Results 1 to 4 of 4
  1. #1
    PWD Filoo's Avatar
    Join Date
    Jun 2007
    Location
    Charleston, SC
    Posts
    32

    Stable engine speed.. How stable?

    What's a reasonable amount of + and - rpms when the engine (150 Speedster SCIC 2007) is running at slow speed?

    Everything runs smoothly above 4,000 rpm. But when I idle along, say around 2,760 rpm, it actually tends to flutter randomly between 2,700 and 2,820 rpm. You can also tell that it's not a steady sound, you can hear it revving up & down...

    I've only noticed fluctuations of up to +/- 60 rpm, is this normal? I expected 4 strokes to have a more regular rotation speed...

    PS: the water is not choppy but pretty glassy without currents, so that's not the reason. Is there a way to fine tune the idle setting to a more stable regular speed?
    PS2: Could be the propulsion rather than the engine, but I have not tried running it out of the water at those rpms to rule out a problem with the impeller. Is it safe to do?
    Last edited by Filoo; 07-26-2007 at 07:01 PM.


  2. #2

    Join Date
    May 2007
    Location
    NWFL
    Posts
    42
    Mine does the same thing at lower RPMs (idle up to about 2800 give or take) I just think it is the normal actions of the motor. Not knowing what the torque band is on our motor it could be (I am not an engine guy, so don't quote me) the engine trying to maintain the RPM by constantly adjusting the fuel flow, but not keeping up with itself. Maybe some one with more insight could enlighten us both.

    J

  3. #3
    PWD Filoo's Avatar
    Join Date
    Jun 2007
    Location
    Charleston, SC
    Posts
    32
    I wonder if this only happens with jetboats or also with skis...

    Anyone?

  4. #4
    King_Of_Fun's Avatar
    Join Date
    Jul 2007
    Location
    Catawba Island, Ohio
    Posts
    2,703
    My 185-hp SC does the same thing. I think it's the ECU changing fuel mixtures/rpms to maintain low emissions levels.

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Lost all my engine bids =( how about this one?
    By rdizz81 in forum Polaris Open Discussion
    Replies: 7
    Last Post: 06-29-2010, 10:10 PM
  2. Engine temperatures, How hot...(cold)
    By Doug78 in forum Yamaha PWC Performance (4-stroke)
    Replies: 3
    Last Post: 06-25-2010, 06:59 PM
  3. Engine damage. How bad? (images attached)
    By SideFX in forum 2-Stroke Performance
    Replies: 14
    Last Post: 05-31-2010, 01:13 PM
  4. Towing speed...how fast?
    By iam026tb4u in forum Yamaha PWC Performance (2-stroke)
    Replies: 2
    Last Post: 08-24-2009, 01:15 PM
  5. Engine Pics: How Did I ever have fun on this?
    By Shibby1485 in forum Sea Doo Open Discussion
    Replies: 5
    Last Post: 05-03-2006, 08:15 AM

Posting Permissions

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