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  1. #1

    Default 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Hi all, I am interested to understand the purpose of the check Valves (1 per feed line from the engine driven main oil pump).

    A Check Valve can have one out of three different ways of "operating"
    1. The normal way, allows oil to flow in one direction (towards the valve body and in to the crank case) but not in the other direction (when crank case pressure is higher than oil pump deliver pressure and would therfore effect the pressure in other three oil supply lines via the main oil pump outlet manifold)
    2. Failure Mode Nr 1; Stuck Closed
    3. Failure Mode Nr 2; Stuck Open

    The Normal Way and Failure Mode Nr 1 are both quite obvious, but what if it is Stuck Open (as in "3. Failure Mode Nr 2")?

    What would be the effect of a "3. Failure Mode Nr 2" situation?

    My thinking;
    1. Only environmental effect (higher oil consumption) i.e. will smoke more
    2. It will brake down with catastrophic effect

    This is an almost philosophic question, Please keep your answer to the topic, I am not interested of tip like "mix the oil in the fuel tank insted" or "that is a crappy engine"
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by eddievan; 06-04-2020 at 01:50 AM.

  2. #2

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Are you running 1 or 2 motors on your boat. BETO came out with the PBS oil system controlled by rpm and carb stroke and not with those check valves unless you have a sub tank and main tank with 2 motors.
    Last edited by Tegweni; 06-04-2020 at 06:11 AM.

  3. #3

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Quote Originally Posted by Tegweni View Post
    Are you running 1 or 2 motors on your boat.
    Hi, its a one engine installation thanks

  4. #4
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    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    I think the oil goes into the intake manifold.----So crankcase pressure is not involved here.---I do not see a BETO listed for 1998 model 115 HP
    Last edited by racerone; 06-04-2020 at 06:42 AM.

  5. #5

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Quote Originally Posted by racerone View Post
    I think the oil goes into the intake manifold.----So crankcase pressure is not involved here.---I do not see a BETO listed for 1998 model 115 HP
    Did you notice that it is a 2-stroke engine that I ask this question about?
    All fuel/Air/Oil mixture passes the crank case before it enters the combustion champer, it is the pressure in the crank case that pushes the fuel/Air/Oil mixture in to the combustion chamber.

  6. #6

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Quote Originally Posted by Tegweni View Post
    Are you running 1 or 2 motors on your boat. BETO came out with the PBS oil system controlled by rpm and carb stroke and not with those check valves unless you have a sub tank and main tank with 2 motors.
    I believe you might be incorrect regarding this, my friend who also have a single engine installation (same model) and his engine do also have these check valves.
    And they are in my Service Manual as well.

    Why would you remove them as soon as you have a 2-engine installation?

    And I do have the 10 liter sub-tank, but I do not understand why that should have something to do with the oil supply in to the engine? For me that is two complete different systems that the only commin thing they have is the oil. One is a Engine Oil Pressure System and and the other is a Oil Transfer System
    Last edited by eddievan; 06-04-2020 at 03:03 PM.

  7. #7
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    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    edited

  8. #8

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    There are 2 ways the PBS system gets fuel into the motor 1st way is the oil pump pumps oil to the fuel pump then it mixes and enter the reed vales then into crank case .The other way the oil pump pumps oil into ports after the carb throttle plates before the oil/air /fuel mix enters the crank case through the reed valves you have this system that is why you have the check valve in place so that pressure from the piston when it comes down it will not put pressure through the reed vales back down the oil line the check valve stops it .

  9. #9
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    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    I thought oil was injected BEFORE the reed valves.-----So these check valves do not see crankcase compression.

  10. #10

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    The mixture takes place before the reed valves there will be some pressure from the pistons when they go up and down it will come through the reed valves the check valves prevent the pressure going into the oil lines . i may be wrong but this is how it works.

  11. #11
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    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    There won't be any pressure from pistons between the carburetors and reed valves !!-----Crankcase compression happen INSIDE the crankcase.

  12. #12

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Quote Originally Posted by racerone View Post
    There won't be any pressure from pistons between the carburetors and reed valves !!-----Crankcase compression happen INSIDE the crankcase.
    When the piston comes down is what the designers took into consideration with this system of feeding oil into the inlet manifold and oil air and fuel mix after the carb throttle plate and before the reed valves, you cannot have any opposing pressure in the system and that's why they put check valves in

  13. #13

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Hi and thanks for your replies, here are a couple of pictures that can bring some light to this topic.
    Please remember that my question is "what effect will I notice if all 4 check valves are stuck in the open position".

    The picture below shows the rear sides of the Throttle Valve Assy to the right and the Reed Valve Assy (with the reed valves in gold) on the left.
    The direction of flow for the air, air/fuel and air/fuel/oil mixtures respectively is from right to left and it is the rectangular Air Inlet Ports you see in the most far right.
    Click image for larger version. 

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    Below is the forward side of the Reed Valve Assy
    Click image for larger version. 

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    Below is the installation on the actual engine
    Click image for larger version. 

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    Last edited by eddievan; 06-04-2020 at 11:46 PM.

  14. #14

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Quote Originally Posted by Tegweni View Post
    When the piston comes down is what the designers took into consideration with this system of feeding oil into the inlet manifold and oil air and fuel mix after the carb throttle plate and before the reed valves, you cannot have any opposing pressure in the system and that's why they put check valves in
    Can it be so that the reason for the four small oil check valves is to block for the pressure build up that the they are exposed to before the reed valves closes fully, the flow that goes reverse into the oil hoses due to the "slow reaction time" of the reed valve?

