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  1. #1
    Rocky_Road's Avatar
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    Maximum RPM's for a MSX 150???

    On the water Sunday, my '04 MSX 150 was turning 7700 RPM's when full throttle, would limit back to around 7500, then back to 7700. It never stayed at 7700 for any length of time, but I had to use the throttle to maintain the 7450 that I am used to. Can the Weber engine handle the higher rpm's safely? If so, then I am not going to worry about it....

    Did have some screaming runs, though!!!


  2. #2
    Rocky_Road's Avatar
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    bumpity-bump!!!

  3. #3
    desperado's Avatar
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    Quote Originally Posted by Rocky_Road View Post
    On the water Sunday, my '04 MSX 150 was turning 7700 RPM's when full throttle, would limit back to around 7500, then back to 7700. It never stayed at 7700 for any length of time, but I had to use the throttle to maintain the 7450 that I am used to. Can the Weber engine handle the higher rpm's safely? If so, then I am not going to worry about it....

    Did have some screaming runs, though!!!
    The weber MPE750 engine can safely handle wot rpm of around 8,200 in the snowmobile configuration. However, the PWC ECU is a Bosch ME7.4.4 as opposed to a M7.4.4 in the snowmobile version. The ECU difference results from the fact that the PWC configuration is a drive by wire setup as opposed to standard intake venturies for the snow version.

    With the above being said, your PWC ecu controls the throttle opening based on many inputs. It is normal to briefly see higher rpm figures when you press the throttle to the bars.... but the ecu will always pull back the throttle plate to the target 7,500 maximum rpm. Also, please note that above 7,500rpm, the ecu will gradually retard timing and detune the engine.

    Hope this helps.

  4. #4
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by desperado View Post
    The weber MPE750 engine can safely handle wot rpm of around 8,200 in the snowmobile configuration. However, the PWC ECU is a Bosch ME7.4.4 as opposed to a M7.4.4 in the snowmobile version. The ECU difference results from the fact that the PWC configuration is a drive by wire setup as opposed to standard intake venturies for the snow version.

    With the above being said, your PWC ecu controls the throttle opening based on many inputs. It is normal to briefly see higher rpm figures when you press the throttle to the bars.... but the ecu will always pull back the throttle plate to the target 7,500 maximum rpm. Also, please note that above 7,500rpm, the ecu will gradually retard timing and detune the engine.
    Hope this helps.
    Interesting.
    Is the target RPM limit adjustable in the ECU?

    The more I learn about these Weber engines, the more I like them.

  5. #5
    ph2ocraft's Avatar
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    desperado, WELCOME to the Green Hulk Forums!!

    Thanks for the info, good to know.

  6. #6
    desperado's Avatar
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    Quote Originally Posted by ph2ocraft View Post
    desperado, WELCOME to the Green Hulk Forums!!

    Thanks for the info, good to know.
    Thanks for the welcome.... I've been a watcher here for quite some time... great forum.

    I recently bought a MSX110 which I turned into a 150 by replacing the ECU and doing a few other mods. It is running great.

    Here is a funny story... My friend owns a 2003 MSX140 and he has been trying to get me to buy a Polaris PWC for quite a while. Late last summer, I found a good deal on an MSX110 and pulled the trigger on it. So.... we did a few runs together and I was obviously much slower than my friend... and was taking my share of showers from him blowing by me. My plan when I purchased the MSX110 was to turn it into something different. Then... I found a good used MSX150 ECU with the matching blowoff valve... installed it on my MSX110.... then the following weekend, just when my friend was about to overtake me.... I pressed the throttle to the bars.... you should have seen his face.... ... he took a hell of a shower... . That was so cool and funny!

    After the ECU modification, with the stock impeller, my MSX110 went from a 7,100rpm WOT to around 7,700rpm. I even hit the rev limiter at 7,800rpm a few times. The speed difference with the MSX140 is about 1 to 2 mph in favor of the MSX140. Next step: I will change the impeller to take full advantage of the greater torque curve of the Weber engine which is setup to happen at around 7,500rpm.

    I have been playing with these Weber engines for quite some time now. They are great. Last summer, I have made a fun projet converting my Polaris Weber FST snowmobile into a Garrett GT25R turbo platform... If you are curious about the Weber MPE750 engine... then here is the video (with some humour) of my summer project...


  7. #7
    Click avatar for tech links/info, donation request K447's Avatar
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    Quote Originally Posted by desperado View Post
    ...a MSX110 which I turned into a 150 by replacing the ECU and doing a few other mods. It is running great....
    My plan when I purchased the MSX110 was to turn it into something different. Then... I found a good used MSX150 ECU with the matching blowoff valve... installed it on my MSX110....
    After the ECU modification, with the stock impeller, my MSX110 went from a 7,100rpm WOT to around 7,700rpm. I even hit the rev limiter at 7,800rpm a few times. The speed difference with the MSX140 is about 1 to 2 mph in favor of the MSX140. Next step: I will change the impeller to take full advantage of the greater torque curve of the Weber engine which is setup to happen at around 7,500rpm...
    Is that the important difference between MSX1110 and MSX150, just the ECU and turbo blow-off? Hmmm...

    I was wondering, since so many of the parts are the same on both motors...

  8. #8
    desperado's Avatar
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    Quote Originally Posted by K447 View Post
    Is that the important difference between MSX1110 and MSX150, just the ECU and turbo blow-off? Hmmm...

    I was wondering, since so many of the parts are the same on both motors...
    Engine internals are the same. Differentiators are: 1-) ECU, 2-) Blowoff valve, 3-) pump Impeller and 4-) larger intercooler on the MSX150.

  9. #9
    Moderator beerdart's Avatar
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    desperado Great work on the sled you evil genius. Do you have any numbers on the combination? I think we found you a avatar.

  10. #10
    Rocky_Road's Avatar
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    Quote Originally Posted by desperado View Post
    The weber MPE750 engine can safely handle wot rpm of around 8,200 in the snowmobile configuration. However, the PWC ECU is a Bosch ME7.4.4 as opposed to a M7.4.4 in the snowmobile version. The ECU difference results from the fact that the PWC configuration is a drive by wire setup as opposed to standard intake venturies for the snow version.

    With the above being said, your PWC ecu controls the throttle opening based on many inputs. It is normal to briefly see higher rpm figures when you press the throttle to the bars.... but the ecu will always pull back the throttle plate to the target 7,500 maximum rpm. Also, please note that above 7,500rpm, the ecu will gradually retard timing and detune the engine.

    Hope this helps.
    Just what I needed!!!

    My concern arose from my WOT always being in the 7500 range...seeing 7700, out of the clear blue, had me scratching my head! I recently changed the valve connected to the waste gate bellows, and noticed that the hose routed from the front of the engine was slightly expanded (mushroomed) on the end that went to the valve. Since I also discovered that my wastgate door was 'froze' in the full boost position, I assumed that the build up of pressure expanded the hose. Is it possible that this hose is still expanding and allowing for a momentary increase of boost, until the valve 'catches' up? Just curious...since you have reassured me that my Weber can handle this, and more!!!

    What are your thoughts on having the valve lash checked at 100 hours, as the manual demands....

    Love my MSX 150...it is truely a 'gas and go' fun machine!

    Thanks, again!

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