FOAK: Throttle Spring Tension Question

Subject bike is a Kwak 550, the throttle does require a lot of effort
to over come
the return spring. It soon makes my hand tired because of all the grip
I need to generate.

Is this normal?

I am tempted to reduce the tension by weakening the spring. (I'll
remove it from the bike and heat a few coils until they turn red with
a propane torch.)

Can I simply remove the spring entirely and just roll the throttle
back and forth? Is there some safety reason why I shouldn't do that.

TIA

Biker Dude.

 

What sort of Kawasaki 550? IIRC, the early z550 had slide carbs,
replaced on later bikes (z550F, GT550, GPz550, Zephyr 550) had CV carbs,
which require less effort to open.

If your model has CV carbs, then I'd suggest changing the throttle
cable(s)[1] because it's probably gunged up. Same goes for slide carb
bikes, actually.

Whatever, removing the return spring is not a good idea. Yes, springs
and twin throttle cables[2] are a belt-and-braces idea, but from
experience, having done this myself, sometimes you go too far and you
make precise throttle control more difficult. And should a closing cable
ever break, you'll be in real trouble.

[1] Can't recall which/whether bikes had a twin throttle cable push-pull
set-up but it's not hard to tell: just look at how many cables come out
of the twistgrip.

[2] See above.

 

Somebody once said that lubricating the throttle cables might cause
deterioration of the teflon inner sheathing. You might want to do some
research into cable lubricants.

I went to my local hardware store and bought a weaker spring to
replace the garage door spring on a set of Mikuni round slide
smoothbore carbs. Good hardware stores have drawers filled with
specialty hardware.

If the throttle pull cable broke at a critical moment, you could kill
yourself.

 

Rather than try to modify the springs you've got on
there, I'd try replacing them. McmasterCarr has just
about any kind of spring you like although you're likely
to pay as much for shipping as for the order. I've used
off the shelf hardware store springs, though they tend
to be less reliable if you have to do any bending or
forming.

As others have suggested, you should also make sure
the cables are operating freely. You also ought to
check the twistgrip and make sure you really have
the stock springs in there to begin with.

 

Using the heel of your hand to operate the throttle just invites
carpal tunnel syndrome pain.

 

As others have said DON'T!

Nope get a cable lube tool and attempt to lube the cable(s) keep
applying the lubricant (aerosol OR non-aerosol) until it starts to
come out the other end of the cable. Then work the throttle a bit, let
is set overnight. Then next morning repeat this procedure (don't be
like me and set your coffee were it might get hit with overspary) work
the throttle a bit more.

Here is where it becomes a judgement call. IF the throttle
becomes easy to use, GREAT! You've solved the problem, now go out and
buy a second set of throttle cable(s) because if it was rust you are
likely to have one or both cable(s) break. DAHIKIJK Also now would be
a darn good time to lubricate any and all other cables per the owners
manual / shop manual. I've been where you are at and learned it the
hard way.

Good luck

 

Bollocks. Just replace the cables.

 

Dude you're talking to Krusty...only reason he knows anything is the
internet and even then he gets it wrong more often than not.

 

Thanks for the advice, I will replace the cables and then order up a
cramp buster.

If that doesn't do it then and only then will I look for a weaker
spring.

Asta la vista, baby!

Biker Dude

 

That'll work, take your time and pay attention to where things are
routed.