Honda-SOHC
SOHC.co.uk Forums => CB750 => Topic started by: El__burro on July 15, 2016, 09:48:00 PM
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As per subject line, my throttle is not returning freely.
The twist grip stays in the open position unless i twist it back.
Not sure if the problem is at the handlebar or carb mounting.
What's the first step you recommend.
Thanks
el__burro
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If you take too much slack out of the pull throttle cable then you get a conflict with the return one and the resulting friction makes operation really stiff.
Big coil spring on main lift spindle on carb assembly can wear through at one end and disconnect.
As a base line setup, if you detach the return cable at the carbs then see how it operates it will tell you if you need to go further..... Still too stiff? Also take off the pull cable then the main lift spindle should move easily with your fingers and snap shut easily, if not you are probably looking at the lubrication and cleanliness of the bearings supporting that shaft.
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Cable routing makes a big difference Also DO NOT lubricate the internals of the original cables as the inner is rubber coated and the outer is nylon lined and oil tends to make them swell into each other and bind
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Are you still using the Doherty twist grip with single cable or did you change it?
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When I bought my bike, (cb550) it was fitted with new aftermarket cables and routed wrongly which made the action very stiff.
After removing the cables,oiling them and rerouting as per the manual it made a world of difference.
Now have a smooth throttle which snaps back easily.
Best of luck with yours.
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The throttle comes from a VTR1000F and it fits nicely.
I am not sure about the routing.. (check the img attached).
Thanks
el__burro
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Also check the routing from the carbs, should go over the fuel tank brackets I believe? I had the same issue with mine when steering turned right. re-routed cable over the top of the fuel tank bracket, and all fine.
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Removed the tank and disconnected the return cable (bottom one).
It works fine.
Then I need to reattach the cable again and the problem is back.
any ideas?
el__burro
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I don't know what adjustment you've got on your cables, the standard ones usually have no adjustment for the return cable so no options there.
The pull cable has more scope so put all the slack you can get in that one and it should get rid of the conflict between the two. I know it sounds kinda back to front but it's how they are set up, you can then adjust the pull one a little if you need to but if you do, then check as you are doing it by turning the steering from full left to full right while twisting and releasing the throttle to make sure it doesn't bind again.
The Honda manual stipulates just how much slack the twist grip should have in it to avoid the cables binding but people tend to adjust them tight and think the throttle will somehow open further.
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Removed the tank and disconnected the return cable (bottom one).
It works fine.
Then I need to reattach the cable again and the problem is back.
any ideas?
el__burro
When you put the tank back on sounds like you maybe trapping/bending the cables in an awkward position
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Does the inner of the return cable move freely, particularly when the cable is in place?
Can't see what angle it is coming out of the twistgrip from the photo as the cables are underneath.
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Here are some pictures of the extremity of the cables.
When I unhook the lower (return) cable from the carb link it does fine.
el__burro
(http://uploads.tapatalk-cdn.com/20160719/fca02b749a1646612449496672cc3965.jpg)(http://uploads.tapatalk-cdn.com/20160719/586a9a6e666e4fe0083a70280b4fd1fa.jpg)
(http://uploads.tapatalk-cdn.com/20160719/a75101b1cb2b087a4afa799971fd9634.jpg)
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Looks like the opening cable is over tight, where the cable attaches to the carbs there should be a locknut either side of the bracket, in the picture you have both at the end of the cable bracket, try it with one nut either side.
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Might be too obvious but both of the cables look stressed where the flexible leaves the twist grip, they take an unnatural downward turn. Perhaps route them above that brake union? Not sure what the correct routing should be and how customised your bike is.
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A question, has it always done this, difficult to turn, since you had it going? Or has it changed?
When you disconnect the carb end of the return cable it will still be moving that cable but the action is ok. So it's not coming from the internal cable being stiff.
With both cables connected, is there any rotational slack at the twist grip at all and if so how much?
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;) why dont you just run the bike with just the pull cable .
i have done this for years with no problems in fact the action is a lot lighter with one cable anyway. go on you know it makes sense lol
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SORTED!
It turned out to be a routing issue.
See the pictures?
The cables were passing through the other passage in the frame.
I am very glad for your support.
Thanks a million
el__burro
(http://uploads.tapatalk-cdn.com/20160719/167af1711da1eecc372eb96f1c01cd4d.jpg)
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Glad you got it sorted,as I found out the correct routing makes all the difference.
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;) why dont you just run the bike with just the pull cable .
i have done this for years with no problems in fact the action is a lot lighter with one cable anyway. go on you know it makes sense lol
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Mines a K6 fitted with PD carbs, I find the throttle quite stiff compared to other bikes I have had, the new cables are routed as good as you can get them.
having recently had carpel tunnel surgery on my right hand 3 months ago I am now finding the stiff throttle a bit too much & after a good few miles of riding my hand & wrist aches like F*ck...
So today I have removed the throttle return spring & now its smooth & very easy...but i obviously now don't get the auto throttle/spring return, but at least I can give my hand a rest whilst riding without the spring closing the throttle, I just set the throttle in a cruise position & I can take my hand off the grip & relax it a bit
I know some will say its not safe having it this way "and if you drop the bike it will rev its bollocks off"
any other suggestions ?
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as the throttle grip on my Honda is worn,(well,it is original) I fitted a jubilee clip ,and in normal riding I use my thumb
to roll the throttle round,
saves having to grip to hard,
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Quote:
Mines a K6 fitted with PD carbs, I find the throttle quite stiff compared to other bikes I have had, the new cables are routed as good as you can get them.
having recently had carpel tunnel surgery on my right hand 3 months ago I am now finding the stiff throttle a bit too much & after a good few miles of riding my hand & wrist aches like F*ck...
So today I have removed the throttle return spring & now its smooth & very easy...but i obviously now don't get the auto throttle/spring return, but at least I can give my hand a rest whilst riding without the spring closing the throttle, I just set the throttle in a cruise position & I can take my hand off the grip & relax it a bit
I know some will say its not safe having it this way "and if you drop the bike it will rev its bollocks off"
any other suggestions ?
Johnwebley replied
as the throttle grip on my Honda is worn,(well,it is original) I fitted a jubilee clip ,and in normal riding I use my thumb
to roll the throttle round,
saves having to grip to hard,
Thanks John
just found this see photo below....might be worth try
Cruise Control Throttle Aid Cramp Buster Fits Onto Grip - CRUAID
Brand New / In Stock
Useful info:
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Which grips do you have on it?
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Which grips do you have on it?
These are mine 22mm anti vibe' grips 1st mage
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I raced moto-x in the distant past when there was all sort of grip materials and sizes sold as some sort of cure for anything you could imagine (bit like vitamins nowadays) but the ones that, for me, caused the least stress on hands and rists were the absolute thinnest I could get hold of.
It was just easier to hang on and race with my hands more closed naturally around the grip. Also the stickier the grip was then the less muscular clamping effort I needed.
Don't think Durex make bike grips ;) but the closest thing was trials bike kit.