Results 1 to 4 of 4

Thread: Piston question

  1. #1

    Piston question

    Does anyone know if a 2003 185hp supercharged piston will fit the 2002 4tec non supercharged engine (155hp) Dont know if everything is the same but possible one might be forged or something?

    Thanks,
    Jesse


  2. #2
    Mothman's Avatar
    Join Date
    May 2011
    Location
    West Texas
    Posts
    2,999
    +1
    1,479
    It will fit, but the compression numbers are different.
    If I remember correctly, the NA skis have much higher compression than their SC brethren.
    The 185's are also cast, but the 215's and up are forged!
    I'd go with an oem 155 piston to make sure.
    Good luck!

  3. #3
    A local shop seemed to think they would work, but wanted a second opinion. Not sure why the compression would change?

  4. #4
    Mothman's Avatar
    Join Date
    May 2011
    Location
    West Texas
    Posts
    2,999
    +1
    1,479
    By adding a tiny bit of material to the top of the piston, the amount of space between it and the head (during compression stroke) is lessened, in turn, increasing compression since there is less space to cram the fuel/air mixture.
    On the other hand, remove a tiny bit of material, and the amount of space is enlarged, decreasing the amount of space to cram the fuel/air mixture, ie decreasing compression.
    Also, the edge of the piston clearance with the head is the major contributor. Too close, the rod can stretch, and the piston contacts the head-boom.
    The 1503 4-tec cylinder bore is the same for both, so yes, the piston will fit, but it may give the wrong compression.
    If you use a lower compression piston for one cylinder, it will run, but it won't run as well as it should. One cylinder won't produce as much power as the others.

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Dumb piston question
    By xplayer2885 in forum Polaris Open Discussion
    Replies: 2
    Last Post: 08-27-2008, 10:49 PM
  2. Two part piston question
    By iam026tb4u in forum Yamaha Open Discussion
    Replies: 3
    Last Post: 10-16-2007, 09:09 PM
  3. Piston Questions
    By SpeedJunky in forum Yamaha Open Discussion
    Replies: 8
    Last Post: 01-20-2007, 03:58 PM
  4. Piston question 65U
    By OsideBill in forum Yamaha PWC Performance (2-stroke)
    Replies: 2
    Last Post: 05-25-2006, 12:57 AM
  5. Pro X Piston question
    By spdracr in forum Yamaha PWC Performance (2-stroke)
    Replies: 7
    Last Post: 09-18-2005, 04:23 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
  •