82 GS750E ?s I am now scared

[rapidray]

Look, I used to road race the plain bearing 750s & they are DIFFICULT to make live in anything other than a docile street life. Even then they can spin bearings & eat rocker arms & cams because the oiling system on THAT engine is a BAD DESIGN! Your bike looks to be in great shape so ride it till it spins a bearing, or eats the cams or rocker arms, & then BOLT in an 1100 or 1150 motor. Then you WILL have a bullet proof engine & will be HAPPY with the results!
Ray.

 

[posplayr]

Look, I used to road race the plain bearing 750s & they are DIFFICULT to make live in anything other than a docile street life. Even then they can spin bearings & eat rocker arms & cams because the oiling system on THAT engine is a BAD DESIGN! Your bike looks to be in great shape so ride it till it spins a bearing, or eats the cams or rocker arms, & then BOLT in an 1100 or 1150 motor. Then you WILL have a bullet proof engine & will be HAPPY with the results!
Ray.

And with he will have a built in $50 discount against his future 1100 purchase (750 oil pump gears)

 

[Guest]

Do most of u think it will be OK? to like 50k if its maintained...i really dont want to sell it

Run Shell Rotella 10w/30 or 15w/40, change oil & filter every 1500/2000 miles and you will get many years & miles out of it!! Don't worry about what some idiot at a bike night might say!!! The folks here on GSR know a lot more!!

 

[JEEPRUSTY]

Gosh speaking of idiots a guy went to buy my buddies Concours last week and started to try and beat him down by saying that I4 engines were on the way out and passe. Said the new twinslike in the Honda 750 were the wave of the future.

 

[Steve]

Thicker oil will build pressure better, I would run 15w-40 Shell rotella if it was mine.

True, but it's not pressure that lubricates the engine. :-k

What lubricates the engine is VOLUME. When the pump provides more volume than the lubrication passages can handle, pressure builds up. If you were to totally block the entrance of the oil passages, your pressure would be WONDERFUL, but with no oil getting to the bearings, your engine life will be dramatically SHORT.

Unless you live in, and only operate the bike in, a warm climate, I would use something with a smaller number on the front of the viscosity rating. The thinner oil (10w-whatever or 5w-whatever) will flow easier when the engine first starts up, which is when most of the engine wear occurs.

Run Shell Rotella 10w/30 or 15w/40, change oil & filter every 1500/2000 miles and you will get many years & miles out of it!! Don't worry about what some idiot at a bike night might say!!! The folks here on GSR know a lot more!!

Well, MOST of them know better, but I would not trust advice from somebody who recommends 30-weight oil.

Yes, 30-weight oil will flow easier, but there are limits to what it can do to protect the bearings. Suzuki recommended 10w-40 for a reason. Oils have gotten a bit better over the years, but there is still a difference between 30- and 40-weight oil.

My personal preference would be Rotella T6 synthetic, which is 5w-40.

.

 

[posplayr]

Steve,
Before you posted this, I was contemplating the point you made but was not willing to interject such a comment as I was unsure. Now that you boldly claimed what I was initially thinking(but unsure), I took a few moments to think and research it and now write a response

True, but it's not pressure that lubricates the engine. :-k
.

If you mean gauge pressure that might be true. However as I'll describe below, I'm starting to conclude that it is a direct indicator of lubrication for an OEM designed lubrications system, other than your blocked lubrication example, for a given system, if there is higher gauge pressure then there is higher bearing pressure. This would include higher pressure due to changing pressure 1.) pump gears, 2.) increased viscosity, 3.) higher pump flow rate,

What lubricates the engine is VOLUME. When the pump provides more volume than the lubrication passages can handle, pressure builds up. If you were to totally block the entrance of the oil passages, your pressure would be WONDERFUL, but with no oil getting to the bearings, your engine life will be dramatically SHORT.
.

