Author Topic: Fork Spring Mod - Advice needed...  (Read 4852 times)

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Offline CRocker

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Re: Fork Spring Mod - Advice needed...
« Reply #25 on: July 11, 2012, 02:56:26 pm »
Put the front wheel back on...new bearings and new Shinko SR733 130/70H18 tire...fork oil was changed from 10wt to 15wt when I cut 3.5" off the stock springs and used a 3.5" PVC spacer with washer under...I wanted to change as little as possible at this point to answer a question...

My 5 mile ride this morning made me feel much better...bike stands taller in front...not as much dive under braking...and, still has a supple ride that soaks up many road irregularities...

BBroj...if you are riding on the stock springs...and find it to be too soft...or, if there is a little too much dive in the front end...do it.  It cost me less than $5 plus the fork oil...I used a mitre box and hacksaw...and I bought new hacksaw blades out of that $5!

Thanks, again to the collective wisdom of those on this forum...it's great when things work out exactly as planned!   :great:

Offline Daytona_Mike

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Re: Fork Spring Mod - Advice needed...
« Reply #26 on: July 11, 2012, 07:38:10 pm »
Glad you got it done. The brake dive on stock springs is so excessive to the point that some of us heavier folk  can  easily compress the forks right to the bottom making it a safety issue.
You solved that problem and you got a better handling bike. Congrats!
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Offline CRocker

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Re: Fork Spring Mod - Advice needed...
« Reply #27 on: July 12, 2012, 12:30:36 am »
Mike,

Yeah...but you didn't tell me how easy (NOT!) it would be to get the fork caps back on by myself...I'm still sore!   :))

Offline Strawboss

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Re: Fork Spring Mod - Advice needed...
« Reply #28 on: July 12, 2012, 12:20:07 pm »
OK, I'll try the cut stock springs OVER the sonics with emulators and no spacers. I want to get it softer than what it is now but still try to retain the anti-dive effect the sonics provide but still be a tad stiffer than stock. Sounds goofy huh? I'm willing to try anything now.
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Offline Daytona_Mike

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Re: Fork Spring Mod - Advice needed...
« Reply #29 on: July 12, 2012, 02:16:44 pm »
Well, you have a good start with using emulators. They can be tweaked quite a bit.
One thing I learned to do is put a tie wrap on the  fork. After a spirited ride you can see how far you compressed the front end.
I have Sonic 1.2's, 20 weight oil and emulators and I was surprised to see the tie wrap all the way to the top. I had compressed the front as far as it would go and bottomed the suspension out. That is not good. We did the same thing to a stockC14 and his suspension also bottomed out and that was not an aggressive ride.
Dont forget to check your  static sag rate after your done changing the suspension.
You do not want  ride the bike without it being at the correct geometry. I think (rough guess) you want about 1.25" of sag on the front.
This is from the RaceTech website:
STANDARD STREET AND SPORT BIKES
TYPICAL PRELOAD RANGE for STREET FORKS - 15 to 30 mm (5/8 to 1 1/4")
STANDARD PRELOAD - 20 mm (0.8") (using RT recommended rate) If your model has Preload Adjustment and you are making spacers, cut spacers to set the minimum adjustment to 15 mm (5/8").
PRELOAD EXTREMES FOR STREET FORKS - 5 to 35 mm (1/4 to 1 1/2")

More Preload for heavy bikes or when using softer springs.

    MEASURING STATIC (RACE) SAG

    Static Sag is the amount the bike settles, from fully extended, with the rider on board in riding position. First, extend the forks completely (bike off the ground). Measure from the wiper to the bottom of the triple clamp on conventional forks or from the wiper to a point on the axle clamp on inverted forks. This is L1.
    Take the bike off the stand and put the rider on board in riding position (Street - sitting or Road race - full tuck). Get an assistant to balance the bike or have the rider hold onto something. Push down on the front end and let it extend very slowly. Where it stops, measure the distance between the wiper and the bottom of the triple clamp again. Do not bounce. This is L2. (If there were no drag, the bike would come up a little further.)
    Next, lift up on the front end and let it drop very slowly. Where it stops, measure again. Do not bounce. This is L3. The reason L2 and L3 are different is due to stiction or drag in the seals and bushings. (If there were no drag, the bike would drop a little further.)
    Half way between L2 and L3 is where the Sag would be with no drag or stiction. L2 and L3 must be averaged to find the midpoint and subtracted from L1 to calculate true Static Sag.


    Static Sag = L1 - (L3 + L2)/2

    To adjust Static Sag use the preload adjusters, if available, or make longer or shorter preload spacers.
Normally aspirated engines have perpetual turbo lag
2000 Red C10 1052 kit 100+HP  + way more torque.
2008  C14 Silver Dammit Full AreaP- Flies are put back in SISF_Flash
2011  KLR650   688 piston ported and polished
2011  KTM 530    This thing is FUN!!

Offline Strawboss

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Re: Fork Spring Mod - Advice needed...
« Reply #30 on: July 12, 2012, 03:46:09 pm »
Mike, not to be flippant, but I've read all the explanations and seen all the calculations and they are absolute Greek to me. I haven't a clue as to what I've got and for the life of me cannot tell the difference if my life depended on it as to whats 20mm of pre-load to 35mm to whatever. I use the .95's, with the emulators at two turns from just touching, and fork factory pre-load set with 2 lines still showing, blue emulator springs and straight 15wt oil, oil set at 171mm or 6 1/2 inches from the top with forks compressed and nothing in the tubes, and a 6 inch PVC spacer with washers at both ends of the spacer, the spacers are about flush with the tops of the tubes, its just ok, still a bit jarring. But, I read this stuff and forget it, makes no sense to me and I've tried reading it 20-30 times.  Sorry, but I just want a smooth ride and I'm not finding it and I'm not impressed at all with all the things folks are saying about how much improved the ride is, about the ONLY thing I can say about the emulators and sonic springs are the front end doesn't dive much compared to stock. 
01 Concours  1982 KZ550A  1979 Triumph Bonneville  1995 Honda scooter 1982 CB125s 1980 BMW R-65  COG#5852  AMA Life 302525  NRA 9098599  SASS 28759