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TOPIC: uncontrolled revving

uncontrolled revving 2 weeks 6 days ago #26802

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My bike is 1982 kz 1300-A4 . On easy start up, the motor goes into immediate high revving >4000rpm so I hit the stop button.Repeated after trying to get fast idle and gaps and idle adjusting correct...

This is what I have done:
1.Stripped and "Scotch" cleaned carbs , triple checked before assembly with attention to hygiene . ( correctly??)
2.Set throttle cable,
3.Idling adjustment was not making a difference which leads me looking again at the fast idle setting. I can't see how the fast idle adjusting screw was influencing the 0.54-0.55 mm clearance between the idle adjusting sure and the lever Page 50 Fig. E20and E21
4.The Balance adjusting stews have been initially seat 2.5 turns out as a starting point before synchronising.
5.New spark plugs
6. Checked cam clearances. OK
I would be just guessing from here on in so if anyone could through some light what I am doing wrong, that would be greatly appreciated.

Thanks Bill

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uncontrolled revving 2 weeks 6 days ago #26803

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Bill, hi
Million to one chance, but i had a similar experience with my Z13 after going thru a thorough set up process - the bike was text book set correctly but revved !
it drove me mad.

After many many hours of searching I found a 3mm piece of debris had broken off the inner twist grip throttle tube / cable carrier, and was effectively stopping the throttle return cable from fully closing, even though it appeared closed at the twist grip. Once removed the bike was spot on - that little piece of debris caused me so much pain.

Cheers Tim
"Success consists of going from failure to failure without the loss of enthusiasm " Winston Churchill.

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uncontrolled revving 2 weeks 6 days ago #26804

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Are you 100% confident your sync is definitley correct ?
Do all 3 adjusters look very similar in height / setting ?
Do any of them feel tighter than the other 2 ?
I cannot understand how you set them if the revs go upto 4k when you run the engine ???
Start your mixture setings at 3.5 turns out and go from there............and always use a Colortune Plug to set them if you have one.

Pete F
UK
The Older I Get........The Better I Was !

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uncontrolled revving 2 weeks 6 days ago #26806

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You should start by getting the carbs on your bench! With the Choke OFF, check the throttle plate gap by shining a light through one end of each carb. There should be only a sliver of light. The throttle plates should be open only enough to have a 1/2" wide strip of Printer Paper (placed between the top or bottom of the plate and the venturi) to have some resistance when trying to remove this strip. The 3 adjusters will need to be loosened at first and then carefully screwed in to achieve some drag on the removal of the paper strip. This is an arbitrary static sync. setting ! THEN, follow the manual for the Fast Idle adjustment. The fast idle adjustment is simply to give additional throttle plate opening (air) when the fast idle roller is on the highest point of the fast idle Cam. This provides additional air when the choke plungers are open for starting. Then the idle "knob" ( between # 1 and #2 carbs) can be adjusted to achieve that .55 mm gap you refer to. In my experience this is also an arbitrary setting, because our bikes/carbs/linkages are old, and wear plays a significant part in the fine tuning.
I also find it difficult to understand how you sync'd if the engine runs at 4k RPM! A point of concern is you stating you started your Sync. with the 3 adjusters at 2.5 turns out ? The manual recommends 1.5 as the starting point ! Regardless; you may have inadvertently ended up with one or more of these 3 sync. adjusters screwed in too tight. This will cause binding and result in the high RPM. @ "idle" because the throttle plates can't close properly due to the friction of an over tightened adjuster. Same as having some throttle applied. When the choke is OFF, there should be only several thou. gap between the fast idle cam and the roller. This ensures the choke plungers can close fully.
Going to start here by ending this here, to avoid rewriting the manual and hope it brings something to your attention, with regard to your carbs.
1980 KZ 1300 sr# KZT30A-009997
Always High - Know Fear !

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Last edit: by Kawboy.

uncontrolled revving 2 weeks 4 days ago #26826

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Thanks Tim, I did have a look at the cable and was nice and smooth...so not that.

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uncontrolled revving 2 weeks 4 days ago #26827

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Thanks Pete,Just clarifying the sync. I did not attempt to sync at those revs...it was a starting point that I was going to use but when the revs went high I did not proceed.
I have the fuel air mix set as suggested and I do have a colortune and a synchroniser as well.I will get to the air fuel mix soon.

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