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    Default 39mm 4over Fork oil level

    I have a chopper Iím building from a sportster. I bought 4 over tubes, shaved the lowers and now Iím reassembling them. I put the required oil level in, 10.5 ďdryĒ and to me they still feel spongy. I have a 4Ē spacer that came with the tc brothers kit. So I know thatís not it, and the oil is Harley for oil E. Iím hoping someone knows the amount needed/weight needed for normal response.

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    The level sounds right...

    How do you know they feel spongy?? Have you ridden the bike or are you just pushing it up and down sitting still???

    Have you ridden an extended front end before?? They are different...

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    I haven’t ridden an extended front end and yes just pushin it up and down on the floor compared to what the old ones felt like.

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    Quote Originally Posted by Hammerhead2124 View Post
    I havenít ridden an extended front end and yes just pushin it up and down on the floor compared to what the old ones felt like.
    They do feel different, Not to worry you will be fine you don't want to much oil.

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    I think another way to measure, on a stock length anyways, is to measure a certain number of inches from the top.
    I don't know what that number is nor do I know if this is the case with an extended front end.


    You can try a heavier weight oil but then it gets harsher on square edge bumps.
    How much do you weigh? Could you need heavier springs?
    Last edited by hillcat; 05-11-2018 at 11:45 AM.

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    If I am not mistaken, fork tube length has nothing to do with quantity of fork oil. Put in the amount that the stock forks require. Make a longer spacer out of PVC pipe to add some preload.

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    Quote Originally Posted by vonhelmet View Post
    If I am not mistaken, fork tube length has nothing to do with quantity of fork oil. Put in the amount that the stock forks require. Make a longer spacer out of PVC pipe to add some preload.
    Yes sir you are right.... It doesn't matter how long the tubes are it's the same amount of oil...

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    Quote Originally Posted by Tattooo View Post
    Yes sir you are right.... It doesn't matter how long the tubes are it's the same amount of oil...
    This was not the case when I went 6 over. My forks kept topping out until I added more oil.

    Here's another thread with the same issue and solution.

    http://www.chopcult.com/forum/showth...t=42648&page=2

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    that thread is inconclusive and ask many of the other people here who've done the same thing, you just put the stock amount of oil in it. im not even sure how you could tell if they are spongy, but something else may be wrong with your installation. if im wrong and someone proves otherwise ill delete this but imo thats all i did and i had 10 over forks, 4 over forks, rebuilt forks, and its always the same to me

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    Quote Originally Posted by FatChibs View Post
    that thread is inconclusive and ask many of the other people here who've done the same thing, you just put the stock amount of oil in it. im not even sure how you could tell if they are spongy, but something else may be wrong with your installation. if im wrong and someone proves otherwise ill delete this but imo thats all i did and i had 10 over forks, 4 over forks, rebuilt forks, and its always the same to me
    You are correct, It doesn't make a difference when you go longer in tube length....

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    Quote Originally Posted by Savwha View Post
    This was not the case when I went 6 over. My forks kept topping out until I added more oil.

    Here's another thread with the same issue and solution.

    http://www.chopcult.com/forum/showth...t=42648&page=2
    I agree with FC... My bet is you didn't have enough fluid in there in the first place.... But if it worked for you that's all that matters...

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    OP can also add more preload with longer spacers if he wants.

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