Results 1 to 4 of 4
  1. #1

    720 Stock head compression 150?

    Hey guys I dont normally post over here more on into stand ups but would like to clarify that a good 720 motor has at least 150 psi per cylinder with less than a 10% variance between cylinders.

    also would a ski with 135 per hole be needing a rebuild soon?

  2. #2
    mibunkerking's Avatar
    Join Date
    Aug 2008
    on the 720, yes you are correct.

    the 135 would depend on what motor. a 951 thats about normal. for the smaller motors, as long as its above 110 and (the most important thing) within 10%, it should be ok.

  3. #3
    bsdbum's Avatar
    Join Date
    Feb 2009
    Orlando, FL
    Ive seen SBT 657x motors come new with that low of compressing rebuilt. So I assume when they bore them you might loose a little comp.

  4. #4
    KrunchovXPL-GTX-RX's Avatar
    Join Date
    Mar 2009
    Aiken, SC
    A stock 717 is more like 140 so 135 is fine. There are too many variations in battery strength, guages, and location to worry too much over 5 or even 15 psi versus what you read on the boards.

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. gp800 compression with stock head
    By goose in forum Yamaha PWC Performance (2-stroke)
    Replies: 2
    Last Post: 03-06-2008, 09:30 PM
  2. What is Head Torque for a 150 PSI GPR Head?
    By LS2000 Cop in forum Yamaha PWC Performance (2-stroke)
    Replies: 3
    Last Post: 10-19-2007, 11:28 PM
  3. riva head only 135 compression
    By MB VIP in forum Yamaha PWC Performance (2-stroke)
    Replies: 2
    Last Post: 08-12-2007, 12:30 AM
  4. need 150-155 p.s.i on stock head
    By Hydrotherapy in forum Yamaha PWC Performance (2-stroke)
    Replies: 14
    Last Post: 11-19-2006, 06:11 PM
  5. head compression, keyway..?
    By titi0314 in forum Yamaha PWC Performance (2-stroke)
    Replies: 9
    Last Post: 04-06-2006, 10:12 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