User Tag List

Page 1 of 2 12 LastLast
Results 1 to 15 of 16

Thread: Still no vacuum fon # 3 and #4

  1. #1
    Join Date
    Jan 2008
    Location
    Herndon
    Posts
    142
    United States
    VA
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default Still no vacuum fon # 3 and #4

    I thought I had cylinder #1 not firing because it was cold. I pulled the plug and turned the bike over and there was spark. As I went to pull #1 plug it was completely loose. Checked all the rest they were loose also. Thought that might be the reason for no vacuum. Tightened them all up and put things back together but still no vacuum form 3 and 4. I pulled the carbs off. Checking the vacuum pistons #3 springs back really quickly all three of the others are real sluggish. Could that have any thing do do with the no vacuum on #3 and 4? I'm going to check the jets next to see if any are clogged. I'm about at my whits end! I was really hoping to get things straightened out before the WNY rally.
    Kim Woodworth

  2. #2
    Join Date
    Aug 2006
    Location
    Greenville
    Posts
    1,097
    United States
    NC
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default Re: Still no vacuum fon # 3 and #4

    My guess would be that the throttle plates in carbs 3 &4 are more open than the ones in 1 & 2. A larger hole in the vacuum passage= less vacuum. If you still have the carbs off, measure the clearance of each throttle plate to carb throat. You can also shine a light from the bottom of carbs and see if one throttle plate is more open than the others.

    Earl

  3. #3
    Join Date
    Jul 2010
    Location
    Port Byron
    Posts
    1,800
    United States
    NY
    Post Thanks / Like
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)

    Default Re: Still no vacuum fon # 3 and #4

    No vacuum= broken piston rings, valve stuck open, blown head gasket, cracked head, hole in piston, bad seal between intake manifold and heads bad seal between carbs and intake manifold, broken vacuum lines or just not connected and probably a couple of things I have forgotten over the years.Now with that said, go back to before you pull carbs and set your valve clearance. did the bike run ok? If so then you know the problem has something to do with the reinstall of everything you removed. I still say the carbs on that side of the motor were not fully seated in the intake boots. the jets can be plugged, the carbs can be way out of sinc and you will still have vacuum. the problem is an air leak.
    if you can't have fun here, you can't have fun anywhere!

  4. #4
    Join Date
    Jul 2010
    Location
    Port Byron
    Posts
    1,800
    United States
    NY
    Post Thanks / Like
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)

    Default Re: Still no vacuum fon # 3 and #4

    When you say cylinders 3&4 I'm assuming you are referring to the cyl's on the left side of the bike? Keep in mind all 4 cyl's and all four carb's are separate from each other, so the only thing that can effect 2 cyl's at the same time has to be something that is common two both cyl's, that can only be the intake boots or a common vacuum line.
    if you can't have fun here, you can't have fun anywhere!

  5. #5
    Join Date
    Aug 2006
    Location
    Brantford
    Posts
    8,097
    Canada
    ON
    Post Thanks / Like
    Mentioned
    46 Post(s)
    Tagged
    0 Thread(s)

    Default Re: Still no vacuum fon # 3 and #4

    Quote Originally Posted by steamer View Post
    When you say cylinders 3&4 I'm assuming you are referring to the cyl's on the left side of the bike? Keep in mind all 4 cyl's and all four carb's are separate from each other, so the only thing that can effect 2 cyl's at the same time has to be something that is common two both cyl's, that can only be the intake boots or a common vacuum line.
    As you sit on the bike, 3&4 are on the right side. Now which ones exactly are the issue, it makes a difference on the diagnosis.
    It's nice to be the same
    But
    It's great to be different!

