Riders Of Vision

General => TechTalk => Carburetors => Topic started by: Lead_Deficiency on September 01, 2005, 06:03:50 PM

Title: Idle carb sync
Post by: Lead_Deficiency on September 01, 2005, 06:03:50 PM
I was checking the sync today and found that @ revs the sync is dead on, but at idle the front cylinder pulls more than the rear.

Should I be concerned about this or is there a suggested fix.

I've never been impressed with the way the bike starts once it is warm, but starts great when cold. I often find myself adjustiing the idle speed screw, but I think the spring is just soft.

Title: Re: Idle carb sync
Post by: Lucky on September 02, 2005, 07:03:58 AM
I have heard of people adjusting the synq while holding the carbs at a higher RPM, but i've never seen or heard of any manual or dealer advising to do it at anything other than idle. it's how i do it & the bike runs great...
Title: Re: Idle carb sync
Post by: Walt_M. on September 02, 2005, 11:01:13 AM
Carb synch is done at idle, 1300RPM on the Vision. If you can't get the synch correct, there may be something else wrong. Valve adjustment?
Title: Re: Idle carb sync
Post by: Lead_Deficiency on September 04, 2005, 12:56:56 PM
 I set the sync @idle, the rod adjustment was so close it was almost not worth tryiing to adjust it.

The valve clearances was a good sugestion, I can't hear any ticking but maybe they should still be checked (16,000 miles on bike0, I don't know when it was done by the previous owner - sounds like a winter project.
Title: Re: Idle carb sync
Post by: Rick G on September 15, 2005, 02:30:40 AM
It depends on which  scool you come from  I've always syncd  at 2500 rpm ,  on any bike . You don't spend much time at idle  !
Title: Re: Idle carb sync
Post by: Lead_Deficiency on September 15, 2005, 09:52:38 PM
Yes, thats was what I was thinking to. I was going to take another shot at it.  - you've been awol for a while rick.
Title: Re: Idle carb sync
Post by: Coil Coyle on September 16, 2005, 04:31:27 AM
Rick,
You don't start the engine at 2500 RPM either.

I agree with Walt, synch at idle and adjust the valves.

$00.02

coil
Title: Re: Idle carb sync
Post by: silicon_toad2000 on September 16, 2005, 08:59:19 PM
Lead, whichever way you decide to go, at idle or at revs, when you change the revs the synch will change, the cylinders don't have the same efficiency as they have different exhausts, and have different intake timing while sharing the same airbox.
Personally I think do the synch at idle, generally your idle mixtures are set the same (so many turns out) so both carbs need the same amount of vacuum to suck the same amount of fuel. At speed the kind people at yamaha have allready allowed for the difference in vaccuum with the different jet sizes in the front and rear carbs.
Title: Re: Idle carb sync
Post by: Lead_Deficiency on September 16, 2005, 11:48:33 PM
Well lots of opinions, seems they all make sense.  ??? That larger rear jet has to be there for a reason.

Who was it that used an exhaust gas analyser to check their bike? wonder what their set up is like.

I could almost smell another poll
Title: Re: Idle carb sync
Post by: Rick G on September 18, 2005, 02:50:39 AM
I didn't "invent " syncing at 2500 . It was revealed  to me by a tech at YIC.  I've talked to several  "senior" wrenchs about it and the concesis is to sync at 2500, or there abouts.
Title: Re: Idle carb sync
Post by: Rick G on September 18, 2005, 02:54:33 AM
Hi lead , yes i have been absent . we moved oul moble home to  a lot , as opposed to  a moble home park. and had no utilities for a while , still don't have gas yet. Also my wife has been very ill  and in the hospital  , so I have been pretty bus, thanks  for thinking of me. .