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Replaced perished manifold boots now v high idle speed
- Jimbo68
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04 Mar 2023 10:07 - 04 Mar 2023 14:38 #881096
by Jimbo68
1981 Kawasaki KZ440-A2
Replaced perished manifold boots now v high idle speed was created by Jimbo68
On the advice of a Kawasaki engineer I replaced the manifold carburettor boots.
notwithstanding the difficulty in both removing and replacing the carbs, the idle speed is now over 5000rpm. The engineer warned me this would happen however loosening the black thumb-grip idle adjuster screw underneath the carbs right off, the high rpm remains.
prior to the removal of the carbs, it idled around 700 rpm.
the engine certainly runs better in gear but Boy! After one mile the exhausts were red hot.
there is no slack on the throttle. As soon as I begin to turn it, it revs. At the very least I need to introduce some short slack there.
im now having a brain freeze. To reduce the idle speed, do I need to adjust the throttle cable adjuster to effectively make the outer cable longer, or shorter? There is very little room to make it shorter.
I am loathed to remove the carbs again. The gap between the engine block and the plastic air box behind is so much narrower than the width of the carbs with the manifold boots on. I followed the service manual instructions to the letter and it was brute force to both remove and replace the carbs.
advice gratefully received.
notwithstanding the difficulty in both removing and replacing the carbs, the idle speed is now over 5000rpm. The engineer warned me this would happen however loosening the black thumb-grip idle adjuster screw underneath the carbs right off, the high rpm remains.
prior to the removal of the carbs, it idled around 700 rpm.
the engine certainly runs better in gear but Boy! After one mile the exhausts were red hot.
there is no slack on the throttle. As soon as I begin to turn it, it revs. At the very least I need to introduce some short slack there.
im now having a brain freeze. To reduce the idle speed, do I need to adjust the throttle cable adjuster to effectively make the outer cable longer, or shorter? There is very little room to make it shorter.
I am loathed to remove the carbs again. The gap between the engine block and the plastic air box behind is so much narrower than the width of the carbs with the manifold boots on. I followed the service manual instructions to the letter and it was brute force to both remove and replace the carbs.
advice gratefully received.
1981 Kawasaki KZ440-A2
Last edit: 04 Mar 2023 14:38 by SWest.
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- Scirocco
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04 Mar 2023 10:53 - 04 Mar 2023 15:41 #881097
by Scirocco
My 1975 Z 1 B 900 Project
www.kzrider.com/forum/11-projects/605133...ears-deep-sleep-mode
Replied by Scirocco on topic Replaced perished manifold boots now v high idle speed
First at all your throttle cable and RH control switsh wiring looks like under permanent tention (higher/wider handle bar).
Do you have any slack or play in throttle grip, if not adjust the cable adjuster screw if possible?
It could be a sharp bent, knick or rust build up that stiffen the cable movment. A good cleaning and some drops of oil on all moving parts do sometimes wonderful thinks!
I don´t see any hose clamps on the airbox to carb and carb to intake boots side! So your engine is runing lean and hot!
After this the carbs need also a static/vaccum sync to balance the the carbs butterflys to the same amount of air/fuel for a smooth idle.
Do you have any slack or play in throttle grip, if not adjust the cable adjuster screw if possible?
It could be a sharp bent, knick or rust build up that stiffen the cable movment. A good cleaning and some drops of oil on all moving parts do sometimes wonderful thinks!
I don´t see any hose clamps on the airbox to carb and carb to intake boots side! So your engine is runing lean and hot!
After this the carbs need also a static/vaccum sync to balance the the carbs butterflys to the same amount of air/fuel for a smooth idle.
My 1975 Z 1 B 900 Project
www.kzrider.com/forum/11-projects/605133...ears-deep-sleep-mode
Last edit: 04 Mar 2023 15:41 by Scirocco.
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04 Mar 2023 12:02 #881099
by Jimbo68
1981 Kawasaki KZ440-A2
Replied by Jimbo68 on topic Replaced perished manifold boots now v high idle speed
I’ll check the slack on the throttle cable.
there was never a spring band on the air box side of the carb. The clamps I removed from the intake boots were huge. I’ll order replacements. The fit without the clamps is better than the perished originals.
