Page 1 of 2 1 2 LastLast
Results 1 to 10 of 11
  1. #1

    GP1200R Compression....

    Hi guys, sold my GP800R an looking at 1200's.
    What is the recommended compression specs for an engine with approx 35hrs since rebuild?
    I tested one today, still STD, has 76hrs but was rebuilt by North Coast Motorsport at approx 40hrs, not sure why that soon but nyways. Crank replaced with hotrod crank all new brgs an gsks, WSM piston kits etc.
    I done a comp test when I viewed the ski with 112psi approx on all pots.
    Is that ok or should I be hesitant?
    My 800r was 130psi on both....

    cheers


  2. #2
    BoostCrzy's Avatar
    Join Date
    Apr 2008
    Location
    Wellington, FL
    Posts
    430
    +1
    1
    depends on your gauge...but if it was even across all three thats fine for stock....

  3. #3
    Thx BoostCrzy.... Yeah it's a new guage so it should be pretty close.
    Just wasn't quite sure, especially cause it had the rebuild so early. It ran fine but will check a few others out yet.

    Got a Riva rideplate an R&D grate in the garage already and will seal the shoe up and fit the plate an grate, then later a Solas prop. Just those few extra should make a noticable difference yeah..?
    Cheers again

  4. #4
    BoostCrzy's Avatar
    Join Date
    Apr 2008
    Location
    Wellington, FL
    Posts
    430
    +1
    1
    yea the intake grate and a rideplate will be best bang for your buck....then get the carbs rejetted..cut the head....and put prop in her...then your golden...

    -Jack

  5. #5
    32 Valves To Love! Racecar_Dave's Avatar
    Join Date
    Jul 2009
    Location
    Alum Creek
    Posts
    635
    +1
    2
    get a 1300r

  6. #6
    Sweet. Will do. Do u have to change the hsg when u do the om prop?

    Well I've been looking at the 1300's also lol, it always seems that when u are at your spending budget an u see the next bigger thing ie 1300 for jusssst that wee bit more, u think meh what's another coupla grand haha...

    Thx heaps again for the support guys

  7. #7
    if your not using a snap on tool. add 10 psi at least for using a screw on compression tool

  8. #8
    Moderator DrewNJ's Avatar
    Join Date
    Dec 2005
    Location
    Marlton, NJ
    Posts
    3,716
    +1
    1
    Quote Originally Posted by djpeetur View Post
    if your not using a snap on tool. add 10 psi at least for using a screw on compression tool
    Would you care to elaborate on this comment and why someone should add 10 psi to their numbers JUST because of a brand name difference in tools? First time I've EVER heard that because it's a snap on gauge it's going to measure "at least" 10psi higher than any other gauge set.


    GPRocket, 112psi is very normal for compression on the 1200 motor. The range is around 110-115 for a stock motor depending on a lot of variables. Like Jack said, it's most important for them to be fairly even across all 3.
    I've gotten to the point where I don't pay a whole lot of attention into the specific compression number as long as they are fairly even. You can see a difference of 5-10psi on the same cylinder depending on temps, method of checking, motor temp, when the last time the ski was ran, oil in the cylinders etc etc etc etc......
    Personally, I start to worry when I see a difference of about 10% between the 3 and usually when there is problem it's pretty obvious.... like 112-70-115

    Good luck with the new ski.

  9. #9
    All hail the Chief! fullboogie's Avatar
    Join Date
    Nov 2005
    Location
    Texas
    Posts
    3,155
    +1
    44
    Quote Originally Posted by Racecar_Dave View Post
    get a 1300r
    Real thoughtful response

  10. #10
    Cheers boys... I ended up picking up a pretty immaculate 02 1200 with 71hrs. Comp was spot 120 on all three so i pretty much jumped at it. Although when i looked at the ski an done the test also for myself i noticed they had BR8ES plugs an so changed to the recommended plug & now runs like a clock
    Have sealed the pump shoe up & done the plate & grate to start it off...
    thx

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. Question regarding GP1200R Compressions 65,0,60
    By kdaily in forum Yamaha PWC Performance (2-stroke)
    Replies: 2
    Last Post: 01-17-2014, 08:42 AM
  2. What should GP1200r compression be?
    By AquaGuy in forum Yamaha PWC Performance (2-stroke)
    Replies: 12
    Last Post: 05-11-2011, 05:17 PM
  3. 2002 GP1200R Compression and Break in Questions
    By iam026tb4u in forum Yamaha PWC Performance (2-stroke)
    Replies: 7
    Last Post: 08-03-2009, 09:05 PM
  4. ADA head GP1200R lower compression than expected?
    By chris1200 in forum Yamaha PWC Performance (2-stroke)
    Replies: 9
    Last Post: 06-03-2009, 12:26 AM
  5. GP1200R Compression
    By angelico in forum Yamaha How To & FAQs
    Replies: 6
    Last Post: 07-25-2007, 02:33 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
  •