  6. Thanks cowpuc gave thanks for this post
    Likes cowpuc liked this post
  7. #6
    Join Date
    Mar 2007
    Location
    North Muskegon
    Posts
    15,792
    United States
    MI
    Post Thanks / Like
    Mentioned
    422 Post(s)
    Tagged
    0 Thread(s)

    Default Re: Still no vacuum fon # 3 and #4

    I'd check the compression on each jug with a compression gauge long before I started rippin er down to rebuild er because of vac loss if it were mine.. A cracked hose or two or a line off somewhere can cause a complete loss of vacuum really easily... Wonder if somehow the screw that controls the sync match between 3/4 and 1/2 somehow got screwed in and its holding the throttle plates open on the right side.. That make sense,,, probably not,,, worth asking about though I guess so I will leave it on here..
    Kretz = An explanation about all that time flying by? When you were a young scallywag, say 6 years old; one year was a 6th of your lifetime. Now at 60; one year is a 60th of your lifespan & so seems to whiz by in a blink of the proverbial eye. Ten times as fast as when you were that little kid!

  8. Likes mm482 liked this post
  9. #7
    Join Date
    Jul 2016
    Location
    Joplin
    Posts
    2,625
    United States
    MO
    Post Thanks / Like
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)

    Default Re: Still no vacuum fon # 3 and #4

    Quote Originally Posted by cowpuc View Post
    I'd check the compression on each jug with a compression gauge long before I started rippin er down to rebuild er because of vac loss if it were mine.. A cracked hose or two or a line off somewhere can cause a complete loss of vacuum really easily... Wonder if somehow the screw that controls the sync match between 3/4 and 1/2 somehow got screwed in and its holding the throttle plates open on the right side.. That make sense,,, probably not,,, worth asking about though I guess so I will leave it on here..
    Um it makes alot of sense to me as I barely had vacuum on one side and had to back the screw out to start getting vaccuum on the one side but anyways I am tired.... May be talking in circles, But do you just take Cat naps there Clark?

  10. Likes mm482 liked this post
  11. #8
    Join Date
    Mar 2007
    Location
    North Muskegon
    Posts
    15,792
    United States
    MI
    Post Thanks / Like
    Mentioned
    422 Post(s)
    Tagged
    0 Thread(s)

    Default Re: Still no vacuum fon # 3 and #4

    Quote Originally Posted by snyper316 View Post
    Um it makes alot of sense to me as I barely had vacuum on one side and had to back the screw out to start getting vaccuum on the one side but anyways I am tired.... May be talking in circles, But do you just take Cat naps there Clark?
    Yep,, they grabbed a bunch of my bladder when they yanked the cancer out me back in January and now I am a 2 oz pee er.. Not so bad but gotta get up frequently to go pee pee - not that much fun but better then pushin up daisies and not being able to give you guys a hard time
    Kretz = An explanation about all that time flying by? When you were a young scallywag, say 6 years old; one year was a 6th of your lifetime. Now at 60; one year is a 60th of your lifespan & so seems to whiz by in a blink of the proverbial eye. Ten times as fast as when you were that little kid!

  12. Likes snyper316 liked this post
  13. #9
    Join Date
    Jan 2008
    Location
    Herndon
    Posts
    142
    United States
    VA
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default Re: Still no vacuum fon # 3 and #4

    Sitting on the bike the right side 2 cylinders. I pulled the carbs and #3 and 4 butterfly were sightly open @1 and 2 were completely closed. Turning the sync screws I got all 4 completely closed. I'll check the vacuum lines and see if I see any cracks and make sure I have everything back together correctly. Is there a special compression tool for our bikes. The spark plug holes are so far in, it seems you would need a compression gauge just for the second gen cylinders. One more question. Setting the float levels was supposed to improve the gas mileage. Was that due to setting the floats to close sooner so less gas gets in the chamber?
    Kim Woodworth

  14. Likes mm482 liked this post
  15. #10
    Join Date
    Jul 2010
    Location
    Port Byron
    Posts
    1,800
    United States
    NY
    Post Thanks / Like
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)

    Default Re: Still no vacuum fon # 3 and #4

    Quote Originally Posted by Marcarl View Post
    As you sit on the bike, 3&4 are on the right side. Now which ones exactly are the issue, it makes a difference on the diagnosis.
    Right, now I remember, #1 is the left rear cyl.
    if you can't have fun here, you can't have fun anywhere!

