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petcock stuck on vacuum
- aenikolopov
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23 Aug 2015 18:15 #686901
by aenikolopov
petcock stuck on vacuum was created by aenikolopov
Hi all, I know much has been written about petcocks here, but I can't find something on quite this issue.
I have a 1980 KZ650 F1, with the auto vacuum petcock. It has been leaking gas. I opened the back of it up, and the diaphragm was sucked in, letting the gas flow through, as though there was a vacuum being applied on the vacuum port, though there was not. I guess the vacuum inlet was clogged up, or the check-valve that is in the vacuum inlet was clogged. I cleaned out that vacuum inlet with carb cleaner, reassembled it and it seemed to work perfectly fine. A couple days later it was leaking again. Opened it up, didn't do anything, put it back together and it worked again. Does anyone have an idea of what is going on here? I can get a rebuild kit, sure, but I don't think that addresses what's going on here. Maybe I just need to clean out the vacuum inlet again? I thought I had sprayed the hell out of it with carb cleaner. I don't quite understand why there is a check valve in there anyway.
I have a 1980 KZ650 F1, with the auto vacuum petcock. It has been leaking gas. I opened the back of it up, and the diaphragm was sucked in, letting the gas flow through, as though there was a vacuum being applied on the vacuum port, though there was not. I guess the vacuum inlet was clogged up, or the check-valve that is in the vacuum inlet was clogged. I cleaned out that vacuum inlet with carb cleaner, reassembled it and it seemed to work perfectly fine. A couple days later it was leaking again. Opened it up, didn't do anything, put it back together and it worked again. Does anyone have an idea of what is going on here? I can get a rebuild kit, sure, but I don't think that addresses what's going on here. Maybe I just need to clean out the vacuum inlet again? I thought I had sprayed the hell out of it with carb cleaner. I don't quite understand why there is a check valve in there anyway.
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- SWest
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- 10 22 2014
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23 Aug 2015 19:01 #686908
by SWest
Replied by SWest on topic petcock stuck on vacuum
Your manual will show you if you have one.
Steve
Steve
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- aenikolopov
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23 Aug 2015 19:30 #686920
by aenikolopov
Replied by aenikolopov on topic petcock stuck on vacuum
Yep, definitely have a vacuum petcock, thanks. Thoughts as to why it's getting stuck in the sucked-in state?
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- SWest
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23 Aug 2015 21:08 #686929
by SWest
Replied by SWest on topic petcock stuck on vacuum
There should be a spring in there. I was suggesting the manual would have a diagram of it.
Steve
Steve
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- aenikolopov
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23 Aug 2015 21:40 #686935
by aenikolopov
Replied by aenikolopov on topic petcock stuck on vacuum
Ah, right. Yes, mine has a spring. I stretched it out some, though even before that, it did seem to work fine after I relieved the vacuum by taking the diaphragm off and then reassembling it.
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- SWest
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23 Aug 2015 21:49 #686937
by SWest
Replied by SWest on topic petcock stuck on vacuum
You shouldn't stretch a spring. The vacuum shouldn't be there with the engine off. You really do need to get a manual.
Steve
Steve
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- bluej58
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24 Aug 2015 04:37 #686945
by bluej58
78 KZ1000 A2A
Replied by bluej58 on topic petcock stuck on vacuum
No eBay APP ID and/or Cert ID defined in Kunena configurationOver time the modern fuel with 10% alcohol eats away at the rubber parts in your petcock, the round part that has the 5 holes is the one that usually screws up on mine, it's the gasket that goes behind the selector lever.
My advise to you is buy the kit and be done with it .... for now.
My advise to you is buy the kit and be done with it .... for now.
78 KZ1000 A2A
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- SWest
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24 Aug 2015 06:25 #686958
by SWest
Replied by SWest on topic petcock stuck on vacuum
:whistle:
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- TexasKZ
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24 Aug 2015 14:04 #687011
by TexasKZ
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough
Replied by TexasKZ on topic petcock stuck on vacuum
Might be the small o-ring seal on the post in the middle of the diaphragm. If it has a rough spot or has softened due to contact with fuel, it can stick. Be careful about the cleaner you use, some of them attack rubber.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough
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- LineArtist
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24 Aug 2015 14:24 - 24 Aug 2015 14:46 #687013
by LineArtist
'79 KZ650B3 (stock)
'79 KZ650B3 (parts bike)
'06 HD 883R
Replied by LineArtist on topic petcock stuck on vacuum
80 650 F1 - petcock parts
check to make sure the diaphragm and all other parts are in the correct orientation (check for gas hole to correspond with the other parts) - may just be staying open because it can't find air to snap back.
I rebuilt mine last year (slightly different than yours, but still vacuum style). These are the parts, alignment is necessary for the PC to function properly. Take note of the small plastic pins on the part to the right.
check to make sure the diaphragm and all other parts are in the correct orientation (check for gas hole to correspond with the other parts) - may just be staying open because it can't find air to snap back.
Attachment Capture-2.jpg not found
I rebuilt mine last year (slightly different than yours, but still vacuum style). These are the parts, alignment is necessary for the PC to function properly. Take note of the small plastic pins on the part to the right.
Attachment IMG_3025.jpg not found
'79 KZ650B3 (stock)
'79 KZ650B3 (parts bike)
'06 HD 883R
Attachments:
Last edit: 24 Aug 2015 14:46 by LineArtist.
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- RonKZ650
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25 Aug 2015 20:32 #687148
by RonKZ650
321,000 miles on KZ's that I can remember. Not going to see any more.
Replied by RonKZ650 on topic petcock stuck on vacuum
I've fought this a couple times over the years, and being a mechanical kind of guy, I was not going to let this simple system get the best of me, but it did. What I found was the diaphram, spring, oring ect. All of it may look fine, you can clean, lube and otherwise spend effort for hours, and all for nothing. Buy a new diaphram and be done with it. I found the original Kawasaki diaphram was like $13.00 last time I did one. I never, ever had problems after replace of the diaphram. Others have reported no luck replacing the diaphram though, so mileage may vary, but it has always worked for me.
321,000 miles on KZ's that I can remember. Not going to see any more.
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- SWest
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25 Aug 2015 20:38 #687149
by SWest
Replied by SWest on topic petcock stuck on vacuum
They get hard and lose their elasticity. O ring should be replaced at the same time.
Steve
Steve
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