V4 - Minimize Chances of Broken Rings

[Berdink]

I've read threads where ones say the V4's are prone to rings breaking - catching on the cylinder walls where there's openings.
.
Is there anything I can do to minimize that happening?
Like an additive like yamalube or mixing a stronger oil to fuel ratio, or....?

 

[jimmbo]

A lot of the Ring Problems were the Result of OMC moving the Rings closer to the Crown(top) of the Piston. Over Propping, resulting in a too low of Max WOT Rpm, and high Piston Temps adds to the problem. Wrong/Poor Oil can result in Carbon building up behind the Rings preventing them from expanding-contracting
Best ways to avoid/reduce the Risk, is Prop the Engine to run in the Upper Half of the WOT Range.
Use a Good TCW-3 Oil. Myself, that would be BRP or Mercury Oils(that should start an Oil War). Yamaha has some very good 2 Stroke Oils too
Regularly use BRP Engine Cleaner/Mercury Power Tune to remove Carbon from behind the Piston Rings.
Those Engines are Speced to run 50:1 if using Premix. If the Motor has VRO/MRO, the Pump will mix the proper amount of Oil into the Fuel

 

[racerone]

It is a fact that the rings will break at some time!----Simply due to the shape of the top ring.

 

[jimmbo]

It is a fact that the rings will break at some time!----Simply due to the shape of the top ring.

Those Wedge shaped Rings? I think they were call "Pressure Backed", at least by Evinrude. They were first mentioned in the 1970 Model Yr

 

[Berdink]

Do the Wiseco brand pistons fix this issue?
Is it worth upgrading to those in such an old motor?

 

[Mc Tool]

Those Wedge shaped Rings? I think they were call "Pressure Backed", at least by Evinrude. They were first mentioned in the 1970 Model Yr

Yeah , everyone else calls them keystone rings . Lots of motorbike have used them and the only real issue , apart from abuse ,was excessive wear allowing worn thin rings in worn oversize ring grooves to twist and jump out the exhaust port or override the locating pins and poke a ring end out of a port.
You can do stuff to minimise wear or prolong engine life but when its knackered its knackered .
Just use the boat and dont stress out over it ....if it sucks a kumera it wont do all cylinders at once and you'll make it home

 

[Berdink]

...clip...
Just use the boat and dont stress out over it ....if it sucks a kumera it wont do all cylinders at once and you'll make it home

If/when it happens to me, it sounds like many upgrade to Wiseco.

 

[Mc Tool]

If/when it happens to me, it sounds like many upgrade to Wiseco.

Wiseco sure are good slugs , I fitted s set of them to a 70hp Johnson that was melting pistons (bit of a story) ...and it ate them too .....no fault of the pistons . I think their biggest advantage is that they come in larger oversizes that the stock pistons which gives you a couple more "lifes" when rebuilding .

 

[Berdink]

Wiseco sure are good slugs , I fitted s set of them to a 70hp Johnson that was melting pistons (bit of a story) ...and it ate them too .....no fault of the pistons . I think their biggest advantage is that they come in larger oversizes that the stock pistons which gives you a couple more "lifes" when rebuilding .

I read somewhere, and it may be wrong, but thought I read that they dropped the top ring down a little on the piston making it possibly less vulnerable.

 

[racerone]

I have no idea why the stuck with the bad top ring design for 25 years.----Such an obvious defect.

 

[Berdink]

I have no idea why the stuck with the bad top ring design for 25 years.----Such an obvious defect.

So, I could run it until it breaks a ring, but don't I risk when the ring breaks it scouring the cylinder wall, or chipping a portion of a port?
.
We'll see how this motor ends up working out for me, and if I decide to stick with it rather than find a 70hp, I'll likely just do the upgrade during a winter.

 

[Berdink]

I've been watching outboarddad on YouTube because he has a lot of 'How To' content on Johnson's 70hp and V4's.
When he has a rebuild, he asks what oil they were using. He said the overwhelming biggest majority of rebuilds is ones that use a lower quality oil.
He says stick with manufacturer's recommended product.

 

[jimmbo]

I have no idea why the stuck with the bad top ring design for 25 years.----Such an obvious defect.

The engineer that came up with it, or the manager who approved it, likely climbed the Management ranks, and canceling the design would be admitting it was a Mistake, and we all KNOW, that Management NEVER makes Mistakes

 

[jimmbo]

I've been watching outboarddad on YouTube because he has a lot of 'How To' content on Johnson's 70hp and V4's.
When he has a rebuild, he asks what oil they were using. He said the overwhelming biggest majority of rebuilds is ones that use a lower quality oil.
He says stick with manufacturer's recommended product.

It will be a classic case of the Owner claiming "Oil is Oil". In their Ignorant mind(s), there is no difference between a Top Tier TCW-3 and a TCW-3 that barely meets the Spec.

 

[Berdink]

I

A lot of the Ring Problems were the Result of OMC moving the Rings closer to the Crown(top) of the Piston. Over Propping, resulting in a too low of Max WOT Rpm, and high Piston Temps adds to the problem. Wrong/Poor Oil can result in Carbon building up behind the Rings preventing them from expanding-contracting
Best ways to avoid/reduce the Risk, is Prop the Engine to run in the Upper Half of the WOT Range.
Use a Good TCW-3 Oil. Myself, that would be BRP or Mercury Oils(that should start an Oil War). Yamaha has some very good 2 Stroke Oils too
Regularly use BRP Engine Cleaner/Mercury Power Tune to remove Carbon from behind the Piston Rings.
Those Engines are Speced to run 50:1 if using Premix. If the Motor has VRO/MRO, the Pump will mix the proper amount of Oil into the Fuel

It looks like BRP (Johnson/Evinrude) 2-cycle oil is now owned by XPS.
I hope they don't start trying to maximize profits.

 

[Nordin]

I have read in prospects for OMC from mid 70.es and they highlights the keystone piston rings helps to rise the pressure from the rings to the cylinder bore in compression.
If that is true or not I can not verify that.
The problem is and Chrysler/Force have had the same problem with these keystone rings is that they are to close to the piston crown.
There are no meat between the top ring and the piston crown.
And as jimmbo says, to lean mixture, over prop, over reving and maybe low quality 2 stroke oil can cause ring failure.
Quality of oil is a hot subject, I buy TCW-3 2 stoke oil that meet the spec and is good for the wallet.

 

[Berdink]

For a 90hp V4 Crossflow the stock prop is a 3-blade aluminum prop with a 13-inch to 13-3/4-inch diameter and a 17-inch or 19-inch pitch.
.
The one I have now is 17 inch.
Going to 15 inch on my 90hp V4 Crossflow would put less load on the engine, correct?

 

[Mc Tool]

For a 90hp V4 Crossflow the stock prop is a 3-blade aluminum prop with a 13-inch to 13-3/4-inch diameter and a 17-inch or 19-inch pitch.
.
The one I have now is 17 inch.
Going to 15 inch on my 90hp V4 Crossflow would put less load on the engine, correct?

Yes , but so would driving your car around in 3rd gear
Keystone rings are a good thing but like any ring to close to the crown they are a bit exposed. Swings and roundabouts . Moving the ring closer to the crown helps reduce emissions and detonation . There were even rings that had part of their upper surface totally uncovered ...similar to a dykes ring but with the stepped up part not covered by the piston at all ....really old stuff

 

[Berdink]

Ha!