 2nd Class thompy's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    do you have a gps for mph, i know my speedo is very inaccurate, i have a nice 15c i was told extra cup, but my stainles 21 comes out of the hole much faster than the 15, have to get top speed # this weekend with the 21 and the gps, i run 39mph with the 15 at 5500rpm, this hasnt mad any sence to me
    UP, Menominee/Marquette

  17. #17
    Petty Officer 1st Class cordell's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    LOL My truck is back home with the trailer already hooked up. All I need is the sun to come up! Got tach and GPS for speed. I hope this pitch does the trick

  18. #18
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    Default Re: My 1987 Force 85 HP and its Propeller

    Zoom zoom

  19. #19
    Petty Officer 1st Class cordell's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    I am Ear to Ear Smiles


    I went out for a test run this morning. I hit 5000 RPMs WOT and 33 MPH, I have NEVER went that fast! I was taking corners like never before either! This prop is AWESOME to say the least. My only concern is when I installed the stainless prop I tightened the prop nut as far as it could go, but the prop was able to slide back and forth. I would guess it is 1/8 to 3/16 of a inch play in it. Is this normal? I was so worried I would spin that prop nut and loose my prop! I could literally close my eyes and see my prop flying through the air, lol. Is there something I need to do to eliminate the play in the prop or is this OK?

    Thanks
    cordell

  20. #20
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    Default Re: My 1987 Force 85 HP and its Propeller

    The play doesn't come into playgoing forward. Don't know if it will work the nut loose in reverse. Making a lot of turns to retreive your cap?

  21. #21
    Petty Officer 1st Class cordell's Avatar
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    Default Re: My 1987 Force 85 HP and its Propeller

    Quote Originally Posted by foodfisher View Post
    The play doesn't come into playgoing forward. Don't know if it will work the nut loose in reverse. Making a lot of turns to retreive your cap?

    LOL You could say that! I dont ride reverse much, only docking/trailering and what not. So I guess I will not worry about it. Only thing I could even do would be to add a lock washer. The prop nut, no the prop shaft doesnt have enough threads to snug it down all the way.

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