Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 22

Thread: Milling head

  1. #1

    Milling head

    Hey does anyone know how much to take off my head on a gp1200r 66v just want to give it some more punch maybe raise it by 20 psi max all three cyclinders are at 115psi. just dont want to give it to a head shop and take to much off.


  2. #2
    zx11rider's Avatar
    Join Date
    Jun 2009
    Location
    Cape Coral
    Posts
    1,132
    Quote Originally Posted by 66V View Post
    Hey does anyone know how much to take off my head on a gp1200r 66v just want to give it some more punch maybe raise it by 20 psi max all three cyclinders are at 115psi. just dont want to give it to a head shop and take to much off.
    Pm Jims performance he can do it for you he knows just what to do, Ron

  3. #3
    Roughly 0.010" will raise it 10 psi. The head gasket is 2 layers remove one which is just under 0.010, and it will go up approx 10psi. But if you want the best performance send it to Jim.

  4. #4
    yeah im in Austraila so it would take to long to get back to me

  5. #5
    Chris03HD's Avatar
    Join Date
    Sep 2009
    Location
    Jersey Shore
    Posts
    582
    +1
    3
    Quote Originally Posted by bigrob View Post
    The head gasket is 2 layers remove one which is just under 0.010, and it will go up approx 10psi.
    What octane will that require then?

  6. #6
    You can get away with premium fuel, 93 octane for up to 145psi depending on timing.

  7. #7
    i run 98 fuel always and i pulled the gasket out today raised it 10 psi there are three peices to the gasket i put one back in ,All three cyclinders are 100psi now where all 90 psi my gauge maybe out a little. thinking of milling the head still as i want it up around 125psi.

  8. #8
    Chris03HD's Avatar
    Join Date
    Sep 2009
    Location
    Jersey Shore
    Posts
    582
    +1
    3
    You originally said they were all 115psi.

    125ish is stock compression, you should be higher after removing one gasket, not lower.

  9. #9
    You have not mentioned any other mods to your ski. What are you looking to achieve. You will have to keep an eye on your jetting as well as you raise your compression.

  10. #10

    Join Date
    Jul 2005
    Location
    Central North Carolina
    Posts
    3,846
    +1
    527
    You can remove .030 safely and run 1 gasket.When you are testing your compression be sure your battery is full charged, hold the throttle open when spinning engine over, leave the sparkplug in the two cylinders not being tested with all sparkplug wires off plugs of course. If you have not used this method for checking compression you have not got the correct reading. Tommy Jordan

Page 1 of 3 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. Milled head speed and RPM results..
    By Fusion in forum Yamaha PWC Performance (2-stroke)
    Replies: 13
    Last Post: 01-06-2008, 02:40 PM
  2. milled head or Riva?
    By dogger in forum Yamaha PWC Performance (2-stroke)
    Replies: 10
    Last Post: 01-03-2008, 09:37 PM
  3. Milling Head...
    By james k in forum Yamaha PWC Performance (2-stroke)
    Replies: 2
    Last Post: 09-01-2007, 11:13 PM
  4. Jims Milled Head Questions
    By Chrisrokc in forum Yamaha PWC Performance (2-stroke)
    Replies: 4
    Last Post: 08-18-2007, 02:35 AM
  5. Milled head and 89 octane?
    By jfoster in forum Yamaha PWC Performance (2-stroke)
    Replies: 15
    Last Post: 04-07-2007, 11:58 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
  •