Throttle not "snapping back"

imtaylors

imtaylors

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Hey everyone!
I am new here and also a proud new owner of a 1981 XS650. Love it. I needed to clean out the carb and replace some stuff, got a new cable (yes I lubed it up) and a new throttle sleeve and grips. My only thing is, it is not snapping back like it used to, and I am stuck, I have tried looking online, in the manual, and I haven't found anything. If any of you could help that would be great. Can't wait to learn more about all of this!
 
First just remove the cable at the carb, only takes a couple of seconds, does the carb work freely? Yes? then take off the gas tank, free up the cable from any pinches, tight bends, up by the triple tree, does that help?
 
Perhaps take the throttle apart. See whats dragging. Is the cable rusty? Throttle shaft turn easy? Are the carbs CV or plunger style? Pics are always useful.
 
gggGary said:
First just remove the cable at the carb, only takes a couple of seconds, does the carb work freely? Yes? then take off the gas tank, free up the cable from any pinches, tight bends, up by the triple tree, does that help?
Click to expand...
It is a new cable, I lubed it up, the gas tank is off, there is no binds or pinches or anything like that.
 
azman857 said:
Perhaps take the throttle apart. See whats dragging. Is the cable rusty? Throttle shaft turn easy? Are the carbs CV or plunger style? Pics are always useful.
Click to expand...
Okay ill take it all apart, see whats going on again. the cable works fine, it is a new cable, its a new grip and sleeve and everything. and i am pretty sure its a cv carb! Let me take some pictures for all of you when I get home!
 
First......welcome to the forum imtaylors:)

gggGary said:
First just remove the cable at the carb, only takes a couple of seconds, does the carb work freely?
Click to expand...

This is an excellent suggestion from G because at a stroke it will confirm if your problem is due to the carburettors or the cable/s & throttle assembly . You can potentially eliminate unnecessary checking and concentrate your attention where the problem lies

If the throttle shaft return springs haven't been reassembled on the correct carb (they have different strengths on BS38s and may have on your BS34s ) or haven't been assembled on the shafts with the correct number of pre-turns then that could cause a slow/ weak throttle return.

Your carbs are presumably BS34 . it might be necessary to add some additional spring/s to the throttle shafts to compensate . Your original return springs will have lost a lot of their spring strength over the years and aftermarket replacement springs may give little improvement.

I attached a strong coil spring to my throttle shafts and the throttle shut down is now nice and snappy ;)
 
I remember one time my throtlle assembly moved too far over the handlebar. That made it come back very slowly or sometimes was even stuck. After I fixed that I placed as an extra a very simple small coil spring between the vacuum port and the throttle lever on the carb. Works fine and gives me some extra security that the throttle will close when the cable might get stuck somehow. Don't know if that will really work, but it gives me a little confidence that it will close :)
 

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imtaylors said:
Okay ill take it all apart, see whats going on again. the cable works fine, it is a new cable, its a new grip and sleeve and everything. and i am pretty sure its a cv carb! Let me take some pictures for all of you when I get home!
Click to expand...

Hi imtaylors and welcome,
Yes, please post photos.
Your posts keep saying CARB, singular.
When the bike left the factory it had two of them.
If a dreaded PO has been messing with it, anything is possible.
 
5twins said:
There should be a rather large coil spring around the casting that the butterfly shaft sticks out of .....
Both carbs should have one ...
Click to expand...

Nope, I got just one spring. Funny though, I just went through some old pictures when the bike first arrived but I see no spring. I think I'll order one next time at Heiden. At least if he's got one cos I think they're hard to come by. But for now my 'bush fix' is working just nicely since 2011 :)
Oh well, necessity is the mother of invention ain't it?
Thanks for clearing that up and many thanks for the pictures 5twins!
 
Yamaha never listed or sold this part so I doubt Heiden would have it. Scrounging one is probably your only option. As was mentioned earlier, the spring on each carb is different, one stronger than the other. You can plainly see the spring wire thickness difference in the pic.
 
5twins said:
Yamaha never listed or sold this part so I doubt Heiden would have it. Scrounging one is probably your only option. As was mentioned earlier, the spring on each carb is different, one stronger than the other. You can plainly see the spring wire thickness difference in the pic.
Click to expand...
I guess you're right about the availability of it. It's indeed not on Heiden's or any other websites. Well there is a used motorcycle parts shop nearby, I'll ask around next time I visit those guys. They do have XS parts. I noticed the difference in springs. It's clearly visible on the pictures. :thumbsup:
 

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