Calling Mr. Cosworth Vega

[Mike Cobine]

Re: Calling Mr. Cosworth Vega

The difference is not that it is abnormal, but the noise is masked.

In normal operation, any knocking would be every other stroke. In a case where a cylinder isn't firing at all (as opposed to a misfire), the knock would be every stroke. It would take very good ears to discern a knock on one stroke from a fire on the next. However, no firing would have a knock each time and nothing masking it.

And in some vehicles, you pull your foot off the gas on a hill, you can hear it, if you know what you are listening to. I've heard them rattle like a diesel.

The vacuum on a normal intake stroke with throttle open and with the throttle closed is a lot. NEVER downshift and use engine braking with aluminum rods.

Yet Aluminum rods survive use fine under acceleration.

In the firing stroke there is no intake of air so the vacuum is stronger than on the intake stroke.

As to Duke's comment on the oil pressure holding the bearing, it is true, normally oil pressure never lets the bearing contact the crank. If it does, damage is nearly immediate.

However, engine can and do run with spun bearings. I have seen engiens where the lower and upper insert are on the same side. And I have seen them so thin from spinning that Plastigauge is thicker. Yet the engine runs.

Most depends on the speed. Metal contact at 7000 rpm is disaster. At 500 rpm and Ol' Jim the junk man in his '54 Ford PU is probably not even noticing it.

And Ol' Jim's truck probably has 50,000 on the last oil change and about .006 clearance on the bearings. And along with that, he problaby has 8 psi of oil pressure, just enough the light doesn't come on. Or maybe the light is burned out.

You do this in your Vette, and you are toast on the side of the road. But somehow ol' Jim will drive this truck the next five years this way.

I've seen it far too many times.

But none of this really applies, as he has clarified it as a Goldwing. Whole 'nuther world.

[Mike Cobine]

Re: Calling Mr. Cosworth Vega

The difference is not that it is abnormal, but the noise is masked.

In normal operation, any knocking would be every other stroke. In a case where a cylinder isn't firing at all (as opposed to a misfire), the knock would be every stroke. It would take very good ears to discern a knock on one stroke from a fire on the next. However, no firing would have a knock each time and nothing masking it.

And in some vehicles, you pull your foot off the gas on a hill, you can hear it, if you know what you are listening to. I've heard them rattle like a diesel.

The vacuum on a normal intake stroke with throttle open and with the throttle closed is a lot. NEVER downshift and use engine braking with aluminum rods.

Yet Aluminum rods survive use fine under acceleration.

In the firing stroke there is no intake of air so the vacuum is stronger than on the intake stroke.

As to Duke's comment on the oil pressure holding the bearing, it is true, normally oil pressure never lets the bearing contact the crank. If it does, damage is nearly immediate.

However, engine can and do run with spun bearings. I have seen engiens where the lower and upper insert are on the same side. And I have seen them so thin from spinning that Plastigauge is thicker. Yet the engine runs.

Most depends on the speed. Metal contact at 7000 rpm is disaster. At 500 rpm and Ol' Jim the junk man in his '54 Ford PU is probably not even noticing it.

And Ol' Jim's truck probably has 50,000 on the last oil change and about .006 clearance on the bearings. And along with that, he problaby has 8 psi of oil pressure, just enough the light doesn't come on. Or maybe the light is burned out.

You do this in your Vette, and you are toast on the side of the road. But somehow ol' Jim will drive this truck the next five years this way.

I've seen it far too many times.

But none of this really applies, as he has clarified it as a Goldwing. Whole 'nuther world.

[Mike Cobine]

Re: Now that you've mentioned that it's a Gold Win

Chuck, the odds are the rattle you hear isn't a bearing noise at all, since the gear case is right under the crank. When you lose the power on that one stroke, everything is pulsing in the engine/transmission assembly and there is so much that rattles in a Wing, it is amazing they are as quiet as they are normally.

But an old one, they rattle. My '82 has around 120,000 on it without a rebuild other than valves and belts after an idiot in NJ hit me and took out the timing belt, pretzeling the valves.

If it is the left side, then this is normal. There is so much oil seepage when on the side stand that you have times you wonder if either left cylinder is firing. When first starting, I'd swear that is it getting ready to seize the way it lurches in the first few minutes while the oil burns out.

