Front Fork Question

Discussion in 'Sportster Models' started by nhk750, Dec 29, 2009.

  1. nhk750

    nhk750 Active Member

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    I have a dumb question.

    Bike XL1200C, 2008, 4000 miles

    The front forks when I sit on and am riding seem to be compressed almost all the way down. There is only about 2 inches of the fork tube showing. The bike seems to perform and corner correctly and has no high speed issues either. Is this normal for sportster forks to sit this low?

    I weigh 215lbs, probably 225 when fully geared up for winter riding. Should I change the fork oil or springs to heavier stuff?

    Thanks ahead of time for input.
     
  2. biscuit

    biscuit Junior Member

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    I read somewhere that about 25% of your total suspension travel is taken up when you sit on the bike in your riding gear.So if you've 5" of travel,you'll lose 1 1/4" when you hop on.Your figure seems excessive.
    Is this a new occurence?Has it always been this way?Have you changed anything lately?Fork oil perhaps?Have you noticed any oil dripping from your fork seals or the bottom of the forks?Has any "clunking" sound started up?

    IF this has been the case ever since you've had the bike,then look into it.Start by draining the forks,flushing them and then refilling with the correct ammount of fork oil.I wouldn't go to a heavier oil as this will give a harsher ride.Don't forget to check the condition of the seals.If in doubt,replace them.Should the problem still exist,either make up a small -say 1"-"spacer" to sit atop the forkspring inside the fork tube,or buy another set of springs from a suspension specialist.

    Or if you're happy with the existing setup,you could just leave it all alone.
    .
     
  3. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    That 2" is for rebound dampening...i.e. "--after the bump" the fork compresses even more, the oil valving allows limited recovery along with the compressed spring to handle subsequent compressions and releases (stutter bumps). Make the suspension travel less by over doing spring tension and oil weight will actually make ride worse and bumpy roads or rail road tracks a pain, or even dangerous! Follow manufacturer recommendations and change air pressure or preload, then oil weight (tuning suspension is an incremental thing and an art...also use zip tie on one of the forks to see the dynamic "stroke" your suspension goes through on one of your rougher "loops" before and after to be sure. Manufacturers like HD and Progressive have done plenty of research to optimize bike to rider weight AND do tell them about laden cargo and riding 2 up to be sure you are covered if you change major items.
     
    Last edited: Dec 29, 2009
  4. nhk750

    nhk750 Active Member

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    I guess it has always been this way. I never noticed it until my dirt biking friend pointed it out. Dirt bikes have a much greater travel of course. So, this looks to be normal for a Harley with basic spring/oil shocks.

    I could spend a bunch of money and make them better though with this stuff!

    Harley


    But, I didn't buy this bike to race, just relax and road ride...
     
  5. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    Nothing wrong with giving your suspension a "boost"...after all it is "only" $$$$ and time...BUT do so with understanding and manufacturer's recommendation for the type of riding you do. Street riding is a many varied thing, not like a race track which is suspension tuning set rather "taunt" for controlled track conditions. Street setting is much more free running using more of the stroke but with wider settings due to the fact the loading is different and you may want the bike laden for long distance touring or two up use, which complicates the tune, but Race Tech is like Progressive in that they have tuners who can tailor it to your specific application and needs...if you are willing to go the distance...literally...and the expense.
     
  6. fwcole

    fwcole Active Member

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    You can try a heavier oil but it can effect cornering.
     
  7. nhk750

    nhk750 Active Member

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    It comes down to money in the end...I think it will be what it is for a while...
     
  8. NEWHD74FAN

    NEWHD74FAN Experienced Member Retired Moderators

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    Easiest thing is to change the fork oil from approx. 5W to 7.5W using the recommended 9.5 oz to 10 oz amount in each (check service manual) for the correct amount or measure the amount you drain out with the forks unweighted...and do use tight fitting metric phillips head bit/hand impact tool for leverage to remove. See the Self Help Tips for details. I say this because it seems like the "standard" HD rider by design is estimated at 190 lbs and just under 6' tall.
     
  9. nhk750

    nhk750 Active Member

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    I will try that when I service the bike this spring. Funny, I always thought Harley riders were bigger!