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  1. #1

    Are there any specs on port and polish for a 750 sxi cylinder???

    Im about to port and polish my cylinders on my 750 sxi and I was wondering if there are any specs out there to go off of. Ive seen the porting done on other ski's and was wondering if there was anything I need to look out for or must do? Any help or advice would be great thanks!

  2. #2
    jonny5's Avatar
    Join Date
    Aug 2005
    Redding, CA
    Dont do it your self will probably go slower or turn to a tunning nightmare

    And before you port it if you do..have the ski completly running and run it and get numbers like rpm and mph...

    Then port it....and check again

    Some will just build a ski and say hey im gonna port it....put it together and think it rips and really it's not right.

    hope this helps.

  3. #3
    thanks for the advice. I had the ski running before I pulled it but my problem was too big of carbs. I have the novi 46's and factory pipe with MSD enhancer and everything else you can think of. I had a pro test it and try to tune it but couldnt because he said it was getting way to much air and gas for the engine itself to handle. He said the best thing to do to port and polish it. I have a stock 96' sxi head and I can see what the difference is between the two. The 96' is alittle cleaner inside and has a bigger intake. I have already started to make the intake and exhaust ports alittle bigger than the 96' but I didnt get to far, I mean only like 20 mins of work. Bytheway the 95' was pushing 7100 rpm's and about 51 mph but was dead at bottom mid and took forever to get it to peak. Any other advice??? Thanks for all your help!

  4. #4

    Join Date
    Apr 2007
    Lake of the Ozarks
    Be VERY careful not to mess with the tranfer roofs too much. The shape directs the mixture in the cylinder. You can clean up and widen the inside down. You can clean up the exhaust, but watch the port hight. this is like a cam in a car. Your pipe also needs to be tuned with the port hight.

  5. #5


    WE used to have to fix port jobs done by people with no insight of two stroke engines,if you raise the exhaust much more than 2mm you will loose tons on the btm.The best thing you can do is not port it but match up the ports and liner,and a proper chamfering job can add up to 10% horsepower on a stock engine,the novi 46mm are way too big for a kawa twin unless you are running a fully modified high rpm engine, you just wont get the cfm (airflow thru the 46ss they need)The transfer ports help push the exhaust gas out, if you change their direction you will just slow down.also polished intake ports sometimes dont give the proper turbulance to mix fuel and air properly,you can always polish your exhaust to help without causing damage,and you can chamfer and match liner and exhaust port in cylinder ,polish and grind any aluminum from casting out too,jmho>MArvin

  6. #6
    Join Date
    Mar 2008
    The 46s are too big?
    What pitch impeller and what diameter nozzle does this boat have on it?
    If you have no so called low end, run a smaller pitch impeller and make sure your nozzle is 80mm (sxi came with a 76mm nozzle)
    run 170lbs of compression and advance the spark if it isn't allready.

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