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  1. #1

    Issue with rebuilt msx150

    Finally got around to the second rebuild on this msx150 motor. Has the following done
    New cyliner head. Sleeves fitted to bores. New pistons and rings. Valves shimmed correctly.
    All back together and installed.
    Fresh motor has 154psi on both cylinders.
    Cyinder leakage tested at less than 10% on both cylinders.

    Fittted a new aftermarket turbo cartridge.
    Ski has stage 2 precision ecu and skat track impeller.


    First test run today and it ran well but had the following issue.
    Max rpm is achieved at approx 70% throttle @7150 rpm. At full throttle rpm is still 7150.
    If i back the throttle back lityle at a time the rpm rises to 7300.

    I also rechecked the compression after 2 hours running and both cylinders had dropped to 135 and 141psi.
    Anyone have insight as to why i am getting max rpm at 70% throttle.
    This this has more work done to it and has never as good.


  2. #2
    ripcuda's Avatar
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    Hey steelroe... glad to hear you're back on the water.

    Did you do the eThrottle ECU relearn procedure to remap the ETB sweep? I could see that affecting throttle sweep

    How did you break-in the engine? Might the 154psi have been "wet"... oily cylinders... and later the 135/141psi was on normal "dry" cylinders?

    What speeds are you seeing?

    My stock ECU will peak somewhere between 7400-7500... momentarily... depending on how I got on it, chop, etc. But it usually settles down to a 7200-7300 sustained WOT rpm.

    I know the Precision ECU removed the soft rev limit and upped the hard rev limiter.

    Cheers!

  3. #3
    Hi Ripcuda,
    Cheers for the reply. Yes I finally got it going, too busy building ski's for other people and put my own on the back burner.
    This one has been a bit of a nightmare with headgasket leakage. Think we finally cracked that issue.
    In relationto the ETB procedure, is this done as per the manaul.
    Lanyard in for 30 seconds then remove.
    Leave for 2 minutes then start the engine.

    My first compression check was after running the motor for approx 10minutes on the hose. BOth at 154psi. I would have though that oil would have burned off after that lenth of time. I am a little worried that the WOT runs I did yesterday may have done some damage!!!! I would have thogh that both cylinders would be exactly the same after rebuil (Wet or DRY)
    At WOT I am seeing 60mph max on gps.
    Will cold test compression again today.

  4. #4
    hill160881's Avatar
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    I am seeing the same commonality with these webber engines again and again as I read. It seems like a poorly designed and poorly made lower end causes no end of pain when rebuilding these things. The cylinders are free standing and unsupported, the aluminum used is soft and the consistency or variation between blocks is HUGE and would make a machinist cry.

    Something else that i want to know is did the machine shop use a distortion plate or some other method of distortion prevention on the head surface and lower end when boring and sleeving? If not 1 in 5 cylinder jobs will fail quickly as distortion can be as much as .003 when you torque the head down.


    If I designed the sleeves I would have supported the upper part of the cylinder at the same time. But hindsight is always 20/20

    Still love this engine though

  5. #5
    ripcuda's Avatar
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    Yeah... Hill has some good points. Both Steelroe and I have sleeves in our blocks... but I don't think they were installed/final-bored using any sort of torque plate to simulate a torqued down head. Wonder if it's just a first generation block issues on the MSX... They've seemed to have them sorted out and working well on the later gen Polaris FST sleds.

    Not sure why your compression would change that much. I'm assuming it's not the gauge. I'm sure your using top octane "premium" fuel. Randy stresses that alot... about the detonation potential and having good fuel. If your compression stays at 135/141... I wouldn't fret too much... that's still very good and the upper range of spec.

    The ETB relearn is a quick throttle sweep procedure to relearn the ECU.
    - lanyard in
    - tap starter (don't start)
    - slowly squeeze throttle to WOT (should hear clicks and hums of ETB moving)
    - hold 2 seconds
    - slowly release throttle to none
    - pause 2 seconds
    - repeat x2
    - pull lanyard... wait a few minutes

    This needs done whenever you swap ECUs, I know. I needed to do this on a batch of MSX110 ECUs I tested for Randy... when I didn't do it, it would not throttle right... sometimes only throttle up half way then have issues. When I did it... everything was fine. Food for thought.

    Cheers!

  6. #6
    So I checked compression this morning on cold engine.
    Numbers were 140 and 155.
    So i rechecked the valve shim clearance. Found some valves a little tigh eventhough i triple checked them after rebuild and set to the upper limits.
    After adjusting i rechecked and numbers were 145 155.
    I also replaced the bov as it was leaking at idle.



    Back on the water today and rpm was good at 7350-7400.
    Boost pressure was @16psi
    Speed topped out at 61mph

    However once home i rechecked the compression and the numbers had dropped to 130 140.
    Also the plugs looked grey in colour.
    What the hell is happening here. Maybe I have pushed it to much too soon without proper break in.
    The turbo cartridge I am using is from a 1.8T Audi. The part number was posted on here some time back. Turbine wheel is identical to standard MSX turbo, the compressor wheel is slightly larger diameter at the bottom of wheel.
    I am wondering it the turbo is at fault, building pressure too fast, or too much flow leaning the engine out. I am not a turbo guy so have no idea as to how it may effect thing.
    However at wot the pressure issteady at 16 psi
    Coolant level is staying at the correct level.

    After one particular WOT run this evening I shut the engine down for approx 30 seconds. When I restarted it the engine overheat light was on. I checked the coolant and it was not very hot (sensor is new). I stopped the engine and restarted and light was out. I put it down to maybe heat soak after the WOT run.
    Last edited by steelroe; 06-15-2014 at 04:59 PM.

  7. #7
    hill160881's Avatar
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    My msx did 59.9 mph @ 7400 rpm GPS stock. So something is up for sure. You cant be getting to much air and running lean. The computer would know its getting more air and add fuel unless the O2 sensor is bad. But then that would kick an engine code I would think.

    Is it smooth from a dig, Other than the limiter? No slow surging in the upper rpm bands? A 4-6 hour break in at 4500 rpm with occasional wot runs for 30 sec is a good break in. I would go 10 hours.

    What does the oil look like? It should be clean as hell still.

    Open the coolant resevor. Any foam or water oil residoo? Use your finger to wipe inside and check.


    Never shut this engine or any turboed engine down after a wot run. It needs time to cool down!!!!! Thrust bearing turbos can freeze up and i think the k03 is. While I may not be an expert in this engine I am pretty good at the 4 cylinder turbo stuff Its the same as this in every way.
    Last edited by hill160881; 06-15-2014 at 05:30 PM.

  8. #8
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    What are you running for fuel? I think 91 octane is a minimum on these motors, with even a little more octane being better.

  9. #9
    hill160881's Avatar
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    The reason the temp light went off upon restart was the water in the tail pipe of the turbo had no time to cool off before shut down and registered as over heat when it came back online.

    Is this the old O2 sensor? Never reuse these as they almost always get oil contaminated during the build.

  10. #10
    Temp light is for the coolant temp. The temp switch in the exhaust Mani only limits rpm if activated, it does not have a symbol to display on the gauge.
    O2 sensor is new. From memory does the O2 sensor not become redundant after a certain percentage throttle. I thought i read this in the manual.
    Oil is golden and spotless.
    I did have some oil residue inside the res but this has cleamed up. I beleive it was residual from the last head failure.

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