    I mean, how large of a pressure are the hoses and check valves designed for to withstand, the hose and clamps are just slid on?

  15. #15

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Quote Originally Posted by racerone View Post
    I think the oil goes into the intake manifold.----So crankcase pressure is not involved here.---I do not see a BETO listed for 1998 model 115 HP
    Hi, here is a picture of my Engine ID Plate, I have it in Europe so maybe you dont have this model in the US
    Click image for larger version. 

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  16. #16

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    They should open at +/- 11 psi what concerns me is that the 1984 beto never came out with those check valves there again it may be that the PBS design was the 1st design.

  17. #17

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Quote Originally Posted by racerone View Post
    There won't be any pressure from pistons between the carburetors and reed valves !!-----Crankcase compression happen INSIDE the crankcase.
    Hi and thanks, since the reed valves are "normaly open" there will be a slight time period with reverese flow before they actualy close.
    During this short period the reverse flow will meet the oil flow coming out of the supply line
    This oil flow will have the pressure of the Main Oil Pump and as long as the Main Oil Pressure Pump is higher than the reverse flow, the oil will still be supplied into the area between the throttle valve and the reed valve.

    Maybe it is for this very short period of time the reason for the check valve is installed

    If that would be correct I assume that if the check valve is stuck open, there will be a lower degree of lubrication due to that the oil flow must regain the distance in the hose where it have been "pushed back" by the reverese airflow..

    Hmm it fels as we are getting somewhere here

  18. #18

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Yes and we all learned something today

  19. #19

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Quote Originally Posted by Tegweni View Post
    Yes and we all learned something today
    He he I just wished that there would be more of "us"

  20. #20

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Quote Originally Posted by Tegweni View Post
    They should open at +/- 11 psi what concerns me is that the 1984 beto never came out with those check valves there again it may be that the PBS design was the 1st design.
    11 plus or minus of what (main pressure)?

    The thing is that when I removed the 4 check valves one was "broken" (the body has separated but undamaged, I could assembly it again but not installing it though)

    One part of the body was fully unblocket (you could see right through it), the other part (that was blocked for air when I tried to blow or suck air through it), then I tried to pull a steel wire trough it, to try to unblock it, it felt as it was a construction inside it blocking the passage of the steel wire, that makes me think that it also has an "opening pressure" to allow oil in the direction of the arrow, I dont know, strange it is
    Last edited by eddievan; 06-05-2020 at 12:50 AM.

  21. #21

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    11 psi from the pump.

  22. #22

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Quote Originally Posted by Tegweni View Post
    11 psi from the pump.
    Aha, okay so it opens for supply from 0-22 psi
    Then all my check valves are faulty because I cant even open them by blowing in to them, nor suction by mouth.

    Actually I have 4 ea BETO egngines and ALL 16 Check Valves are the same, I can not make any flow either way, can all be be faulty, "the story of my life"

  23. #23

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    I belive I have figured out the purpose, except from "they are there for a resaon"

    When I cranked teh motor with the spark plugs removed and oil pump arm disengaged and the arm in "FULL FLOW" position, the "flow" of oil that came out was so low that it seemed to transpirate their way out.

    So if the oil gets pushed back at shut down the oil will not be prepared at next start, and with that low flow it could take a looong time before it will enter the crank case and cylinder.

    Cheers all and I wish you all a wonderful boating summer

    I know I will www.facebook.com/boatfixing

  24. #24
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    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    These oil line check valve do not see crankcase COMPRESSION at all.---------------How can there be pressure in an open chamber ?-----Carburetors are open , so no + pressure in the intake manifold !!

  25. #25

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Quote Originally Posted by racerone View Post
    These oil line check valve do not see crankcase COMPRESSION at all.---------------How can there be pressure in an open chamber ?-----Carburetors are open , so no + pressure in the intake manifold !!
    The reed valves closes due to the main mixture of air and fuel stalls and an reverse flow appears (I understand you talk about the intake manifold and that is before the rees valves).

    My conclusion is that the function for the check valves comes in to roll when stopping the engine (throttle valves fully closed, and reed valves closes slower than when it run) and the prio is to not push the oil back into the lines with that air coming back, this because that the normal supply flow of the oil is sooo very small/slow, so there could be a risk that it takes a prolonged time for the oil to start lubricate every time you start the engine...

    I dont know, I guess

    I have teached jet engine constructions and believe me, you can have very different pressures in an "open" system

  26. #26
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    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Good luck with your diagnosis of these check valves.-----When does a reed valve start " closing " during piston travel ?----How many millisecond for a reed to go from fully open to closed ?
    Last edited by racerone; 06-05-2020 at 12:37 PM.

  27. #27

    Default Re: 1998 YAMAH 115 HP BETO 2-Stroker Lubrication System Check Valves

    Quote Originally Posted by eddievan View Post
    I belive I have figured out the purpose, except from "they are there for a resaon"

    When I cranked teh motor with the spark plugs removed and oil pump arm disengaged and the arm in "FULL FLOW" position, the "flow" of oil that came out was so low that it seemed to transpirate their way out.

    So if the oil gets pushed back at shut down the oil will not be prepared at next start, and with that low flow it could take a looong time before it will enter the crank case and cylinder.

    Cheers all and I wish you all a wonderful boating summer

    I know I will www.facebook.com/boatfixing
    Run the motor on a premix tank and increase the rpm and check again

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