Topic: Stiff throttle pull - lighter springs anyone?

[Zeke]

zeke,i went to the mcmaster-carr website,the one i found was an industrial supply type outfit.is that the same one?

Yo, D-dude:

Yeah, that's the right place.  You see, McMaster is where to find the hardware that you can't buy at Lowe's, or your local hardware store.  Sometimes you gotta buy bulk (fasteners) but they have alot of stuff.

It's a mechanical designer/engineers best friend for frequently used machine parts.  You can buy Orings there, bolts, helicoils, threaded inserts, wiring stuff, tools, SST tubing/fittings, SPRINGS...

Of course, you need to know a bit about what you want.

My bike uses a torsion spring, and I'll almost guarantee you wont find one at LOWE's.  You'd need to figure out the typical dimensions so it fits, THEN the tough part is figuring out the desired spring constant or torque.

Hmmm, let me see....

Torque is Force(pounds) x distance(inches).  You could test this in your garage pretty easily with a fish weighing scale.  With the spring fixed around a shaft(similar to how it is on your carbs), hook the scale on the free end and pull -- when you overcome the spring it will start to move -- stop -- you don't want it to move, you want to find the point of equilibrium BEFORE it moves -- record this number in pounds.  Measure the radius of the spring, or more precisely the distance from shaft center to point where scale was attached.  Multiply the force(in lbs from scale) times distance and this will give you the torque of the spring.  If you want a lighter spring, reduce this number -- hell, maybe buy a few different ones.

Using the springs from mcmaster, there isn't any hooks on the ends.  You can bend spring steel but only really once or twice and then it'll break.

I haven't tried this, but it might work well.  I've lubed the hell out of my cables as well and my forearms get pumped on long rides.

Anyway, hope this helps,

Zeke

[dusterdude]

cd811,would you please happen to have the lowes part number on that spring.

[cd811]

no but i'll be glad to look into it
no problem

[Quail "Owner of the comfortable k8"]

Make sure you lube the tube on the handle bar.  That and worn cables make it a bear to turn.

[dusterdude]

cd,that will be greatly appreciated

[cd811]

ok
sorry I'm so slow to respond
( I did a lot of acid when I was younger)
lowes part#c163...7/16 indiameter
use as is or cut to desired lenth
again sorry

[schneider419]

it sounds like you guys are on to something. but you might try this. it sounds like it's a coil spring. just un hook the top end from the linkage. take a pair of vise grips, clamp on to the end of the spring and pull the spring too far and hook back up. do this a little at a time untill you have the pressure you want.

[carsholduptraffic]

i have the same problem. the source of my stiff throttle is the worn bushes in the top of the carby, that guide the slide rods. as the lever (attached to the cables) lifts the carby slides, the angular force on the worn bushes makes them bind. how much they bind detirmines the return spring weight. i have done it all in an attempt to acheive that 'snap', but it boils down to that bush in the top cover. anyone know where i can get some? maybe a job for terry's magical workshop?
if i could have confidence in the throttles shutting when i let go of the throttle, i'd run a single cable, but then, the heavy, sticky throttle allowed me to ride 140km with my feet on the bars when crossing the nullabour! very comfy with a load to lean against!!!! highly recommended!!!

[jotor]

i have the same problem. the source of my stiff throttle is the worn bushes in the top of the carby...

...if i could have confidence in the throttles shutting when i let go of the throttle, i'd run a single cable...

Hmmm.....might be something there. I'll have to check that on my 400F.   Wonder if it's possible to ream out the holes and put in a brass bushing.  Maybe some of that thin wall tubing at the hobby shop.

I took the return spring completely off the 400F, just using the return cable to close it down.  It does work well as a "cruise control" but takes a bit of readjusting after riding other bikes.  Always wondered why they put a kill switch on 'em.   ;-)

[falcostan]

i dont understand the back off the spring thing,the spring is fixed in its windings,its not adjustable.

what i meant was stretch the last couple of turns on spring and re attach, like i say it may catch the carbs slightly but it works for me, me being an old codger of nearly 50 !

[dusterdude]

i installed new cables and greased up the handlebar where the throttle sleeve turns and it helped a great deal.

[cd811]

i was thinking about this situation(my throttle is tiresome after a ride).has anybody tried or thought about putting springs in each slide body(4) like on atc110 or185.(in place of the one pull spring)
it might make the whole system work easier plus as a bonus it might cut back on slide and needle flop...just a thought

[HondaMan]

The "fix" often applied by Honda mechanics like us was: overstretch the spring so that the resting distance is about 1/2 of the distance that you have to stretch it to install it. In other words, if the spring (off the bike) is 2" long and installed length at idle is 2.5" long, stretch it so that the resting length is 2.25" long. Install a fresh piece of hose over it (if yours is gone: they often are) and reinstall.

The hose helps you maintain a steady speed at highway speeds but "holding" the spring in stretch for you. DON'T remove the spring altogether! (Spoken by someone who has laid under a running bike while the rear spokes slashed at his thigh...)

[jdpas29]

try changing your routing on the cables so that they have less of a sharp curve in them.  i had some stiffness in the throttle on my 78 and that was the only thing i had to change to get it right.   

[the twig]

i had the same problem with my 350f. on my bike the problem was that the nylon twist under the hand grip was broken and the rubber twist grip was forcing the nylon onto the handle bar that made the throttle hard to use.good luck

[Hop on a Honda]

Cables.
two things which may give the impending thought of stuffed cables.
One.
Air filter clogged > creates too much vaccum in the Carb slides (4)  and it eventually gives the impression of tight springs or cable wear.

Two> you guessed it wrong route for the cables & more than likely wrong lube in the cable or the lube is OLD and has dried up .
It then becomes very stiff.
Good luck.
I use Silkoleene by FUCH was german?

Dave