Page 1 of 2 1 2 LastLast
Results 1 to 10 of 15
  1. #1

    Join Date
    Mar 2011
    Location
    New Zealand
    Posts
    130

    951 Magneto timing ????

    I've just changed the flywheel on my 98 951 motor for a new one.

    I went to fit the magneto to the new flywheel and noticed with all the (original) bolts in place the magneto had quite a lot of movement. i.e the holes in the magneto are bigger than the bolts

    The raised bit on the magneto controls the timing so i thought the magneto would have some locating pins or something ?

    Anyway i choses a mid position for the magneto and tightened the bolts. Problem is now the ski is pulling less rpms - maybe about 100-200 so i presume i have to change the position of the magneto to get the timing where it used to be.

    Question is - which way - do i advance it or retard it ? Don't really want to do it twice if i can help it.

    Thanks for any suggestions

    Phil


  2. #2
    flyin' the friendly skies airbornexp's Avatar
    Join Date
    Aug 2007
    Location
    Mahomet, Il. USA
    Posts
    6,004
    +1
    163
    set the front piston to TDC then on the mag cup position it just before the pick up...that is the correct position

  3. #3

    Join Date
    Mar 2011
    Location
    New Zealand
    Posts
    130
    Thanks.

    That sounded quite easy till i remembered the pickup is mounted on the cover that gets removed to access the mag cup.

    Is there an alignment mark on the crank cases ?

  4. #4
    SURFnTURF's Avatar
    Join Date
    May 2007
    Location
    Australia
    Posts
    878
    +1
    11
    This actually changes the timing by about 3/4 of a degree I always turn it the way the crank is spinning so it advances it. I have added 2 degree advance across through the programmer as well.I run good fuel with enough squish and it still revs into the 7200s.

  5. #5

    Join Date
    Mar 2011
    Location
    New Zealand
    Posts
    130
    Thanks for that - 7200's is impressive - what else have you changed except the timing and what's the squish ? Have you gps ed your speed at 7200 ?

  6. #6

    Join Date
    Mar 2006
    Posts
    1,829
    +1
    119
    rev limiter is set at 7150-- if you run extended on the rev limiter you will be buying a new mpem sooner or later. At 7200+ he has raised the rev limit with either a remap, micro touch, MSD or Advent.

  7. #7
    SURFnTURF's Avatar
    Join Date
    May 2007
    Location
    Australia
    Posts
    878
    +1
    11
    This is a Les Cooke engine that has been bored with an offset to the crank( not perpendicular) the mpem has been re flashed as well with a slightly higher timing curve. Squish is set at 67 thou .I run a 97.5 pipe and have re pitched the prop ,This is a surf jumper with fantastic low/mid punch but will almost run with a stock rxp top end. PTO has been machined down to the coupler diameter size with an aluminium flywheel at the front.Rinnaldi reeds and spacers, OEM carbs, 135 psi and I run good fuel through it. It is a good all round reliable machine that gets me home at the end of the day.

  8. #8
    flyin' the friendly skies airbornexp's Avatar
    Join Date
    Aug 2007
    Location
    Mahomet, Il. USA
    Posts
    6,004
    +1
    163
    Quote Originally Posted by SURFnTURF View Post
    This is a Les Cooke engine that has been bored with an offset to the crank( not perpendicular) the mpem has been re flashed as well with a slightly higher timing curve. Squish is set at 67 thou .I run a 97.5 pipe and have re pitched the prop ,This is a surf jumper with fantastic low/mid punch but will almost run with a stock rxp top end. PTO has been machined down to the coupler diameter size with an aluminium flywheel at the front.Rinnaldi reeds and spacers, OEM carbs, 135 psi and I run good fuel through it. It is a good all round reliable machine that gets me home at the end of the day.
    saweeet!

  9. #9

    Join Date
    Mar 2011
    Location
    New Zealand
    Posts
    130
    All good - just tested ski after turning mag cup in direction of rotation and ski revs to about 7k. Top speed indicated at 53mph think the impellor is bent (just bought another but no arrived yet). Thanks for the advice.

  10. #10
    SURFnTURF's Avatar
    Join Date
    May 2007
    Location
    Australia
    Posts
    878
    +1
    11
    Quote Originally Posted by southernflip View Post
    All good - just tested ski after turning mag cup in direction of rotation and ski revs to about 7k. Top speed indicated at 53mph think the impellor is bent (just bought another but no arrived yet). Thanks for the advice.
    You might need to re pitch your new prop to suit your revs.It is quite easy to do on the bench.

    HERE http://www.greenhulk.net/forums/show...2614-Impeller-
    Pitching-%28Updated%29
    You want that engine to rev into the 6950-7000rpm range

    Chart for bending blades.
    Attached Files Attached Files

Page 1 of 2 1 2 LastLast

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. 951 ignition timing
    By dan9900 in forum Sea Doo Open Discussion
    Replies: 0
    Last Post: 05-20-2013, 12:07 PM
  2. First time Seadoo GSXL 951 project
    By elmatta in forum Sea Doo Build Threads
    Replies: 9
    Last Post: 10-24-2011, 11:49 AM
  3. 951 & 787 Ignition Timing Curve Difference
    By Hollymax in forum Sea Doo Open Discussion
    Replies: 7
    Last Post: 09-09-2010, 01:09 AM
  4. 951 timing advance
    By u887266 in forum Sea Doo Open Discussion
    Replies: 2
    Last Post: 04-09-2009, 01:55 PM
  5. Timing on a 951 motor
    By JonnyRXT in forum 2-Stroke Performance
    Replies: 4
    Last Post: 07-18-2008, 07:58 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
  •