Running-in

[HughN]

Over the last few weeks I've stripped-down and rebuilt the powerhead of my old Yamaha 30 (the same engine as the '689' Mariner version). Amongst the many new bits are new pistons and rings, running in newly-honed cylinders.

I was amazed when it started first time, ran quietly and smoke-free (even though I have halved the fuel:oil ratio). In fact, people will probably start saying "Ooh, my sewing machine runs as well as Hugh's engine"! )

The next step is running it in. I plan to run it carefully for about six hours, building up the RPM gradually during this time and not running at the same RPM for more than a minute or so. Does this sound about right?

(I am going to stick a piece of paper on the stern with 'Running-in. Please pass' written on it in Biro™...)

Cheers,

Hugh

[dave3235]

Originally Posted by HughN

Over the last few weeks I've stripped-down and rebuilt the powerhead of my old Yamaha 30 (the same engine as the '689' Mariner version). Amongst the many new bits are new pistons and rings, running in newly-honed cylinders.

I was amazed when it started first time, ran quietly and smoke-free (even though I have halved the fuel:oil ratio). In fact, people will probably start saying "Ooh, my sewing machine runs as well as Hugh's engine"! )

The next step is running it in. I plan to run it carefully for about six hours, building up the RPM gradually during this time and not running at the same RPM for more than a minute or so. Does this sound about right?

(I am going to stick a piece of paper on the stern with 'Running-in. Please pass' written on it in Biro™...)

Cheers,

Hugh

Hi hugh

I would look online for correct run in procedures for this engine to eliminate guess work,a digital tach would be ideal.

[9D280]

Try

Boatinfo - The library, containing manuals, brochures and other technical documents from the last hundred years!

- that's where I found the procedure for running in the Merc after I did much the same thing......

Failing that, I have a Mariner Clymer that may help, if you get stuck let me know the year of your engine & I'll see if the manual covers it.

[Maximus]

I know the old Mercs,and Yams I had and even e-tec recommended a little more oil in the mix when running in... Surely better to add a bit than hold back??

[HughN]

Originally Posted by Maximus

I know the old Mercs,and Yams I had and even e-tec recommended a little more oil in the mix when running in... Surely better to add a bit than hold back??

That's what I did. It is supposed to run at 100:1 but I halved the ratio to 50:1 (i.e, doubled the oil)

[A1an]

Personally, I'd just use it as normal taking care not to labour it or rev its nuts off.

There are a million and one "correct procedures" out there for running in an engine.

[HughN]

Originally Posted by 9D280

Try

Boatinfo - The library, containing manuals, brochures and other technical documents from the last hundred years!

- that's where I found the procedure for running in the Merc after I did much the same thing......

Failing that, I have a Mariner Clymer that may help, if you get stuck let me know the year of your engine & I'll see if the manual covers it.

Thank you. I'll do some digging...

[dave3235]

User manual will have the info in

[9D280]

Originally Posted by A1an

Personally, I'd just use it as normal taking care not to labour it or rev its nuts off.

There are a million and one "correct procedures" out there for running in an engine.

I suppose those procedures are maybe more important to be adhered to if you have warranty to worry about.

I just reckoned if I could find the appropriate one, then it would presumably be designed for my particular engine and be most appropriate. One thing is for sure with 2- strokes - doubling the oil for the first X hours is almost guaranteed!

[uncle al]

If it was my engine ,I would run it on a 50:1 mix all the time. as for running it in ,
Dont over rev it,
Dont let it labour
Dont rev it up over 1,200 rpm out of gear.

[HughN]

Originally Posted by uncle al

If it was my engine ,I would run it on a 50:1 mix all the time. as for running it in ,
Dont over rev it,
Dont let it labour
Dont rev it up over 1,200 rpm out of gear.

Given your expertise on these OBMs I'll take that as definitive!

[RIB-Teccie]

Here is an old Yamaha running in procedure from 1980. As you have rebuilt your engine I would dispense with the 25:1 unless your engine was an old 50:1 model, but I doubt it.

[HughN]

Brilliant - thank you!

That graphic is a great way of showing things too.

[RIB-Teccie]

So here's a bit of wisdom!

1) 1974 - You use a "babe" to advertise your wares to the dizzy heights of 25hp.
2) Your 25hp has no through hub exhaust and is 1:50.
3) By 1983, your 30hp is now through hub and 1:100.
4) Here's the Bombshell. We can only run our old Yamaha's on 2 Star Petrol!!

Shows how much I read the specs!!

All yams ran on 4 Star and Unleaded, so I don't quite know where that came from. Cheaper running or appealing to countries with lower octane fuel.

Bizarre!!

[HughN]

Originally Posted by RIB-Teccie

So here's a bit of wisdom!

1) 1974 - You use a "babe" to advertise your wares to the dizzy heights of 25hp.
2) Your 25hp has no through hub exhaust and is 1:50.
3) By 1983, your 30hp is now through hub and 1:100.
4) Here's the Bombshell. We can only run our old Yamaha's on 2 Star Petrol!!

Shows how much I read the specs!!

All yams ran on 4 Star and Unleaded, so I don't quite know where that came from. Cheaper running or appealing to countries with lower octane fuel.

Bizarre!!

"Get that woman out of the way - I want to see the [engine's] lower unit!"

[RIB-Teccie]

Clearly a photobomb from 1974