This statement is correct in some respects, but as stated tends to be misleading. Increased flow rate, increases pressure, which is does provide increased lubrication. In your example, you have drastically altered the lubrication system so the pressure reading means something different entirely and I don't see how it is really relevant other than to indicate that you have to do an analysis of how gauge pressure and hydrostatic pressure are related.

See the link from Wikipedia below. Lubrications systems of Class I.
http://en.wikipedia.org/wiki/Plain_bearing
A hydrostatic bearing is lubricated by static pressure at the bearing between the journal and the bearing. So the question becomes what is the relationship between the bearing pressure and the gauge pressure for what is essentially a system with many parallel paths to the various portions of the engine requiring lubrication (some bearing some not).

Electrical analogies work very well in describing hydraulic flows and pressure drops. The first order linear models directly account for "dynamic fluid viscosity". For the moment the complexity of multi viscosity oils is not clear, but it probably has the expected effect of changing all of the flow resistance value in proportion to the viscosity.

Assuming you do not alter the flow by adding additional paths you can assume that if at the gauge you have lower pressure than before, there will be lower pressure any place downstream in direct proportion to the ratio prior to the change. I think this would apply equally as well to changes due to oil type and or viscosity.

For a given system, gauge pressure, hydrostatic bearing pressure and flow rate are all linked. If you increase flow using pump gears for example, you can be assured with no other changes that all quantities will increase.

Fluid lubrication[edit]

See also: Fluid bearing​

Fluid lubrication results in a full-film or a boundary condition lubrication mode. A properly designed bearing system reduces friction by eliminating surface-to-surface contact between the journal and bearing through fluid dynamic effects.
Fluid bearings can be hydrostatically or hydrodynamically lubricated. Hydrostatically lubricated bearings are lubricated by an external pump which always keeps a static amount of pressure. In a hydrodynamic bearing the pressure in the oil film is maintained by the rotation of the journal. Hydrostatic bearings enter a hydrodynamic state when the journal is rotating.[SUP][11][/SUP]Hydrostatic bearings usually use oil, while hydrodynamic bearings can use oil or grease, however bearings can be designed to use whatever fluid is available, and several pump designs use the pumped fluid as a lubricant.[SUP][citation needed][/SUP]

 

[tkent02]

Or just put Rotella in the engine and ride it forever, or until you blow some bearing or something and put the 1100 engine in...

It's all good.

 

[Steve]

Pos, what I was trying to say was that putting in thicker (higher viscosity number) oil to increase the number on the pressure gauge would not do anything to improve lubrication. On the other hand, the thicker oil will not flow as easily, which might DEcrease lubrication.

Sorry if the drastic alteration of the system confused you, I was just trying to point out how pointless an absolute pressure reading can be, in some situations.

.

 

[posplayr]

Pos, what I was trying to say was that putting in thicker (higher viscosity number) oil to increase the number on the pressure gauge would not do anything to improve lubrication. On the other hand, the thicker oil will not flow as easily, which might DEcrease lubrication.

Sorry if the drastic alteration of the system confused you, I was just trying to point out how pointless an absolute pressure reading can be, in some situations.

.

I got that point, but I think the exact opposite is the case. Gauge pressure is monotonically increasing with increasing bearing pressure under a increase in viscosity. In other words if you put thicker oil into the engine, and the gauge pressure goes up, then there is more pressure at the bearing.From your analysis it may seem counterintuitive, as the the resistance of the system to flow is higher with higher viscosity which would make one think that the bearing pressure is lower. However, from the electrical analogy if gauge pressure is higher than bearing pressure also has to be higher. The explanation must be that the pump generates more pressure as it has less pressure loss from high viscosity.

The fundamental point is that just like a voltmeter would measure potential reflecting voltage all around your electrical system (regardless of the losses downstream), the gauge pressure is the equivalent and when it goes up all other pressures have to go up as well.