I have no slack on the throttle grip.
Which way should I be adjusting the cable adjuster screw? This is where the brain freeze has set in! In one of the pictures you can see the majority of the outer cable thread is below the bracket. Should there be less of that thread, I.e. effectively making the outer cable longer, to reduce the idle speed?
there was never a spring band on the air box side of the carb. The clamps I removed from the intake boots were huge. I’ll order replacements. The fit without the clamps is better than the perished originals.
I have no slack on the throttle grip.
Which way should I be adjusting the cable adjuster screw? This is where the brain freeze has set in! In one of the pictures you can see the majority of the outer cable thread is below the bracket. Should there be less of that thread, I.e. effectively making the outer cable longer, to reduce the idle speed?
1981 Kawasaki KZ440-A2
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04 Mar 2023 12:38 - 04 Mar 2023 14:42 #881100
by Warren3200gt
Replied by Warren3200gt on topic Replaced perished manifold boots now v high idle speed
Airbox side spring clips are not as important as engine side manifold clamps. Without the engine side clamps you'll be drawing in unmonitored air and running lean.
Throttle cable outer, shorter means longer usable inner so allowing slides to close fully.
Read the service manual section about routing and fitting the cables and how much slack each cable should have when the throttle is fully closed.
If you don't have a service manual you can download one from the files section of this forum.
Throttle cable outer, shorter means longer usable inner so allowing slides to close fully.
Read the service manual section about routing and fitting the cables and how much slack each cable should have when the throttle is fully closed.
If you don't have a service manual you can download one from the files section of this forum.
Last edit: 04 Mar 2023 14:42 by Warren3200gt.
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- Mikaw
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04 Mar 2023 14:31 #881109
by Mikaw
1976 KZ 900 A4 kzrider.com/forum/11-projects/613548-1976-kz-900-a4
1976 KZ 900 B1 LTD
1978 KZ 1000 B2 LTD
1980 KZ 750 E1
Kowledge Speaks, But Wisdom Listens.
Jimi Hendrix.
Replied by Mikaw on topic Replaced perished manifold boots now v high idle speed
Might wanna find a new mechanic. I have never heard of it being normal for RPM to increase by 4,300 RPM just because you replaced carb manifold/hanger rubbers. As for the cable, you can not change the length of the Inner cable, it’s fixed by the Ferrules. You adjust cable play by turning the adjusters on the outer sheath. At the carb, loosen the lock nuts, turn the adjuster clockwise to increase slack. Counter clockwise to decrease. The twist grip should have a small amount 1/8” to 1/4” of slack to be correct.
1976 KZ 900 A4 kzrider.com/forum/11-projects/613548-1976-kz-900-a4
1976 KZ 900 B1 LTD
1978 KZ 1000 B2 LTD
1980 KZ 750 E1
Kowledge Speaks, But Wisdom Listens.
Jimi Hendrix.
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- SWest
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04 Mar 2023 14:47 #881110
by SWest
Replied by SWest on topic Replaced perished manifold boots now v high idle speed
I fixed your pics. Next time click insert all after your text. Not having clamps on the intakes will cause a lean condition. Also lubing the cables can be your friend.
Steve
Steve
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04 Mar 2023 17:05 #881112
by Jimbo68
1981 Kawasaki KZ440-A2
Replied by Jimbo68 on topic Replaced perished manifold boots now v high idle speed
This problem is keeping me awake
there is very limited scope to turn the adjuster clockwise. See the picture. I don’t think I’ll get the revs down much with what’s left of the threads, so there must be something else going on. Do you agree?
I’ve ordered replacement clamps for the boots. Due in a few days. Again, given how perished the old ones were, will the clamps reduce the idle speed massively?
