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GS850 Oil Pressure system

U

uteman

Forum Mentor
Is there a relief valve in the engine oil pressure system of a GS850 engine?
If so, where is it located?
 
Nope. The roller crank bearing engines don't really run any oil pressure to speak of -- they just sort of pump oil around through wide-open passages and it splashes all over. It's actually an extremely robust system, but it's worrying to people used to plain bearing cranks and 60psi.

It's fairly common for people to install oil pressure gauges on these engines and then panic when the readings are five or six psi. (The solution, of course, is to not install oil pressure gauges on roller bearing engines -- you only add potential leak points and you don't get any useful information.) The pump only has to produce enough pressure to get the oil up to the cylinder head.

In some models, there are a few orifices here and there to direct small amounts of oil where they're needed. For example, in the clutch cover of the later model GS850, there's a carburetor jet in the oil passage feeding the clutch release shaft. I believe the function of this is to ensure that a little bit of oil makes it back there, but not enough to affect clutch action.
 
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bwringer said:
It's fairly common for people to install oil pressure gauges on these engines and then panic when the readings are five or six psi.
Click to expand...

It gets even more interesting when the oil warms up and they only see three to four psi. :-\\\

.
 
bwringer said:
Nope. The roller crank bearing engines don't really run any oil pressure to speak of -- they just sort of pump oil around through wide-open passages and it splashes all over. It's actually an extremely robust system, but it's worrying to people used to plain bearing cranks and 60psi.

It's fairly common for people to install oil pressure gauges on these engines and then panic when the readings are five or six psi. (The solution, of course, is to not install oil pressure gauges on roller bearing engines -- you only add potential leak points and you don't get any useful information.) The pump only has to produce enough pressure to get the oil up to the cylinder head.

In some models, there are a few orifices here and there to direct small amounts of oil where they're needed. For example, in the clutch cover of the later model GS850, there's a carburetor jet in the oil passage feeding the clutch release shaft. I believe the function of this is to ensure that a little bit of oil makes it back there, but not enough to affect clutch action.
Click to expand...

bwringer: Many thanks for responding. I kinda figured that was the issue. The oil pressure switch must operate at an extremely low pressure.
I am one of those guys you mention who are more used to slipper bearings in car systems.
A sad day when I do not learn something so today should be a good one!
 
Yep, the oil pressure switch is more of a "flow" switch. If oil is flowing, it's fine.

The oil pump is pretty much the same as an oil pump found in a high pressure engine, so it moves a good bit of oil. It's just that there's no need to force-feed the crank bearings, so there are no restrictions in the system for the purpose of increasing oil pressure.

Several GS models do use plain bearings, of course. Consult your parts diagram and/or shop manual...
 
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bwringer said:
Yep, the oil pressure switch is more of a "flow" switch. If oil is flowing, it's fine.

The oil pump is pretty much the same as an oil pump found in a high pressure engine, so it moves a good bit of oil. It's just that there's no need to force-feed the crank bearings, so there are no restrictions in the system for the purpose of increasing oil pressure.

Several GS models do use plain bearings, of course -- all the 16 valve models, the GS650, the GS450/500 twins (but the GS400/425 used needle bearings).
Click to expand...
The 1100e has roller bearings, the 750 does not.
 
bwringer said:
Yep, the oil pressure switch is more of a "flow" switch. If oil is flowing, it's fine.

The oil pump is pretty much the same as an oil pump found in a high pressure engine, so it moves a good bit of oil. It's just that there's no need to force-feed the crank bearings, so there are no restrictions in the system for the purpose of increasing oil pressure.

Several GS models do use plain bearings, of course -- all the 16 valve models, the GS650, the GS450/500 twins (but the GS400/425 used needle bearings).
Click to expand...
The GS650E chain drive model uses a roller bearing crank.
 
bobgroger said:
The 1100e has roller bearings, the 750 does not.
Click to expand...

TeamDar said:
The GS650E chain drive model uses a roller bearing crank.
Click to expand...

Good to know -- I've removed the bad or incomplete info from my post.

The overall point is that many GS models used plain bearing cranks and high oil pressure, and many used roller bearing cranks and operate with very little oil pressure. Make sure you know what you're dealing with before getting worried.
 
With all this good information being displayed here, I would like to ask: is there enough pressure to sufficiently supply a cooler?
 
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