Author Topic: Throttle spring!!!  (Read 2455 times)

Offline TrickyMicky

  • SOHC Expert
  • Posts: 474
    • View Profile
Throttle spring!!!
« on: July 26, 2025, 05:09:34 PM »
Greetings people, I am just wondering if anyone has managed to fit a throttle return spring of less strength. I have reached the age now where when riding round twisty lanes that need constant speed changes, my poor old right wrist is starting to give me hell. NO! it's totally unconnected with any nocturnal naughties!!!  Considering that it is fitted with a push-pull cable set up, I cannot see the need for such a strong spring.  I tried one of those 'paddle' gizmos thatb sit under the heel of the thumb, but when pretending to be Hailwood, plenty of front brake and blipping the throttle as you change down it got in the way and was quickly sent on its way to the back of the garage.

Offline Mikep328

  • SOHC Expert
  • Posts: 455
    • View Profile
Re: Throttle spring!!!
« Reply #1 on: July 26, 2025, 05:26:09 PM »
I'm also interested.  I tried to find a suitable spring when I was rebuilding the carbs but no luck.  As noted, it definitely does not need to be so stiff.  I also have tried one of the paddle thingies but I wasn't as considerate as you...I threw mine in the rubbish bin!
Mine:
1976 CB400F
1973 Norton 850 Commando
2015 BMW R9T
2017 BMW R1200RS
2021 Moto Guzzi V7 Special
Wife's:
2015 Ducati Diavel
2019 Honda Africa Twin
2019 Honda NCT750

Offline exvalvesetdabbler

  • SOHC Expert
  • Posts: 354
    • View Profile
Re: Throttle spring!!!
« Reply #2 on: July 26, 2025, 07:01:50 PM »
Heaven forbid but if the bike is lying on its side with you stuck under it, it's reassuring to know that the bike can close the throttle all by itself.

If I was going to mess about with that I would probably try a washer hooked on the spigot where the spring goes and drill a small hole in the washer to reattach the spring, should reduce the tension a bit.  A small chain link might be another  option to take a few mm off the spring tension.

Regards
Dave

Offline Mikep328

  • SOHC Expert
  • Posts: 455
    • View Profile
Re: Throttle spring!!!
« Reply #3 on: July 26, 2025, 07:12:01 PM »
"Heaven forbid but if the bike is lying on its side with you stuck under it, it's reassuring to know that the bike can close the throttle all by itself."

And that's probably why it's designed that way!  I like your idea re a washer/chain link, etc.  Might try that next time I have the carbs off though I'm hoping I'll have no reason to remove them for years!  :) 
Mine:
1976 CB400F
1973 Norton 850 Commando
2015 BMW R9T
2017 BMW R1200RS
2021 Moto Guzzi V7 Special
Wife's:
2015 Ducati Diavel
2019 Honda Africa Twin
2019 Honda NCT750

Offline Seabeowner

  • SOHC Master
  • Posts: 1107
    • View Profile
Re: Throttle spring!!!
« Reply #4 on: July 26, 2025, 07:15:31 PM »
If the 400 is similar to the 500/550 then even when the slides are fully down there is still a lot of force and the spring is quite stretched. So similar to what's written above I used a small keyring type loop at the top end to reduce the stretch. Just make sure it still closes securely, mine does.
Phil
1971  CB500K0  Candy Jade Green or Candy Gold
1973  CB500K1  Candy Ruby Red
1975  CB550F1   Shiny Orange