I do think I have an issue with the throttle cable route. It is now stretched when I turn the handlebars full left. It wasn’t before. It’s ok with the handlebars straight, and turned right Looking at old pictures, it should be routing through a gap near the top of the petrol tank. It’s currently routing much lower. I’ll fix that tomorrow am if I can.
can you confirm, turning the thumb wheel idle adjustment screw clockwise INCREASES rpm?
tbf, the engineer didn’t say the rpm would reach 5000rpm. He said it would increase quite a bit and would need adjusting.
there is very limited scope to turn the adjuster clockwise. See the picture. I don’t think I’ll get the revs down much with what’s left of the threads, so there must be something else going on. Do you agree?
I’ve ordered replacement clamps for the boots. Due in a few days. Again, given how perished the old ones were, will the clamps reduce the idle speed massively?
I do think I have an issue with the throttle cable route. It is now stretched when I turn the handlebars full left. It wasn’t before. It’s ok with the handlebars straight, and turned right Looking at old pictures, it should be routing through a gap near the top of the petrol tank. It’s currently routing much lower. I’ll fix that tomorrow am if I can.
can you confirm, turning the thumb wheel idle adjustment screw clockwise INCREASES rpm?
tbf, the engineer didn’t say the rpm would reach 5000rpm. He said it would increase quite a bit and would need adjusting.
1981 Kawasaki KZ440-A2
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04 Mar 2023 17:08 #881113
by Jimbo68
1981 Kawasaki KZ440-A2
Replied by Jimbo68 on topic Replaced perished manifold boots now v high idle speed
Thanks.
I clicked “attachments “ to attach the pictures. Is there another button I should press instead?
I clicked “attachments “ to attach the pictures. Is there another button I should press instead?
1981 Kawasaki KZ440-A2
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04 Mar 2023 17:30 #881114
by Nessism
Regarding the problem, there is something wrong with your throttle cable. Most likely it's not seated somewhere.
Replied by Nessism on topic Replaced perished manifold boots now v high idle speed
As Steve mentioned, you need to click "insert all", to place the photos into your post.Thanks.
I clicked “attachments “ to attach the pictures. Is there another button I should press instead?
Regarding the problem, there is something wrong with your throttle cable. Most likely it's not seated somewhere.
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05 Mar 2023 01:13 #881125
by Jimbo68
1981 Kawasaki KZ440-A2
Replied by Jimbo68 on topic Replaced perished manifold boots now v high idle speed
I’ve removed the tank and the routing of the cable wasn’t perfect. No kink but perhaps the tank was pressing on the outer sheath.
can someone please tell me, does the idle screw INCREASE the tickover when turning clockwise? I’d like to know this before I start it back up again.
thanks for all the advice so far. Much appreciated. I’m doing this carb stuff for the first time so everything is new to me. I have the correct service manual but it doesn’t help as much you folks
can someone please tell me, does the idle screw INCREASE the tickover when turning clockwise? I’d like to know this before I start it back up again.
thanks for all the advice so far. Much appreciated. I’m doing this carb stuff for the first time so everything is new to me. I have the correct service manual but it doesn’t help as much you folks
1981 Kawasaki KZ440-A2
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05 Mar 2023 01:18 #881126
by kevski
Replied by kevski on topic Replaced perished manifold boots now v high idle speed
Clockwise increases idle speed.
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05 Mar 2023 03:16 #881127
by Jimbo68
1981 Kawasaki KZ440-A2
Replied by Jimbo68 on topic Replaced perished manifold boots now v high idle speed
Cable now sorted. I’ve given about 1/8” slack. I’ve attached a video.
I’ve adjusted the tickover and it sits nicely between 1100 and 1300. A short run after it was warmed up and the choke fully down and it is running sweeter then ever.
BUT ….. The rhs carb overflow is leaking a stream of petrol. This was not happening before. The fuel switch is at ON.
I thought I’d made such great progress with this forum’s help.
What might be the problem now please?
I’ve adjusted the tickover and it sits nicely between 1100 and 1300. A short run after it was warmed up and the choke fully down and it is running sweeter then ever.
BUT ….. The rhs carb overflow is leaking a stream of petrol. This was not happening before. The fuel switch is at ON.
I thought I’d made such great progress with this forum’s help.
What might be the problem now please?
1981 Kawasaki KZ440-A2
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