  16. #11
    Join Date
    Jan 2009
    Location
    Bessemer City, NC
    Posts
    2,366
    United States
    NC
    Post Thanks / Like
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)

    Default Re: Still no vacuum fon # 3 and #4

    You need to sync the carbs after messing with the screws. I had no vacuum on 3&4 after rebuilding the carbs and syncing them brought all back in line.



    Quote Originally Posted by KAWoodworth View Post
    Sitting on the bike the right side 2 cylinders. I pulled the carbs and #3 and 4 butterfly were sightly open @1 and 2 were completely closed. Turning the sync screws I got all 4 completely closed. I'll check the vacuum lines and see if I see any cracks and make sure I have everything back together correctly. Is there a special compression tool for our bikes. The spark plug holes are so far in, it seems you would need a compression gauge just for the second gen cylinders. One more question. Setting the float levels was supposed to improve the gas mileage. Was that due to setting the floats to close sooner so less gas gets in the chamber?
    Jim aka Sylvester
    Where did all the years go? I think I slept through the last twenty.


  17. Likes mm482 liked this post
  18. #12
    Join Date
    Jul 2016
    Location
    Youngstown
    Posts
    245
    United States
    OH
    Post Thanks / Like
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)

    Default Re: Still no vacuum fon # 3 and #4

    At this point, you should run a compression test, bench sync the carbs and check and recheck all the rubber bits and hoses for cracks and proper connection.

    The Harbor Freight compression tester is good enough to find any major issue and should reach all four cylinders.
    TAANSTAAFL

  19. #13
    Join Date
    Aug 2006
    Location
    Brantford
    Posts
    8,097
    Canada
    ON
    Post Thanks / Like
    Mentioned
    46 Post(s)
    Tagged
    0 Thread(s)

    Default Re: Still no vacuum fon # 3 and #4

    Keep it simple, start with the sync. Sounds to me that would be the major if not all of your problem. You will need a proper gauge though, it can't be done by ear, I mean, it can't be done by ear, which means that listening to it won't get you very far, you'll need eyes to do it even close to right.
    It's nice to be the same
    But
    It's great to be different!

  20. #14
    Join Date
    Jan 2009
    Location
    Bessemer City, NC
    Posts
    2,366
    United States
    NC
    Post Thanks / Like
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)

    Default Re: Still no vacuum fon # 3 and #4

    I will loan you my Carb Tune if you need one.

    Jim aka Sylvester
    Where did all the years go? I think I slept through the last twenty.


  21. #15
    Join Date
    Jan 2008
    Location
    Herndon
    Posts
    142
    United States
    VA
    Post Thanks / Like
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Default Re: Still no vacuum fon # 3 and #4

    Thanks guys. After fooling with carb sync I finally got vacuum out of #3 and 4. #3 is much higher than 4 but I could not get them to match. #1 and 2 seem to be just fine. I'll try some more after work today. I added some Tecron fuel cleaner and hope that it would help #4 . Maybe something gummed up.
    Kim Woodworth

Page 1 of 2 12 LastLast

Similar Threads

  1. Almost no vacuum
    By KAWoodworth in forum Watering Hole
    Replies: 10
    Last Post: 08-09-2017, 05:03 PM
  2. Vacuum sensor hold a vacuum?
    By Peder_y2k in forum First Generation Venture Tech Talk ('83 - '93)
    Replies: 15
    Last Post: 09-14-2012, 03:24 AM
  3. Vacuum Actuator
    By Bill W. in forum First Generation Venture Tech Talk ('83 - '93)
    Replies: 1
    Last Post: 03-22-2010, 11:37 AM
  4. How much Vacuum?
    By concord006 in forum First Generation Venture Tech Talk ('83 - '93)
    Replies: 14
    Last Post: 03-03-2010, 01:43 PM
  5. too much vacuum
    By tenglin in forum Second Generation Venture Tech Talk ('99 - '13)
    Replies: 4
    Last Post: 03-01-2008, 08:03 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •