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Thread: Rotax 670 tuning

  1. #1
    Member Bullelkklr's Avatar
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    Default Rotax 670 tuning

    I have an old 1996 ski-doo Summit 670 that I put a rebuilt 670HO motor into. I am having carbureation issues with and can't seem to get it tuned.

    Is there a shop around anchorage that knows these OLD sleds that I could take it to for some help?

    At this point in the project a hundred or 2 dollars to get it tuned right would be a great stress reliever for me.....

  2. #2
    Member Bullelkklr's Avatar
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    Carbs aren't the problem. The issue is timing. The HO crank won't work with non-HO stator and flywheel. The timing mark is about 1/2 inch off.

    Back to try to get a HO CDI and DESS.

    Does the DESS plug into the CDI on a 1998/1999 Summit X 670HO setup ?

  3. #3
    Member Bullelkklr's Avatar
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    thought I should follow up on results:

    real problem ended up being that I had the lines for the HAC routed wrong and the CDI was producing intermittent spark...got it running fine and then I blew a head gasket during break in (or what should have been break in - next time I will take it easy for two tanks of fuel at least).

  4. #4
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    Go talk with Aj at snowmachine salvage.

    Sent from my Milestone X using Tapatalk
    Do I give my friends advice? Jesus, no. They wouldn't take advice from me. Nobody should take advice from me. I haven't got a clue about anything..

  5. #5

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    I went through that last winter. I tried to convert an HO to a standard 670 and discovered all of the timing issues, etc. I went ahead and got HO pistons and put it back stock. One other thing different on those is the RAVE plate is different for the HO than the regular 670. Mine ran great for the 50 miles I put on it last spring before the snow left. I picked up another HO this summer in cherry condition with a burned piston for a couple hundred bucks so I will be tearing that one down and doing a rebuild/shop class with my 7 year old on it this winter. DooTalk is a great place for information on all things SkiDoo.

  6. #6
    Member Bullelkklr's Avatar
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    I think that mine must have been a hybrid HO and standard motor - I didn't have any timing issues. The cranks were exactly the same and I utilized my old rave valves from the 1996 stock non-HO motor on the 1998 Summit X motor.

    The years between 96 and 99 on these 570's was definately dynamic for Ski-doo.

    I am going to replace the pistons without dipping into the bottom end (as I don't have the tools or knowledge to pull the bearings or pressure test the cases)....I will keep my fingers crossed and see how it turns out.....

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