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Slow throttle return
- Richie7
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1976 Kawasaki KZ900 A4
Carbs:
Mikuni 26mm with K&N oval filters(Main-120, Pilot-22.5, Needle clip-in the middle) Cleaned, rebuilt with new parts and lubed.
Problem:
Slow throttle return WHEN THE ENGINE IS RUNNING. Snaps right back when the engine is not running.
I can visually confirm that the throttle pulley slowly returns when it just hits the idle adjuster. The symptom is more obvious when I blip the throttle just a hair touch. All the linkages have been cleaned and lubed. I replaced the return spring. I checked all the places that relate to the linkage system, but no luck. The only thing I can think of is the throttle valves being worn out causing escaped air between the valves and carb bodies. Is this possible? I appreciate all your advises.
UPDATE: I took off push&pull cables to see how the linkage works without. Pulley moves freely without engine running. When the engine is running, I can definitely feel resistance at the lowest point with my finger. After passing that point, the pulley moves freely. Same thing coming back to the lowest point. I have to push the pulley to completely seat the slides.
1976 KZ900A4
98 CBR900RR Front End
01 GSXR1000 Swingarm + Wheel
Wiseco 1015cc Piston Kit
Dyna ignition + Accell Coils
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- Kidkawie
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- I bleed premix
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If it does, adjust the pull cable for normal operation. Then gradually adjust the push cable, once the action becomes slow, back off the push cable adjuster and lock it down.
1975 Z1 900
1994 KX250 Supermoto
2004 KX125
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- Kidkawie
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- I bleed premix
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1975 Z1 900
1994 KX250 Supermoto
2004 KX125
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- 650ed
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1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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- Richie7
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1976 KZ900A4
98 CBR900RR Front End
01 GSXR1000 Swingarm + Wheel
Wiseco 1015cc Piston Kit
Dyna ignition + Accell Coils
VM28 Pumpers
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- Richie7
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650ed wrote: Another thing to check is vacuum leaks at the carb holders. Test for leaks is described on this forum, but ask if you need instructions. Also, if you want to totally eliminate the possibility of hanging cables you can unhook them both at the carbs and see if the problem persists. If it does you can scratch cables off the possibilities list. Ed
1976 KZ900A4
98 CBR900RR Front End
01 GSXR1000 Swingarm + Wheel
Wiseco 1015cc Piston Kit
Dyna ignition + Accell Coils
VM28 Pumpers
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- Kidkawie
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- I bleed premix
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1975 Z1 900
1994 KX250 Supermoto
2004 KX125
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- zukdave
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if their worn and ruff on the intake side they will
drag and can act like your's.
1980 KZ650 F1
ZX750A1 motor.
Wiseco 810cc kit.
Zukiworks racing ported head.
VM 29 smooth bore's.
Dyna 2000 Ign. w/Dyna mini coil's
APE cylinder stud's and nut's.
APE valve spring's.
APE Track King clutch.
V/H KZ1000 sidewinder.
3.5x18 laced to a KZ1000 disk hub.
150/60/18 Shinko 006 Podium.
63" wheel base.
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- Richie7
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Kidkawie wrote: Do what Ed says and run it without the cables.
1976 KZ900A4
98 CBR900RR Front End
01 GSXR1000 Swingarm + Wheel
Wiseco 1015cc Piston Kit
Dyna ignition + Accell Coils
VM28 Pumpers
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- Richie7
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zukdave wrote: Vacuum will pull the slide towards the motor.
if their worn and ruff on the intake side they will
drag and can act like your's.
1976 KZ900A4
98 CBR900RR Front End
01 GSXR1000 Swingarm + Wheel
Wiseco 1015cc Piston Kit
Dyna ignition + Accell Coils
VM28 Pumpers
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- testarossa
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- Attack life, it's only trying to kill you.
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Richie7 wrote: Should I just go ahead and replace the slides or does that mean that the carb bodies might also be worn out?
zukdave wrote: Vacuum will pull the slide towards the motor.
if their worn and ruff on the intake side they will
drag and can act like your's.
Could also be varnish on the slides/carb bodies. It would be worth pulling the slides to clean and have a look. Just my .02 here so take it for what it's worth. If I needed new slides in a set of 26s I would be looking for a whole new set of carbs. IMO the 26s aren't worth the expense of new slides. Plus if the slides are that beat then the carb bodies can't be in very good shape themselves.
Edit: I see where you said the carbs were cleaned. Did you inspect the slides at the time?
1978 KZ1000 A2 Click--->Build Thread
2004 ZX-10R
2007 Harley Sportster 1200
2020 Harley Street Glide Special
Angola, IN
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- Richie7
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testarossa wrote:
Richie7 wrote: Should I just go ahead and replace the slides or does that mean that the carb bodies might also be worn out?
zukdave wrote: Vacuum will pull the slide towards the motor.
if their worn and ruff on the intake side they will
drag and can act like your's.
Could also be varnish on the slides/carb bodies. It would be worth pulling the slides to clean and have a look. Just my .02 here so take it for what it's worth. If I needed new slides in a set of 26s I would be looking for a whole new set of carbs. IMO the 26s aren't worth the expense of new slides. Plus if the slides are that beat then the carb bodies can't be in very good shape themselves.
Edit: I see where you said the carbs were cleaned. Did you inspect the slides at the time?
1976 KZ900A4
98 CBR900RR Front End
01 GSXR1000 Swingarm + Wheel
Wiseco 1015cc Piston Kit
Dyna ignition + Accell Coils
VM28 Pumpers
Please Log in or Create an account to join the conversation.