Run it how it was intended. Mike is right. A few runs up the RPM range will do wonders for it, and you. The Gold Wing was a performance bike. It was big, lots of power, and built to last. It wasn't the 750-4 performance but initially it was a hot bike, a lot like a big engine in an intermediate car.

But its durability made it a natural for long distance tourers who then added tons of storage because it had the power to handle it and it evolved into a Cadillac on two wheels for a lot of old people.

The new Wing is a bit of a return to its roots, with more sport handling.

Most think they aren't performance, because that old Wing of yours, like mine, has ancient frame technology that essential holds the motor between two wheels, and not very well with the hole in the side so the engine can come out. But that motor was built to perform.

Don't dog it.

[Mike Cobine]

Re: Now that you've mentioned that it's a Gold Win

Chuck, the odds are the rattle you hear isn't a bearing noise at all, since the gear case is right under the crank. When you lose the power on that one stroke, everything is pulsing in the engine/transmission assembly and there is so much that rattles in a Wing, it is amazing they are as quiet as they are normally.

But an old one, they rattle. My '82 has around 120,000 on it without a rebuild other than valves and belts after an idiot in NJ hit me and took out the timing belt, pretzeling the valves.

If it is the left side, then this is normal. There is so much oil seepage when on the side stand that you have times you wonder if either left cylinder is firing. When first starting, I'd swear that is it getting ready to seize the way it lurches in the first few minutes while the oil burns out.

Run it how it was intended. Mike is right. A few runs up the RPM range will do wonders for it, and you. The Gold Wing was a performance bike. It was big, lots of power, and built to last. It wasn't the 750-4 performance but initially it was a hot bike, a lot like a big engine in an intermediate car.

But its durability made it a natural for long distance tourers who then added tons of storage because it had the power to handle it and it evolved into a Cadillac on two wheels for a lot of old people.

The new Wing is a bit of a return to its roots, with more sport handling.

Most think they aren't performance, because that old Wing of yours, like mine, has ancient frame technology that essential holds the motor between two wheels, and not very well with the hole in the side so the engine can come out. But that motor was built to perform.

Don't dog it.

[Mike Cobine]

Re: Calling Mr. Cosworth Vega

At high revs the greatest bearing load is at the top of the exhaust stroke since there is no compression or combustion pressure to offset the inertial tension load on the rod as the piston goes over the top.


I think you might want to run the math on this again. If this were true, aluminum rods would rip apart as they do under engine braking conditions. But the force is much greater with shutting the throttle on the intake than the force at the top of the exhaust stroke.

The pressure in ignition is so great that if it increases slightly, tops of pistons are blown out.

Pre-ignition cracks pistons and blows out rings, but the force on the top of the exhaust stroke does neither.

Yet no one hears of pistons pulling themselves apart on the exhaust stroke.

And while you can say it is ease of manufacturing, it is no accident the oil passages exit the journal near the top of the journal for the compression and the ignition stroke. This allow that hydrodynamic pressure of the oil to be maintained under the heaviest load on the journal. They are typically offset from dead center so that if the bearing is forced to metal-to-metal contact, the opening isn't closed off and can recover the spacing rapidly because the load bearing pressure exerted by one 1/4 inch hole is not even close to the pressure exerted by the wide spread of oil in the bearing.

If the greatest load was at the top of the exhaust stroke, the opening would be near the bottom of the journal.

[Mike Cobine]

Re: Calling Mr. Cosworth Vega

At high revs the greatest bearing load is at the top of the exhaust stroke since there is no compression or combustion pressure to offset the inertial tension load on the rod as the piston goes over the top.


I think you might want to run the math on this again. If this were true, aluminum rods would rip apart as they do under engine braking conditions. But the force is much greater with shutting the throttle on the intake than the force at the top of the exhaust stroke.

The pressure in ignition is so great that if it increases slightly, tops of pistons are blown out.

Pre-ignition cracks pistons and blows out rings, but the force on the top of the exhaust stroke does neither.

Yet no one hears of pistons pulling themselves apart on the exhaust stroke.

And while you can say it is ease of manufacturing, it is no accident the oil passages exit the journal near the top of the journal for the compression and the ignition stroke. This allow that hydrodynamic pressure of the oil to be maintained under the heaviest load on the journal. They are typically offset from dead center so that if the bearing is forced to metal-to-metal contact, the opening isn't closed off and can recover the spacing rapidly because the load bearing pressure exerted by one 1/4 inch hole is not even close to the pressure exerted by the wide spread of oil in the bearing.

