Rut Oh George

[BlkY2k]

I have 1990 Bayliner 1700 capri here that I got from the father in law. We`ve run it 2 seasons now and I thought I would change the impeller out this spring before using it. When I pulled the prop I found that it didn`t have a pin or a thrust washer on it, and the prop had slid back against the leg and got a little chewed. This is on a 1990 50 hp force motor, model 507x90d. I`ll post some pics of the prop, but I guess my question is, is this the correct prop? I dont have a tach on it so I`m not sure on rpms, I did gps it last year with 2 people, 2-6 gal tanks and 1 batt. 29 mph wot. The boat seems to do okay with 2 or3 people on board but thats it anymore and it wont plane at all and the 3rd person has to sit up in the bow anyways. Thanks guys.

In this one you can see the cup in the bronze washer and the groove in the back part of the prop.

And these are the #s on it.

It didnt seem to hurt the leg at all, it looks like the ss screws wore the groove in the prop.

 

[Scott Danforth]

Re: Rut Oh George

you need a new prop, your hub is coming out

 

[BlkY2k]

Re: Rut Oh George

Thats what I thought if you look at it from the end its cocked to one side. Reading the numbers its a 11 1/2 " pitch correct ?

 

[BlkY2k]

Re: Rut Oh George

Ok after going back and looking at the schematics it looks like this model doesnt have a thrust washer its built into the back of the hub. This one is gone, ground right off. GGGrrrr Now i gotta find a prop.

 

[steelespike]

Re: Rut Oh George

The prop is positioned by the pin if it seems to spin reasonably true put a pin in and use it.
On the other hand you might get a more up to date design in a new prop.If you can get us the gear ratio we may be able to tell if your set up seems to work.If you pull the plugs mark the flywheel and prop, count the flywheel rotations
for one revolution of the fly wheel.
Right, 11 1/2" pitch. New props are available here at boats.
Don't know what its rated for but at 50 hp it is underpowered so you may have difficulties as you add weight.As we progress we may be able to improve things a little with info from your end.

 

[BlkY2k]

Re: Rut Oh George

1 1/2 rotations of the flywheel for 1 of the prop. Thanks Steelespike for your help.

 

[steelespike]

Re: Rut Oh George

I know its a pain but could you double check the ratio.Seems very numerically low
Pretty sure Force used something below 2.00 but above 1.5. 1.6 to 1.9
Forces after 94 had a 2.00 based on the Merc lower.
Unfortunately we can't use the calculator without a for sure ratio.
You may have to mark the prop and flywheel and have an index mark to pinpoint
both item exact rotation.
In the mean time maybe someone will pop in with the info.
If your sure you have the count right we'll use it.

 

[BlkY2k]

Re: Rut Oh George

I`ll double check.

 

[Frank Acampora]

Re: Rut Oh George



No, You don't need to find a new prop. There never was a "built-in" thrust washer.

Here is an old school bronze prop--they can still be found on the auctions. This one is "pinned" because hubs for this prop are not available new and rarer than hen's teeth used.

Although splined to the shaft, that prop uses a stainless thrust pin to locate it fore and aft on the shaft. While the bronze hub does appear to protrude from the prop more than usual, the prop itself appears serviceable. Most of the times, the holes in the prop hub should be very close (1/16 or so) to the flat of the prop to properly locate the prop in relation to the shaft and gearcase.
Since the rubber hub is actually not as long as the cylinder inside the prop, it can easily be pressed in too far. Sometimes when I repair these props, I place a rubber spacer in the prop first to prevent the hub from working its way in too far.

Use an unthreaded piece of 1/4 inch diameter stainless bolt or buy a "shear" pin and try the prop.You will know right away if it has spun the rubber as the engine will rev and the boat will not go well. If you do not have the tailcone, buy one--It keeps the pin from flipping out. Secure it with a stainless cotter pin.

If the rubber cushion inside the prop has spun then you have three options: 1. buy a new prop. 2. repair and rehub this one (probably as costly as buying a new one and not very likely) or 3. "pin" the prop.

These props were all in odd increments--10 3/8 diameter by 11 1/2, 12 1/2, and 13 1/2 pitch. They might be available in lower pitches too but the 11 1/2 would be about the all-around choice. As far as performance, if the prop is NOT spun and you used to get 29 MPH, that is certainly not too shabby at all for that engine. Thus you need to check compression, fuel system, and ignition system for reasons for performance loss.

 

[steelespike]

Re: Rut Oh George

Great info Frank.Do you know what gear ratio he should have in that 1990 50 hp?
my info doesn't include the 50's for some reason.He counted the flywheel to prop and came up with 1.50 Seemed numerically low to me.
He was going to double check.

 

[BlkY2k]

Re: Rut Oh George

Okay, I marked the prop and the flywheel.

I turned the flywheel and it went all the way around and back to here.

So 1.6- 1.165??
I went and got some pins frank and put it back together, and it seems to fit snug. I didnt have any slip when I put it away last fall, but I`ll see what it does now that its pinned. The weather looks good for tomorrow and sat. I`ll see if I can sneak out tomorrow afternoon.

 

[steelespike]

Re: Rut Oh George

Good job pin looks good and ratio looks like about 1.60.
Now that its pinned maybe it will rev a little easier.
Ran the calculator 11.5 prop 1.60 ratio,10% slip 29 mph works out to about 4750 rpm.
speed is pretty respectable for a 50 Force on a 17 ft boat.
Try trimming in with a load,(prop closer to the boat).
Check that the throttle opens all the way and link and sync is right.
Maybe eliminate one tank with a heavy load.
There is a 10" pitch that should get you up to about 5000. Top would be about 26 but should plane easier with a load and get over the hump with an additional person.You may have to watch the rpm with a light load. I think the motor is rated for 5250..
Something like a Tinytach would really help for fine tuning the setup and to be sure you don't over rev.

 

[BlkY2k]

Re: Rut Oh George

Thanks for the input steelespike. I`ve been looking at tachs, did some research here. The Tiny tach looks like a decent setup for $47 and Great lakes skipper has a Faria for $54. I was going through the manual and I thought I saw operating range of 4500-5500 for the force, I`ll look again to be sure. I`ve read so much in the last couple of days its all kinda running together.lol

 

[steelespike]

Re: Rut Oh George

The nice thing with the Tinytach is you can use it on any motor. be sure to read all the info and order the correct antenna wire.
Your rpm rating is probably more up to date than mine.