- Posts: 56
- Thank you received: 0
Vacuum petcock vs non vacuum
- mjkawa
- Topic Author
- Offline
- User
Both bikes have pretty similar setups, (4-1 pipes, and stock airbox) so will probably be jetted the same.
But the 78 has a petcock w/ the vacuum, and the 77 has a petcock w/o the vacuum.
Could I simply change the petcock on the 78 to one w/o the vacuum, and plug the vacuum line?? Or will this affect how the carbs perform??
I know that I could just switch the tanks and petcocks with the carbs, but if I can, I would like to make it as easy as possible to switch back and forth.
Thanks for any ideas.
MJ
82 KZ-1000-J
77 KZ650 B
Please Log in or Create an account to join the conversation.
- TeK9iNe
- Offline
- User
- What did you do!?!
- Posts: 2440
- Thank you received: 28
I don't mind turning my fuel on and off.
Motorcycle Shop Owner/Operator
79 Kawie Z1000 LTD
81 Kawie Z1000 CSR
83 Honda VT750C A
85 Kawie GPZ900 A2
86 Zukie GS1150 EG
93 Yamie XV1100 E
Lucky to have rolled many old bikes through my doors
Please Log in or Create an account to join the conversation.
- Patton
- Offline
- KZr Legend
- Posts: 18640
- Thank you received: 2098
Where vacuum petcock replaces manual petcock, just add vacuum hose from any vacuum nipple to the vacuum petcock.
Good Luck!
1973 Z1
KZ900 LTD
Please Log in or Create an account to join the conversation.
- deftones5792
- Offline
- User
- Posts: 6
- Thank you received: 0
Ryan
Please Log in or Create an account to join the conversation.
- RonKZ650
- Offline
- User
- Posts: 3703
- Thank you received: 240
321,000 miles on KZ's that I can remember. Not going to see any more.
Please Log in or Create an account to join the conversation.
- JMKZHI
- Offline
- Platinum Member
- Posts: 2429
- Thank you received: 48
By any chance do you know what brand of rebuild kit the po installed? Some are made in China. Others are made in Japan.... I bought a 1980 KZ550LTD ... the petcock leaks. The previous owner installed the rebuild kit but it did not fiz the problem. I have ordered a replacement manual petcock and adapter plate from z1enterprises.com. ...
Install a good vacuum cap from the auto parts store - they usually come in packages of 4 or 5. The aftermarket fuel valve screen may not fit into the tank's opening. If you decide to ream out the hole a tad, keep in mind that it's a fuel tank & a spark could cause an explosion.
Please Log in or Create an account to join the conversation.
- Patton
- Offline
- KZr Legend
- Posts: 18640
- Thank you received: 2098
Plugging the line is simple, just find something to stuff in there. A piece of wood dowell, old screw in appropriate size ect. Anything the basic diameter of the hose can be used to plug it. Not plugging the line will cause a vacuum leak and it won't idle right, no other big deal. I doubt holing a piston has ever happened from a vacuum line on a KZ.
Correct.
As also noted, one option is to simply cap off the now unused vacuum nipple at the carbs.
Another vacuum plug just like the others should do just fine.
The high quality set from Z1E comes with 5 plugs.
Click here > Z1E Vacuum Plugs
Good Luck!
1973 Z1
KZ900 LTD
Please Log in or Create an account to join the conversation.
- YUKABODOS
- Offline
- User
- Posts: 103
- Thank you received: 0
I would much rather have the vacume operated petcock. Easy to forget to turn off the gas. Plus swapping over the tanks takes all of 2 mins (1 for each tank) I would just swap carbs and tanks. Christ, if you can work on carbs then you can swap tanks.
Please Log in or Create an account to join the conversation.
- deftones5792
- Offline
- User
- Posts: 6
- Thank you received: 0
Please Log in or Create an account to join the conversation.
- chance
- Offline
- User
- Life long biker/
- Posts: 583
- Thank you received: 0
Correct ..Your bike will perform as well with either petcock you use ..Patton has the easy swap for you.Should be easy to simply cap off the vacuum nipple not needed for manual petcock.
Where vacuum petcock replaces manual petcock, just add vacuum hose from any vacuum nipple to the vacuum petcock.
Good Luck!
Please Log in or Create an account to join the conversation.
- bluej58
- Offline
- Sustaining Member
- The chrome don't get you home
- Posts: 2484
- Thank you received: 511
Where vacuum petcock replaces manual petcock, just add vacuum hose from any vacuum nipple to the vacuum petcock.
On the kz900 carb are the nipples on the 1 and 4 carbs considered vacuum ?
78 KZ1000 A2A
Please Log in or Create an account to join the conversation.
- Patton
- Offline
- KZr Legend
- Posts: 18640
- Thank you received: 2098
Patton wrote:
Where vacuum petcock replaces manual petcock, just add vacuum hose from any vacuum nipple to the vacuum petcock.
On the kz900 carb are the nipples on the 1 and 4 carbs considered vacuum ?
The 1976 LTD carbs have 4 vacuum nipples, one on each carb holder. (Not shown in the above pic.)
The vacuum nipples are used when syncing the carbs.
During normal engine operation, all four nipples are sealed with a rubber cap on each nipple.
The 1976 LTD was fitted with a manual petcock from the factory. The manual petcock doesn't have a vacuum nipple.
A vacuum petcock does have a vacuum nipple to receive vacuum which operates the petcock.
Where the manual petcock is replaced with a vacuum petcock, any one of the vacuum nipples may be then used for supplying vacuum through a vacuum hose connected between it and the petcock vacuum nipple.
In the above image, may be looking at one of the two carb floatbowl vent nipples, which usually have hoses attached that exit to open air.
Here's a pic of the 1976 LTD carb with a blue arrow pointing to the rubber cap on the vacuum nipple located on the #4 carb holder.
Can also see the two yellow hoses from the vent nipples (which hoses exit to open air underneath the seat).
Good Luck!
[Click image to enlarge view]
1973 Z1
KZ900 LTD
Please Log in or Create an account to join the conversation.