Results 1 to 6 of 6
  1. #1

    polishing exhaust ports?

    Since I have the head and exhaust off my ski now I've been noticing the exhaust ports in the cylinders are very rough.
    What kind of gains are to be had by gasket matching and polishing the ports? I know this helps 4 strokes (I've done it several times) but 2 strokes often seem to react totaly different than I would expect.
    If there are gains to be had should I only do the exhaust side or should I do the intake side as well? I know some think the rough cast turbulance is good for A/F mixture on the intake side but I dont know.

  2. #2

    Join Date
    Oct 2006
    KY/ Lake Cumberland
    I have never ported a ski, but I used to race mx with atv's. When I would port a 250R cylinder, I would make the exhaust completely smooth. The intake on the other hand, would get ported, but I would leave it just slightly rough, so as to cause a slight turbulance when the fuel/air hit it.

  3. #3

    Join Date
    Jan 2006
    The exhaust port is polished to slow down/discourage the build up of carbon which then reduces the size of the port, reduce flow and can impact port timing if the carbon build up is close to the exhaust port.

  4. #4

    Join Date
    Dec 2006
    Richmond Va.
    The build up of carbon in an exhaust port would take far longer than the engine would ever last. Polishing just the ex.port will most likely make no difference and just be a waste of time. There are mods that will make a difference but not polishing the ex. port only. Make sure the valves are clean and open fully.

  5. #5
    Flying Scotsman's Avatar
    Join Date
    May 2006
    Remove any rough stuff and port match the cylinders to the exhaust.
    Exhaust will work more efficiently with less obstructions.
    Smooth finish is best.

  6. #6
    Moderator OsideBill's Avatar
    Join Date
    Mar 2006
    United States
    Another exhaust mod that used to popular was extrude honing the entire system same philosophy as polishing the ports (removing casting flaws) less build-up and more efficient flow.

Thread Information

Users Browsing this Thread

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

Similar Threads

  1. Exhaust port polish , without porting?
    By chris1200 in forum Yamaha PWC Performance (2-stroke)
    Replies: 32
    Last Post: 08-15-2009, 11:33 AM
  2. FS: GP1200R Gasket Matched and Polished Exhaust Manifold
    By HopatcongGPR in forum Yamaha Classifieds
    Replies: 0
    Last Post: 06-30-2009, 07:53 PM
  3. FS SEADOO 787r engine, triple exhaust ports
    By bigborexpl in forum Sea Doo Classifieds
    Replies: 3
    Last Post: 07-02-2008, 07:56 PM
  4. Look at this exhaust port
    By J-ME in forum Yamaha Old School Skis
    Replies: 38
    Last Post: 03-25-2008, 09:38 PM
  5. Sanding and polishing Exhaust Mani for 780?
    By JGringo in forum Polaris PWC Performance
    Replies: 2
    Last Post: 11-18-2007, 06:51 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