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  1. #1

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    carby settings for a 1020 big bore rotax

    Hi guys i am chasing a start point for the hi and low mixture scew settings for the tuning of my 1020 big bore rotox engine.

    Small story so you know what i am dealing with the more info i can give the better. I have bought a 951 rotax engine for my 2000 model gtx that is bored out to a 1020. I bought the engine with the carbs that the engine was tuned to with the jetting upgrades. As the engine was tunned to conditions in Alabama and I live in Australia the seller backed out the hi low setting 2 turns for me to tune to my conditions.

    The carby has the following specs needle and seat 2.3
    low jets are 90
    hi jets are 175
    I was told to run NKG BR9ES spark plugs. I am running my standard oil injection for convenience and i have read that this is quite sufficiant. the engine was origionally running premix 40:1. I wont to know what is the best start point for my hi and low mixture settings with these jets. I also read of a 1050 tuning set up of low out 1 1/2 and hi out 3/4 of a turn but it had different jets. I think the were 95 low and 167 hi. any help would be appreciated. cheers


  2. #2
    mibunkerking's Avatar
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    Lol. I bet that's kidd's old motor. He knows his stuff so just listen to him. Your settings are real close to what I have in my 1020

  3. #3
    SURFnTURF's Avatar
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    Quote Originally Posted by seadoo1020 View Post


    The carby has the following specs needle and seat 2.3
    low jets are 90
    hi jets are 175
    I was told to run NKG BR9ES spark plugs. I am running my standard oil injection for convenience and i have read that this is quite sufficiant. the engine was origionally running premix 40:1. I wont to know what is the best start point for my hi and low mixture settings with these jets. I also read of a 1050 tuning set up of low out 1 1/2 and hi out 3/4 of a turn but it had different jets. I think the were 95 low and 167 hi. any help would be appreciated. cheers
    Unless your running a coffmans exhaust your engine only requires jetting slightly more than stock.
    I have run these on a 1050 set up with no accelerator pumps.
    Lows 95 open 1 1/2 turn
    highs 170 closed
    2.0 N/Seat
    your set up will be way too rich down here.

    To give you an idea with jets factory pipe on their twin pipe set ups recommended 177.5 highs which isnt too far from your 175s.So you are going to be rich.

  4. #4

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    Spot on the money there mate,iit is kidds motor I am excited about this project. i have got it to a stage of cranking and it wont run. Just back fiers every now and then. I have enough spark to kill a horse so it is probly to rich.
    Last edited by seadoo1020; 08-25-2010 at 06:25 PM. Reason: need to cahnge it

  5. #5

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    Quote Originally Posted by SURFnTURF View Post
    Unless your running a coffmans exhaust your engine only requires jetting slightly more than stock.
    I have run these on a 1050 set up with no accelerator pumps.
    Lows 95 open 1 1/2 turn
    highs 170 closed
    2.0 N/Seat
    your set up will be way too rich down here.

    To give you an idea with jets factory pipe on their twin pipe set ups recommended 177.5 highs which isnt too far from your 175s.So you are going to be rich.
    Ah ok, Well so you know my skii is a 2000 modle gtx and i only have a single pipe system. It dose smell heaps rich and it wont run. What do you recommend jet sizes? can i run standard jets for now to get it to run?

  6. #6
    Kidd800XP's Avatar
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    Close the low speed adjusters in till it will run if you cant drop back to 95 lows. If you pumped the primer more then a couple of times you probably flooded it anyway. If your running the oil injection step it down to 95 lows and 175 highs. should be real close and maybe on the tad side of rich which will be fine not going to lose much power.

    Just so your clear on the jets I put in they are
    100 lows
    180 highs

    I made sure it was going to be rich so you dont blow it up and gives you a hands on for the turning part. You asked so many things prior to purchase it really seemed like you didnt want to due the initial set-up on your own and was trying to be cautious on tuning

  7. #7

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    Hi mate. yeh I am all about hands on. I am learning so much about this thing it not funny. In 1 of the emails it said the carby was set up with 90 lows and 175 hi. But i guess not lol. I have some jets ordered for trial tuning. I have some 90 and 95 low jets and 165 and 170 hi coming. Hopefully i can sort something with that. the standard jets are 75 low and 162.5 hi. Its all about havin a go and not trying to blow it up!!!! any further advice would be cool. I am going to try 90 low and 170 hi first.

  8. #8
    SURFnTURF's Avatar
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    Quote Originally Posted by seadoo1020 View Post
    I am going to try 90 low and 170 hi first.
    Sounds like the pumps have been removed so I would use 95 lows and 170 highs closed but even that will be to rich IMO i would use 167.5 highs closed. The stock needle and seat 2.0 mm flows more than enough fuel for your application but use a black 85 gram spring to get you around 20 21 psi pop off.Here http://www.greenhulk.net/forums/show...-Pop-Off-Chart

  9. #9

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    Quote Originally Posted by SURFnTURF View Post
    Sounds like the pumps have been removed so I would use 95 lows and 170 highs closed but even that will be to rich IMO i would use 167.5 highs closed. The stock needle and seat 2.0 mm flows more than enough fuel for your application but use a black 85 gram spring to get you around 20 21 psi pop off.Here http://www.greenhulk.net/forums/show...-Pop-Off-Chart
    Thanks bud will take that advice.I am going to play with this and see how i go. I will post my reults

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