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Thread: Finding a Weaker Carb Return Spring

  1. #11
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    Quote Originally Posted by RichDesmond View Post
    Back in the dim times, before CV carbs became ubiquitous, I’d see an ad in the back of every bike mag for a device called Twist-Assist, or something close to that. Might be worth searching eBay or other vintage bike forums for one.
    Yep, "Twist Assist" is correct, I had those on my first few bikes.

    It was a tube with an internal spring that would slide into the right side of the handlebar and expand to lock in place. There was a threaded stud on the end of the spring that would stick through the end of the rubber grip. By winding some counter-pressure on the spring and squeezing the end of the grip, it would counteract the spring on the carbs.

    It could be adjusted to perfectly balance the carb spring, which would require you to manually move the grip in both directions. You could also over-adjust it so it would ADD throttle when you let go. Yeah, you could also add spring resistance if you needed to add some muscle tone to your right wrist.

    .

    mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
    hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
    #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
    #2 son: 1980 GS1000G
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  2. #12
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    Quote Originally Posted by Steve View Post
    Yep, "Twist Assist" is correct, I had those on my first few bikes.

    It was a tube with an internal spring that would slide into the right side of the handlebar and expand to lock in place. There was a threaded stud on the end of the spring that would stick through the end of the rubber grip. By winding some counter-pressure on the spring and squeezing the end of the grip, it would counteract the spring on the carbs.

    It could be adjusted to perfectly balance the carb spring, which would require you to manually move the grip in both directions. You could also over-adjust it so it would ADD throttle when you let go. Yeah, you could also add spring resistance if you needed to add some muscle tone to your right wrist.

    .
    And the big advantage of that system is that if you close the throttle the full force of the stock spring is pushing the slide down, unlike if you fit a weaker return spring to the carb.
    Rich Desmond
    1980 GS1000S
    2007 V-Strom 650
    2008 Ducati 848
    2002 DR-Z400S
    1999 SV650 (race bike)

  3. #13
    Gorminrider is offline Forum Sage Past Site Supporter
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    You could increase the diameter of the grip. This will increase leverage turning AND holding....and your hand will not need to clench as far so fewer wrinkles of your hand or gloves might increase "grip versus pressure.."
    possibly mock this idea up with some handy materials (wrapped leather, foam wrapped with grippy hockeystick tape and go round the block) before you buy stuff

    If you find that WOT too slow, you MIGHT try increasing diameter at just one place or two places on the grip...under a knuckle...this is merely an idea.

    Grips with raised longitudinal bars in the moulding might also help.
    Last edited by Gorminrider; 09-15-2020 at 02:26 PM.

  4. #14
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    I use this throttle tube on my gs425. The holes are positioned differently than the stock throttle tube so the acceleration has a much lighter feel. I use only 1 throttle cable as well (the one closest to the front of the bike) and lube the inside of the cable. It fits perfect on my handle bars which have an OD of 22.2mm. Not sure if it will make a difference on the 750? But definitely gives mine a lighter, easier feel.
    https://buyee.jp/rakuten/detail/auc-pretty%3A10004640

  5. #15
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    Not sure about anyone else, but I'm REALLY hesitant to buy something I can't read.

    .

    mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
    hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
    #1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
    #2 son: 1980 GS1000G
    Family Portrait
    Siblings and Spouses
    Mom's first ride
    Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
    (Click on my username in the upper-left corner for e-mail info.)

  6. #16
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    Quote Originally Posted by Steve View Post
    Not sure about anyone else, but I'm REALLY hesitant to buy something I can't read.

    .

    Google translate is quite the awesome thing. It just came out 15-20 years ago.

    ☆ Made by PRETTY RACING ☆ ○ The contents of the exhibition are hollow aluminum throttle + 3 throttle spacers SET ○ Compatible models = GS400 (all year) / Sanpachi (all year) / 400 Zarigoki / ○ Safe and secure one-piece structure aluminum throttle ○ Throttle Because the finish of the inner surface is beautiful, the accelerator slides smoothly and smooth accelerator work is realized ○ The inner surface of the throttle has a straight structure ○ The big difference between 01 and 02 is that the size and height of the stopper are different and 02 is larger This will prevent the throttle from spinning. 〇 The throttle spacer will be a spacer to fill the looseness between the throttle and the switch box in the switch box, and you will not have to worry about interference with the grip with an external spacer. * Please purchase separately as it is not required for the GS400 early model switch box. ○ We recommend those who can maintain the installation or install it at a motorcycle shop. 
    1983 GS 550 LD
    2009 BMW K1300s

  7. #17
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    I had the same problem on two of my then new bikes,74 GT 750 and 78 GS 1000. On both I found a place on the carb rack to put a small bracket and hardware store spring configured to open the throttle. I sized the spring so It would assist opening and counter some of the factory stiffness. A couple of adjustments to spring length were necessary to get it right but when I did the spring pressure was cut drastically and made them very comfortable to ride. There was still enough so the throttle would close completly when I let off.My current 83 gs 1100e does'nt really bother me so it's ok as is.

  8. #18
    gbw's Avatar
    gbw is offline Forum Sage Past Site Supporter
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    I feel your pain. My 77 GS750 had a tough throttle. I used a cramp buster. It helped. Some people hate them, but it made the bike ridable for me. You can pick them up for like $10. So it's a pretty cheap experiment.

    I don't seem to have this issue on my newer bikes.
    Current: 2009 Triumph Tiger 1050, 1996 DR350SE
    Previous: 2007 GSF1250SA Bandit, 2008 DL1000 V-Strom, 1977 GS750B

  9. #19
    KEITH KRAUSE's Avatar
    KEITH KRAUSE is offline Forum Guru Charter Member
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    Quote Originally Posted by salty_monk View Post
    I messed around with springs on the 78 1000 (probably the same as yours). At anything noticeably less than stock it doesn't snap shut as it should....
    Same here. '79 GS1000. There is no perfect spring.
    And on the seventh day,after resting from all that he had done,God went for a ride on his GS!
    Upon seeing that it was good, he went out again on his ZX14! But just a little bit faster!

  10. #20
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    METAL COAT HANGER. Make an "S" hook with one end closed to hook the spring to and an open end that goes over the stud on the rack. Experiment to be sure the throttle linkage returns reliably. Less stretch means less pull at the grip.

    Ive done this and have had no issues....
    Last edited by chuck hahn; 09-20-2020 at 03:33 PM.
    MY BIKES..1977 GS 750 B, 1978 GS 1000 C (X2)
    1978 GS 1000 E, 1979 GS 1000 S, 1973 Yamaha TX 750, 1977 Kawasaki KZ 650B1, 1975 Honda GL1000 Goldwing, 1983 CB 650SC Nighthawk, 1972 Honda CB 350K4, 74 Honda CB550

    NEVER SNEAK UP ON A SLEEPING DOG..NOT EVEN YOUR OWN.


    I would rather trust my bike to a "QUACK" that KNOWS how to fix it rather than a book worm that THINKS HE KNOWS how to fix it.

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