Technical Discussion Topics related to Technical Issues

carb sync

Old 10-06-2013, 01:24 PM
  #1  
Member
Squid
Thread Starter
 
Fistfullofthrotl718's Avatar
 
Join Date: Jul 2013
Location: Summerville, SC
Posts: 57
Fistfullofthrotl718 is on a distinguished road
carb sync

So I made one of the manometers. Like found on here (Thanks). I am unsure as to (after a search) find the answer Im looking for. After syncing at a slightly elevated idle, then hold the throttle to about 4-5k rpm, its pretty far off balance. is this normal? and if not, how to correct? i cant get idle and elevated rpms to match well. thanks.
Fistfullofthrotl718 is offline  
Old 10-06-2013, 02:34 PM
  #2  
Senior Member
Superstock
 
KCCO's Avatar
 
Join Date: Apr 2013
Location: SF Bay Area
Posts: 466
KCCO is on a distinguished road
I just re jetted and synced and find the same thing. At 1200 idle, the fluid in the tubes is even (very jumpy but even) adn when raping the throttle the front vaculme beceoms stronger. If I slowly roll on it goes back and forth until about 4k then the front raises a little. The bounciness goes away once some throttle is applied. I'm not sure if this helps at all but it's what my bike is doing.
KCCO is offline  
Old 10-06-2013, 03:16 PM
  #3  
Member
Squid
Thread Starter
 
Fistfullofthrotl718's Avatar
 
Join Date: Jul 2013
Location: Summerville, SC
Posts: 57
Fistfullofthrotl718 is on a distinguished road
I balanced it more even at close to 4k instead of idle. My mind says it would be better to have even pressure when Im getting into a load and less uneven as the rpms climb. Compared to setting them even at idle and be VERY far off as te rpms climb. Whats your thoughts on that?
Fistfullofthrotl718 is offline  
Old 10-06-2013, 03:37 PM
  #4  
Senior Member
Superstock
 
KCCO's Avatar
 
Join Date: Apr 2013
Location: SF Bay Area
Posts: 466
KCCO is on a distinguished road
My though is I'm going to hope the more experienced hop on and help us out. This is my first multi carb bike so this is new territory for me.
KCCO is offline  
Old 10-06-2013, 03:45 PM
  #5  
Moderator
MotoGP
 
E.Marquez's Avatar
 
Join Date: Apr 2006
Location: Kempner, TX
Posts: 4,255
E.Marquez is on a distinguished road
Originally Posted by Fistfullofthrotl718 View Post
So I made one of the manometers. Like found on here (Thanks). I am unsure as to (after a search) find the answer Im looking for. After syncing at a slightly elevated idle, then hold the throttle to about 4-5k rpm, its pretty far off balance. is this normal? and if not, how to correct? i cant get idle and elevated rpms to match well. thanks.
And you wont.

Sync them at idle.
E.Marquez is offline  
Old 10-06-2013, 03:56 PM
  #6  
Member
Squid
Thread Starter
 
Fistfullofthrotl718's Avatar
 
Join Date: Jul 2013
Location: Summerville, SC
Posts: 57
Fistfullofthrotl718 is on a distinguished road
Originally Posted by E.Marquez View Post
And you wont.

Sync them at idle.
Not trying to challenge you. Im just looking to get a better understanding of how this bike works. With that being said, why wouldn't getting more even pressure in the meat of the power be better for performance? Or is there any good documentation online that i can get a good insight on the hows and why's of these carbs? Thanks man. i appreciate it.
Fistfullofthrotl718 is offline  
Old 10-06-2013, 04:13 PM
  #7  
Moderator
MotoGP
 
E.Marquez's Avatar
 
Join Date: Apr 2006
Location: Kempner, TX
Posts: 4,255
E.Marquez is on a distinguished road
In a perfect world ...you would want air/atomized fuel flows matched in both carbs through the air cleaner, intake tract, carb, manifold, head and valves at all RPM and all vehicle air speeds.

Reality is ...it aint happening with any close to stock,, and likely not ever no matter how much R&D you put into it.

All that said........ My bike is pretty close on vac draw from 1800 where I set sycn to say a 3-4k steady RPM check
E.Marquez is offline  
Old 10-06-2013, 04:19 PM
  #8  
Senior Member
Superstock
 
KCCO's Avatar
 
Join Date: Apr 2013
Location: SF Bay Area
Posts: 466
KCCO is on a distinguished road
Follow up question, should I raise my idle to 1800 to set the sync then lower it back to 1200 after the sync? I have been trying to sync at 1200. I did put 50 pilot jets in the lines to calm down the movement of fluid a little.
KCCO is offline  
Old 10-06-2013, 04:39 PM
  #9  
Moderator
MotoGP
 
E.Marquez's Avatar
 
Join Date: Apr 2006
Location: Kempner, TX
Posts: 4,255
E.Marquez is on a distinguished road
Originally Posted by KCCO View Post
Follow up question, should I raise my idle to 1800 to set the sync then lower it back to 1200 after the sync? I have been trying to sync at 1200. I did put 50 pilot jets in the lines to calm down the movement of fluid a little.
1200 is on the low side of "standard" and I personally like mine at about 1400~1500
E.Marquez is offline  
Old 10-06-2013, 04:51 PM
  #10  
Senior Member
Superstock
 
KCCO's Avatar
 
Join Date: Apr 2013
Location: SF Bay Area
Posts: 466
KCCO is on a distinguished road
Thanks, I got them as close as they are going to get today. Within a cm or two of each other. Much better than what it was when I started.
KCCO is offline  
Old 10-06-2013, 05:23 PM
  #11  
Member
Squid
Thread Starter
 
Fistfullofthrotl718's Avatar
 
Join Date: Jul 2013
Location: Summerville, SC
Posts: 57
Fistfullofthrotl718 is on a distinguished road
Originally Posted by E.Marquez View Post
In a perfect world ...you would want air/atomized fuel flows matched in both carbs through the air cleaner, intake tract, carb, manifold, head and valves at all RPM and all vehicle air speeds.

Reality is ...it aint happening with any close to stock,, and likely not ever no matter how much R&D you put into it.

All that said........ My bike is pretty close on vac draw from 1800 where I set sycn to say a 3-4k steady RPM check
So is this the reason, or at least part of the reasoning for the different jetting per carb? To compensate for the pressure change after throttle is cracked?
Fistfullofthrotl718 is offline  
Old 10-06-2013, 07:56 PM
  #12  
Senior Member
MotoGP
 
7moore7's Avatar
 
Join Date: Jul 2010
Location: Phoenix, AZ
Posts: 3,867
7moore7 is on a distinguished road
I set my idle up higher for sync (1800-2000) then drop it to around 1300 for riding. This isn't based off of anything other than the manual saying to take measurements at idle and a higher rpm and sync them in the middle of that. Take that with a grain of salt.
7moore7 is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Dave Wicks
Technical Discussion
14
06-21-2008 06:56 AM
reaper
Technical Discussion
6
09-22-2007 10:15 AM
VTRFISH
Technical Discussion
0
08-16-2005 10:57 AM
mikecronis
Technical Discussion
9
05-26-2005 08:10 PM
cozart02
General Discussion
4
04-14-2005 06:31 PM


Thread Tools
Search this Thread
Quick Reply: carb sync


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.

All times are GMT -7. The time now is 09:22 PM.


© 2019 MH Sub I, LLC dba Internet Brands