 

[Fjbj40]

The pressure is actually built by the clearance between the rotating assemblies and the bearings. True the pump provides pressure, but really it is flow. To tight a clearance and you will have a higher pressure and lack of lubrication. To large a clearance and you will have a lower pressure, then the oil film will be too large and knock knock, not good.

Volume of oil passages are also part of the formula, but they have nothing to do with building the pressure in the engine. The passages ensure an adequate volume for lubrication, as part of the overall system design.

The manufacturer provides the specific clearances between the rotating assemblies, maintain those and provide a larger VOLUME pump and all will be good, engine will be happy and last long time.

 

[posplayr]

The pressure is actually built by the clearance between the rotating assemblies and the bearings. True the pump provides pressure, but really it is flow. To tight a clearance and you will have a higher pressure and lack of lubrication. To large a clearance and you will have a lower pressure, then the oil film will be too large and knock knock, not good.

Volume of oil passages are also part of the formula, but they have nothing to do with building the pressure in the engine. The passages ensure an adequate volume for lubrication, as part of the overall system design.

The manufacturer provides the specific clearances between the rotating assemblies, maintain those and provide a larger VOLUME pump and all will be good, engine will be happy and last long time.

I do not disagree with any of that ; you have can't get any pressure at the bearings if there is to much resistance restricting the flow. The question really is , "If I change my oil and the pressure increases or equally as well when my oil is cold and the pressure is high, do I have more lubrication as when the pressure was lower? In this context lubrication is "hydrostatic pressure" at the bearing.

The answer is, for a given engine, the pressure at the bearing will always be higher if the gauge pressure is higher. We are not designing an engine, only trying to determine what is happening when there is a viscosity change.

 

[Guest]

Hey gs650mann. Where in East TN are you?

Me and my son both have an 82 750E. Really fun bike. We've had them like 3 years now and no issues. Follow what others have said and go with the Rotella oil. I have somewhere on my computer saved the oil pressure mod. Just a matter of adding some more washers but you have to drop the oil pan. I plan on doing mine this upcoming winter since I'm rotating riding this bike with another one I have. You should be fine with this bike and maybe see about doing the mod, either now or in the future some time.

Enjoy riding it. And yes, that guy at bike night didn't know what he was talking about.

 

[posplayr]

http://turbo-lab.tamu.edu/proc/turboproc/T1/T1pg39-55.pdf


It is turning out that this topic of oil viscosity v.s. pressure is too complicated to come up with a simple set of conclusion. It is clear that pressure is not the only determinant, and that when switching to a multi grade oil, you can have a pressure drop that is beneficial. That benefit is probably due primarily to increase flow. However to suggest that lubrication is wholly to do with flow and not pressure is a bit of an overstatement as initiated Abramovitz paper.
The statement is describing what happens at the bearing not at at the other parts of the system that must be designed to make sure that the appropriate pressure and flow ranges are attained.

This is a balancing act that much be balanced and I would recommend doing what other people have done that is know to work. If nothing else follow the manufacturer's recommendation


https://books.google.com/books?id=Z...il pressure change with oil viscosity&f=false

Pretty good overview of the basics; don't stray to far from the manufactures recommendations

http://www.motorcyclecruiser.com/tips-tech/beginners-guide-to-oil-how-it-works

 

[GSXR7ED]

16V Engine Flaw

16V Engine Flaw

Hmmmm, I remember during my oil pan removal/replacement it was recommended I do a fix (I'm guessing this pressure fix). I didn't do the fix.

I didn't push my bike too hard but I did however make long trips from Alamogordo to Las Cruses/Roswell hitting 6K+ RPMs for several miles and my "T" handled it well. I have to R2 the valve cover gasket, cam-chain tensioner, and fork seals but other than that...all was well with my bike.

Lots of good info here about the 16v engine with flawed design.

Ed

 

[Crank]

And here I thought one of the only good things on my bike was the roller bearing crank

If you could see the state of the 750 I was given you would understand.