Topic: '78 CB750F stiff throttle

[pmurph1x]

I've cleaned up the carbs on a '78 CB750F I'm trying to get back on the road. So far so good - on the bench anyway. One thing  I notice is that the accelerator is very stiff. The cables are very free but I believe the accelerator shaft spring on the carbs is very strong causing the stiffness. You can see from the pic it's a pretty beefy spring.

Doing a search it seems like this may be a common complaint on the '78 but I was wondering if anyone had found a way to relieve the pressure a bit? I could see it being an issue on long rides.

          Thanks

[Kyytsis]

I've have the opposite problem with a K7 - the cables are free etc, but the throttle return spring feels very weak.

[chickenman_26]

Doing a search it seems like this may be a common complaint on the '78 but I was wondering if anyone had found a way to relieve the pressure a bit? I could see it being an issue on long rides.

It is a common complaint. The stiff spring combined with the angle of the hand grips can make for some real wrist pain on a long ride. I replaced the spring on my '77 A with one from ACE. I kept cutting coils off 2 at a time till I got sufficient force to close the throttle reliably while not being so strong to cause discomfort.

Stu

[flybox1]

I've have the opposite problem with a K7 - the cables are free etc, but the throttle return spring feels very weak.

Slides gummed up? re-lubed your cables and throttle sleeve recently?

[flybox1]

pmurph1x, what are you using to actuate the throttle bell on the carbs if they are "on the bench"?

[pmurph1x]

Thanks for the responses guys.
Stu - I may try changing the spring down the road. I was just hoping that there was an adjustment to the spring tension so I wouldnt have to mess with new springs.

Flybox - I am turning the shaft by hand while on the bench.

Paul

[bjbuchanan]

Turning on the bench is gonna make even a limp spring seem tough. Between ratios and hand effort the feel will be much easier hooked up to the cables/ mounted on the bike.

[flybox1]

yeah, its a pretty stiff spring to actuate by hand.  as long as it snaps back, hard, when you release it, you're fine. dont change it.  leave it alone.  you really dont want a slow throttle return.  kinda dangerous when you're riding...dontcha think 
just check for the same snap back once you remount the carbs and attach the push-pull cables.

[steam-powered man]

i've lessened a stiff throttle by "unwinding" the spring, just a bit.  i've done the following:   

in your picture, unhook the left-hand end of the spring and "unwind" it, about 90 degrees iirc.  that end of the spring will rest against, i think, a shelf on the carb body.  i've had good luck doing this, and if your cables and routing are good, the engine will come back to idle nicely.

   

[pmurph1x]

yeah, its a pretty stiff spring to actuate by hand.  as long as it snaps back, hard, when you release it, you're fine. dont change it.  leave it alone.  you really dont want a slow throttle return.  kinda dangerous when you're riding...dontcha think 
just check for the same snap back once you remount the carbs and attach the push-pull cables.

I just put the carbs back on and you are right - its not too bad when having the push/pull do the work. Still not as easy as an old Shadow I had but I think I'll leave well enough alone for now.
   Thanks everyone for the help.

[pscycle927]

My 77 750k  is like that everything moves nice and easy on its own then hook everything up and twisting seems a little labored it snaps back great.  I guess I'm used to the old two stroke two finger blip and now Im trying to two finger  blip four of them at the same time. lol.