If the greatest load was at the top of the exhaust stroke, the opening would be near the bottom of the journal.

[Chuck R.]

Re: God I love This Board So

Thanks for the great feedback fello...uh Corvette enthusiests?

I picked the bike up for a grand (fully dressed) with a true 38,000 on the odometer.

The problem was that it had set unattended for almost three years, so I'm sure some not so nice internal issues might have possibly started.

It's fun to watch the volt meter drop like a stone at a red light with all the running lights blazing

I'm going to inspect the timing chains and if they're ok, I'll just run it till it talks louder to me!

Your all great sports for contributing to my on-going mechnical saggas.

Chuckster

[Chuck R.]

Re: God I love This Board So

Thanks for the great feedback fello...uh Corvette enthusiests?

I picked the bike up for a grand (fully dressed) with a true 38,000 on the odometer.

The problem was that it had set unattended for almost three years, so I'm sure some not so nice internal issues might have possibly started.

It's fun to watch the volt meter drop like a stone at a red light with all the running lights blazing

I'm going to inspect the timing chains and if they're ok, I'll just run it till it talks louder to me!

Your all great sports for contributing to my on-going mechnical saggas.

Chuckster

[Michael W.]

Re: God I love This Board So

It's not the timing chains we're discussing. It's the hyvo chain that goes from the crank to the clutch/transmission. Not accessible without major disass'y and not worth doing IMHO.

As an aside, the (valvel) timing chains are not chains at all, but rubber belts. Very reliable and rarely in need of adjustment.

Mike

[Michael W.]

Re: God I love This Board So

It's not the timing chains we're discussing. It's the hyvo chain that goes from the crank to the clutch/transmission. Not accessible without major disass'y and not worth doing IMHO.

As an aside, the (valvel) timing chains are not chains at all, but rubber belts. Very reliable and rarely in need of adjustment.

Mike

[Michael H.]

Re: Calling Mr. Cosworth Vega

If a bearing noise/rap could be heard at TDC on the compression stroke without the cylinder firing, it would be even more noticeable in the next cycle where there would be a total change from a positive pressure to a negative pressure as the piston passed through TDC. In the compression/firing cycle, there's pressure in the cyl at all times including the time after the piston passes through TDC and all the to the point where the exhaust valve leaves it's seat, even if the cylinder isn't firing at all. The overlap cycle would have even more reason to cause the change in inertia as there is no cylinder pressure assisting the change in it's direction. If a bearing were to make noise, it would more likely make that noise in overlap, not comp. because there is less resistance to the change in inertia. If no bearing noise can be heard with the cyl firing properly, there is no reason why it would occur at all even if the cyl wasn't firing.

[Michael H.]

Re: Calling Mr. Cosworth Vega

If a bearing noise/rap could be heard at TDC on the compression stroke without the cylinder firing, it would be even more noticeable in the next cycle where there would be a total change from a positive pressure to a negative pressure as the piston passed through TDC. In the compression/firing cycle, there's pressure in the cyl at all times including the time after the piston passes through TDC and all the to the point where the exhaust valve leaves it's seat, even if the cylinder isn't firing at all. The overlap cycle would have even more reason to cause the change in inertia as there is no cylinder pressure assisting the change in it's direction. If a bearing were to make noise, it would more likely make that noise in overlap, not comp. because there is less resistance to the change in inertia. If no bearing noise can be heard with the cyl firing properly, there is no reason why it would occur at all even if the cyl wasn't firing.

[Roy B.]

Re: Calling Mr. Cosworth Vega my head hurts

Now I know more then I ever wonted to know, my head hurts

[Roy B.]

Re: Calling Mr. Cosworth Vega my head hurts

Now I know more then I ever wonted to know, my head hurts

[Duke W.]

Re: Calling Mr. Cosworth Vega

I have done a rod bearing load calculation through 720 degrees of rotation - the full four stroke cycle - for a high revving engine at maximum design revs.

Just wondering - has anyone else ever done this? If not I can tell you that it doesn't look like what your intuition might lead you to believe.

The difference in load between the exhaust stroke and the compression stroke at closed throttle is at the noise level. You're looking at the load delta of 10 psi times piston area compared to an inertia load of SEVERAL THOUSAND of pounds!

Duke