RE: VM26 throttle return spring. Anyone found a lighter one?

[KEITH KRAUSE]

RE: VM26 throttle return spring. Anyone found a lighter one?

Anyone found a lighter spring that reduces hand fatigue but positively returns the throttle?
I've found a few at various websites that may work but I have no idea what the stock spring's "pull strength" is to compare. The free length of the stock spring is approx' 2" and 2 3/4" including the hooks. The spring is 1/2" wide. The wire diameter is .055". Would you figure out the pull strength by hanging a load on the spring and see when the spring starts expanding? That would seem like a pretty rough way of estimating it. Any help is appreciated.

 

[bwringer]

Darn good idea. Riding a VM bike can be rough on the wrist. There are good reasons for a strong return spring (VM carbs can "stick" open) but perhaps a little less spring enthusiasm would be safe enough? Not sure, really.

Anyway, measuring spring rate is pretty much exactly as you describe. You could use a fish scale to pull on the spring; there are digital and spring-loaded varieties fairly cheap.

I'd say pull until the spring opens 1/4" or so and see what you have, then continue to pull for another inch, measured as accurately as you can. From there you can figure out the working spring rate in pounds per inch, then convert to whatever units your candidates are using.

Hanging weights would also work, if you happen to have a selection of reasonably accurate weights on hand.


Also, if you Google "spring calculator" you may be able to make a reasonable estimate of your spring rate from the wire diameter, length, etc. Not sure how accurate that would be but it may be worth a shot.

Or, it would be cheap enough to order up a few candidates from McMaster-Carr and see what happens.

For example, this one has a slightly smaller wire diameter and about the same dimensions otherwise. $7.22 plus maybe three or four bucks for shipping for a pack of six.
https://www.mcmaster.com/9654k372

 

[salty_monk]

When I got the Skunk it had something "fabricated" on there & it was incredibly stiff. From memory I bought a pack of springs and played about until I got something that would reliably close the throttle every time with the lightest spring weight possible.

A couple of years later I got my hands on a "stock" spring. After switching them out one day it seems like I wasn't too far away...

I guess what I'm saying is that if you go much lighter than stock it won't return the throttle.

 

[salty_monk]

Maybe this is your answer:

https://www.thegsresources.com/_for...nd-K-amp-N-filters-to-do-a-VM-Carb-Conversion

 

[KEITH KRAUSE]

When I got the Skunk it had something "fabricated" on there & it was incredibly stiff. From memory I bought a pack of springs and played about until I got something that would reliably close the throttle every time with the lightest spring weight possible.

A couple of years later I got my hands on a "stock" spring. After switching them out one day it seems like I wasn't too far away...

I guess what I'm saying is that if you go much lighter than stock it won't return the throttle.

I'm thinking you're probably right about not being able to go much lighter. One spring I had that was made of noticeably thinner wire, was easier to expand but wasn't a night and day difference. It did make the throttle a little lighter but the return dragged a lot. Based on that experience, it appears the stock spring is actually just adequate instead of overkill.
Oh well, I think I'll just go with the stock spring. I was trying to find something easier on my wrist and avoid installing the Vista Cruise throttle lock. But the Vista seems like a good plan B. Thanks.

 

[KEITH KRAUSE]

bwringer, thanks for the reply and the link. Very informative.
I think the slides need just about all of the stock spring's return strength to close properly. Not much room for error. I'm just going to give up on the lighter spring idea and install a Vista Cruise which many here recommend.
Thanks again.

 

[steve murdoch]

 

[KEITH KRAUSE]

I do. Grosses my wife out to watch.

 

[Nessism]

If you haven't lubed or replaced the throttle cable lately doing so can make a noticeable difference. Clutch cable too. If you do decide to get new cables be sure to use OEM since they are better than aftermarket by almost all accounts.

 

[Drybear]

I used a M6 flat washer as a spring extender on the bottom end o the throttle spring to make it lighter.
It works very well together with this modification: https://www.thegsresources.com/_for...-Throttle-Mod&highlight=throttle+modification

 

[bwringer]

If you haven't lubed or replaced the throttle cable lately doing so can make a noticeable difference. Clutch cable too. If you do decide to get new cables be sure to use OEM since they are better than aftermarket by almost all accounts.

Excellent point. A new OEM cable is like buttuh. It would be well worth replacing it even if the old one doesn't seem damaged or nasty. Give your wrist the best chance possible.