Topic: Tight/stiff throttle spring k7 750

[Pielz]

Does anyone have any specs on what I could look for when replacing my throttle return spring? I'm not sure if it's just old and work hardened or what but it's incredibly tiresome to hold open while riding. I have to squeeze the grip so hard to keep it from snapping back that I lose feeling in my fingers after only 20 mins or so lol.

[dusterdude]

No,that's the way it is.I put a hardware store spring on mine

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[Pielz]

Okay good. So I'll just take the spring in to home Depot and see if I can find a similar one. Thanks!

[seanbarney41]

Everytime I think it is time to change to a lighter spring, I end up r and r-ing my throttle, cables, and carb linkage.  I end up finding something wrong that cures the problem without changing springs.

[Pielz]

I actually just put new cables on, and just recently had the carbs apart and cleaned and lubed. Even pulling the linkage back by hand takes about all the force I can exert with my fingers. With the spring off it moves really nicely.

[seanbarney41]

Yeah, sounds like you got all the bases covered but I can tell you that everytime I have done the same, I still have always found something causing that heavy throttle feel.  These will never have the light feel of cv carbs or modern flatslides but they can get pretty good.  Most times I have found it's either cable routing or adjustment. 

I dunno...lots of folks report success with lighter springs.  Personally, I have always found a problem to fix easier than I can find a spring that fits, functions, and is safe.

[Pielz]

Thanks, I'll double check my routing and that my cables are oiled well! Ive been meaning to buy a cable oiler

[Erny]

I made the same exercise

I first checked all - everything was working fine, cables, carbs mechanics etc. Then I replaced spring by 2 paralel smaller/lighter I found in my garage (1 was not enough as trottle was not returning reliably), later I ordered 1 lighter spring that I'm using now. Trottle won't be perfect, I know, but is good enough to ride and not be disturbed by pain in the right wrist

[pjlogue]

I replaced my '76 spring with one I found in Lowes.  Same diameter and length but lighter (thinner wire) spring force.  Your cables should have a slight bit of slack between the two cables.  ~1/8" play before the cable starts to pull the throttles open.  Also, where the cables attach to the carb bank, the line should be as straight as humanly possible and any curves in the cables need to be a wide arc.  I have mine coming off the handlebars in a large swoop and going down between the left headlight bracket and headlight bucket and from there straight to the carb bracket. 

Slight tension in the two cables will make for a huge increase in twist force.

-P.

[BenelliSEI]

+1 to JPL. K7/8s we notorious for heavy throttles. You’ll have to get the cable routing right if you lighten return springs. I’ve often wondered: if I nicely balanced the “push and pull” cables, could I run without a return spring?

[Phoenix]

On my k1, i just took the spring out and stretched it a little.  Works fine.

[pjlogue]

+1 to JPL. K7/8s we notorious for heavy throttles. You’ll have to get the cable routing right if you lighten return springs. I’ve often wondered: if I nicely balanced the “push and pull” cables, could I run without a return spring?

I had once thought about removing the spring and tried it many years ago.  What happens is the carbs will not properly return to idle  unless you actively force them closed with the return cable.  It was annoying!  It is also a safety feature in case the return cable gets bound up.  You would then be stuck until you fixed or replaced the return cable.

-P.

[beemerbum]

+1 to JPL. K7/8s we notorious for heavy throttles. You’ll have to get the cable routing right if you lighten return springs. I’ve often wondered: if I nicely balanced the “push and pull” cables, could I run without a return spring?

I've been using the "poor man's cruise control" I can't remember the name of the device but it fits on the throttle grip and utilizes the heel of your hand to help in turning the grip. Works very well on my K7

[Pielz]

I went to home Depot and grabbed a slightly weaker spring that may work. I did order one of those things you're talking about beemerbum. It should be here tomorrow. I got one that straps on and is about half as wide as the ones motion pro or cramp buster makes. I didn't like the idea of having to get used to the mechanics of it if you know what I mean. Like having to lift my palm to reset it before I accelerate again. At least that's the impression I got from the reviews of those things. We'll see how it goes!

[Pielz]

Little update for anyone who wants to know: I took the spring off and tried to replace the spring with the weaker one I bought. Unfortunately it was too weak. Lol. So I pulled the stock one a little with pliers and put it back on. It helped a little. I also got this:

https://www.amazon.com/dp/B07W9LWB9V/ref=cm_sw_r_sms_apa_i_izx7EbGWST0E3

It works pretty nicely! Requires about half as much effort as before.

[lowriderbud]

Like somebody already said, the '77 & '78s have real heavy return springs.  I used my Dremel Tool with a cutoff wheel to remove 2 1/2 turns on the original spring.  Made a new hook in the end and re-attached.  Worked perfect...

It's still a good idea to have the cables properly routed, adjusted and lubed.