Page 1 of 6 1 2 3 ... LastLast
Results 1 to 10 of 58

Thread: FX HO RPM Loss

  1. #1

    Join Date
    Sep 2010
    Location
    Aliso Viejo
    Posts
    951
    +1
    75

    FX HO RPM Loss

    Hey Guys,

    I got a hard one hear scratching my head

    Last ride I noticed I had lost 300-400 RPM. Came home, checked compression, 195,195,195,200 cold, then changed the plugs.. Checked air filter, great condition and checked oil, all good!

    I figured I must have had a slightly fouled plug, went back in the water, same thing... I get close to 9700. No vibration, no ill effect just lost in RPM.....

    I have a feeling this is going to make me go crazy....

    BTW, impeller and all is excellent shape, throttle cable good, gas not old....

    No error message, just lost RPM


  2. #2
    64physhy's Avatar
    Join Date
    Aug 2010
    Location
    Weatherford, TX
    Posts
    1,725
    +1
    168
    Here are a few possibilities:
    Fuel pump/filter (but it would likely run a little rough)
    Vacuum leak
    MAF sensor (would likely cause a code)

  3. #3
    Jarrett's Avatar
    Join Date
    Apr 2005
    Location
    Waxahachie, TX
    Posts
    3,011
    +1
    77
    ...
    Last edited by Jarrett; 08-31-2012 at 11:34 AM.

  4. #4

    Join Date
    Jul 2005
    Location
    Central North Carolina
    Posts
    3,846
    +1
    527
    Quote Originally Posted by Jarrett View Post
    How are you measuring RPM? Stock skis don't do 9700 RPM. Was that a typo for 7900? How many hours? Any mods?
    He has a older FX HO ski which has a 10,000 + rpm motor ( 160 HP and 1052cc ) in it not a sho motor! Tommy Jordan

  5. #5
    Jarrett's Avatar
    Join Date
    Apr 2005
    Location
    Waxahachie, TX
    Posts
    3,011
    +1
    77
    ...
    Last edited by Jarrett; 08-31-2012 at 11:34 AM.

  6. #6

    Join Date
    Sep 2010
    Location
    Aliso Viejo
    Posts
    951
    +1
    75
    Dave,

    I think filter/flow issue at full throttle is a suspect as I can't find any other reason. At idle it doesn't need much fuel so it probably would run OK.
    Quote Originally Posted by 64physhy View Post
    Here are a few possibilities
    Fuel pump/filter (but it would likely run a little rough)
    Vacuum leak
    MAF sensor (would likely cause a code)

  7. #7
    YoYamma's Avatar
    Join Date
    Aug 2006
    Location
    Central Florida
    Posts
    21,551
    +1
    4,770
    Jarrett; yeah they used the MR-1 engine up until 2008 I believe, then switched to the 1.8L.
    Captain sometimes loss of RPM can come from overfilling the oil, also are you running the OEM air filter?
    We had two of those engines; in my experience with the MR-1, that OEM air filter might look perfect, but they can get an invisible oil film on them and rob power. Try running it without the air filter and see what happens. You might want to switch to the Riva power filter.

  8. #8

    Join Date
    Sep 2010
    Location
    Aliso Viejo
    Posts
    951
    +1
    75
    No signs of oil on the filter. I really am careful not overfilling the oil BUT I was thinking about running it without filter just for the heck of it...
    It's driving me nuts... It just sat a week as I ride weekly and wham I am hit with RPM loss. I was sure it was a spark plug but that was not it!

    I am now thinking about taking the injectors off to take a look at the filter...
    Quote Originally Posted by YoYamma View Post
    Jarrett; yeah they used the MR-1 engine up until 2008 I believe, then switched to the 1.8L.
    Captain sometimes loss of RPM can come from overfilling the oil, also are you running the OEM air filter?
    We had two of those engines; in my experience with the MR-1, that OEM air filter might look perfect, but they can get an invisible oil film on them and rob power. Try running it without the air filter and see what happens. You might want to switch to the Riva power filter.

  9. #9
    YoYamma's Avatar
    Join Date
    Aug 2006
    Location
    Central Florida
    Posts
    21,551
    +1
    4,770
    Quote Originally Posted by CaptainReza View Post
    No signs of oil on the filter. I really am careful not overfilling the oil BUT I was thinking about running it without filter just for the heck of it...
    It's driving me nuts... It just sat a week as I ride weekly and wham I am hit with RPM loss. I was sure it was a spark plug but that was not it!

    I am now thinking about taking the injectors off to take a look at the filter...
    I'm telling you dude, you can't see the oil.
    I went thru the same thing on both of our MR-1 engines; actually replaced the OEM air filters and within a few months they were robbing power again. Finally dumped the OEM filters and replaced with Riva velocity stack kits and the power filter; never lost power again.

  10. #10

    Join Date
    Sep 2010
    Location
    Aliso Viejo
    Posts
    951
    +1
    75
    When I rob my hand over the filter, its dry as it can be but sure, I will run it without the filter. It revs over 10K in the hole shot then after I get on the plane, it drops RPM to below 10K.

    My dip stick has never seen oil above half, it's always above L like 25%.

    Do you remember how many RPM you lost, were you around 9700 RPM?
    Quote Originally Posted by YoYamma View Post
    I'm telling you dude, you can't see the oil.
    I went thru the same thing on both of our MR-1 engines; actually replaced the OEM air filters and within a few months they were robbing power again. Finally dumped the OEM filters and replaced with Riva velocity stacks kits and the power filter; never lost power again.

Page 1 of 6 1 2 3 ... LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Fx Ho Rpm Kit
    By yami_rida#26 in forum Yamaha PWC Performance (4-stroke)
    Replies: 5
    Last Post: 08-11-2009, 09:31 PM
  2. RPM Kit for fx ho
    By danny.boy001 in forum Yamaha PWC Performance (4-stroke)
    Replies: 2
    Last Post: 06-07-2008, 06:33 PM
  3. FX HO speeds and rpms
    By Hypertoys in forum Yamaha PWC Performance (4-stroke)
    Replies: 15
    Last Post: 11-20-2007, 03:16 PM
  4. FX HO RIVA RPM Kit Review
    By tbyrne in forum Yamaha PWC Performance (2-stroke)
    Replies: 4
    Last Post: 05-31-2007, 06:26 PM
  5. Fx HO RPM KIT
    By Gj#6 in forum Yamaha PWC Performance (2-stroke)
    Replies: 7
    Last Post: 04-19-2007, 10:27 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •