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Yamaha 50 2 stroke no Tell Tale on muffs and no serial plate

C

CoreyTroy

New member
Hi just bought a used boat with a 50 yammy 2 stroke.
it is a 2001 model apparently.
1. When flushing with muffs, no water comes out the tell tale, but in use in the water it squirts water.
Is this a sign of a worn impeller?

2. The serial model sticker is missing. I have found that the outboard can be identified by a number on the block near the starter motor. How do i work out the motor details for parts etc by this number?

Corey
 
You start by giving us the numbers. Also, look at the CDI and tell us what the markings on it are.

If you plan on using the motor while having the muffs installed then that may be a problem. If you plan on only using the motor when the boat is in the water, and the motor runs just fine without over heating, then what is the concern with the impeller?

Now if I got a new to me old motor the first thing that I would do is probably replace the impeller.
 
Hi.

If you want to flush it, you should backflush it rather than use the muffs. If you don't have a backflushing adapter, I would install one. Not expensive and easy to do.

If you get a stiff stream when in the water at speeds slightly above idle, then I would guess your impeller is just fine.
 
rejesterd said:
Hi.

If you want to flush it, you should backflush it rather than use the muffs. If you don't have a backflushing adapter, I would install one. Not expensive and easy to do.

If you get a stiff stream when in the water at speeds slightly above idle, then I would guess your impeller is just fine.
Click to expand...
Is there any links to adding a backflush adapter to this outboard?
 
I don't think there are installation instructions for your specific engine, but they're all similar. The adapter is hooked into the water outlet line, as shown here:

https://www.crowleymarine.com/yp/DZ107587/bottom-cowling-2-f50tlr-2011-50hp

This is how it looks on my engine. The parts you'd need are:

6R3-12580-00-00 (the hose adapter)
6C5-24378-00-00 (the T-joint that connects the flushing hose into the cooling water exit hose)
6C5-24312-00-00 (the flushing hose)

There are other parts like the bracket and grommet if you want to really get fancy, but if you're creative enough, you shouldn't need them. You can always remove the flushing hose w/ the adapter and cap off that end of the T-joint when running it on the water.
 
rejesterd said:
I don't think there are installation instructions for your specific engine, but they're all similar. The adapter is hooked into the water outlet line, as shown here:

https://www.crowleymarine.com/yp/DZ107587/bottom-cowling-2-f50tlr-2011-50hp

This is how it looks on my engine. The parts you'd need are:

6R3-12580-00-00 (the hose adapter)
6C5-24378-00-00 (the T-joint that connects the flushing hose into the cooling water exit hose)
6C5-24312-00-00 (the flushing hose)

There are other parts like the bracket and grommet if you want to really get fancy, but if you're creative enough, you shouldn't need them. You can always remove the flushing hose w/ the adapter and cap off that end of the T-joint when running it on the water.
Click to expand...
That does not "backflush" the motor. What it does in allow for water to be added to the block at the bottom of the motor. The same place to which the water pump provides water. From there the water flows through the block in the normal direction of travel.
 
Last edited:
rejesterd said:
Hi.

If you want to flush it, you should backflush it rather than use the muffs. If you don't have a backflushing adapter, I would install one. Not expensive and easy to do.

If you get a stiff stream when in the water at speeds slightly above idle, then I would guess your impeller is just fine.
Click to expand...
That does not "backflush" the motor. What it does in allow for water to be added to the block at the bottom of the motor. The same place to which the water pump provides water. From there the water flows through the block in the normal direction of travel.
 
So am I correct in assuming, if one was to ‘Backflush’ an outboard, it would have to be done with motor not running? Else backflushing would be fighting the flow of the water pump impeller wouldn’t it?

What is the advantage of backflushing, compared to muffs?
Only thing I could think of is any debris entering the bottom vents may be washed back out rather than getting trapped at the tell tale. But you’d be best to remove the bottom vents to stop debris getting trapped there instead of coming out when backflushing anyhow I would think.
 
Sorry.. probably a better term is "static flushing". The main advantage is you don't have to run the engine. Water will be forced down back through the water pump housing (and through the fuel cooler in later models). So part of it is back-flushed, but not the engine block. But if debris was small enough to come in through the intake vents, it should go back out when static flushing.
 
CoreyTroy said:
Cheers for that.
Think you are spot on. There is no oil mixing option, he fuel/oil has to mixed in the tank.

I want add a tilt/trim switch to motor too as this model does not have it.
Click to expand...

Rewind.... Take 2.
I sent an email to Yamaha Au, after i advised them of the serial #.
They replied with, not a 2001 model but a 2002 50HET.
 
CoreyTroy said:
Rewind.... Take 2.
I sent an email to Yamaha Au, after i advised them of the serial #.
They replied with, not a 2001 model but a 2002 50HET.
Click to expand...

Interesting. I wonder where Yamaha Australia got their information. Yamaha Japan data indicates that it is a 2001 model year motor. See below.

If you are in Australia (or rather not in the USA) why did you come to a USA website asking for information about your apparently Australian motor? A 50HET is not a USA model. Equivalent of a USA model C50TLRZ.

Seems that you should have contacted Yamaha Australia first and never have come here.

5l88qp.jpg
 
Some of the Yamaha's have a water port on bottom side of lower unit above prop. If so duck tape over hole when running on muffs.
 
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