Author Topic: Need help bench syncing  (Read 1195 times)

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Offline BlindJoe

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Need help bench syncing
« on: March 16, 2008, 04:41:27 pm »
        Here is a pic of my pd46 carbs ('77 550k); the throttle is fully closed, slide #1 is adjusted to be closed all the way, and #2 is shown at the default, unchangeable position. I was under the impression that all the slides should have about an 1/8 th in. gap on the intake side with the throttle fully closed, but as you can see #2 is a lot higher than 1/8 th in. Could somebody please clarify all of this for me? I've been having high idle issues and I'm trying to pinpoint the issue.

Thanks!

« Last Edit: March 16, 2008, 04:43:24 pm by KottkeHead »

upperlake04

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Re: Need help bench syncing
« Reply #1 on: March 16, 2008, 04:59:43 pm »
 If your slides are in those positions with the throttle closed, its a good bet your  high idle reason is there.
  I'm not familiar with your  particular carbs adjustments but conceptually,  adjust your throttle cable or main idle thumbscrew so that #2 has the 1/8" gap, then adjust 1-3-4 individually to match #2. That should get you in the ballpark.
« Last Edit: March 16, 2008, 05:01:14 pm by upperlake04 »

Offline paulages

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Re: Need help bench syncing
« Reply #2 on: March 16, 2008, 05:06:30 pm »
1/8" is just a reference point. the actual height will be determined when properly syncing and is based on vacuum, not a height measurement. to get them in the ballpark, take anything 1/16"-1/8" or so the back end of a drill bit works well), and adjust each slide separately until they are all at this point. this will get them close enough to run, but will still need a proper syncing.
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Offline BlindJoe

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Re: Need help bench syncing
« Reply #3 on: March 16, 2008, 05:12:15 pm »
1/8" is just a reference point. the actual height will be determined when properly syncing and is based on vacuum, not a height measurement. to get them in the ballpark, take anything 1/16"-1/8" or so the back end of a drill bit works well), and adjust each slide separately until they are all at this point. this will get them close enough to run, but will still need a proper syncing.

I'm aware of this, but my problem lies in not being able to adjust the #2 slide at all in order to lower it, the position it is at in the picture is as low as it will go.


Offline Cvillechopper

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Re: Need help bench syncing
« Reply #4 on: March 16, 2008, 05:25:09 pm »
Lift the other 3 to match.   ;D

Seriously.  That is WAY off and that will absolutely give you idle issues.  When you say that 2 is as low as it will go, do you mean that the adjustment nut has no more room to move or that the slide will not go any further even with the adjustment nut off?
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Offline scondon

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Re: Need help bench syncing
« Reply #5 on: March 16, 2008, 05:28:14 pm »
 The slides will close only as far as your lowest one. You may have to raise 1,3, and/or 4 in order to get #2 to drop.  Something is definitely amiss and I'm surprised the bike started at all with that much difference in slide height.

   Yeah, what 'chopper said(I type slow) :)

   #2 has no adjustment nut at all on the later carbs, 'chopper. It's fixed.
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Offline pampadori

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Re: Need help bench syncing
« Reply #6 on: March 16, 2008, 05:31:47 pm »
when you adjust the other 3 cyl higher, that inturn will lower this cyl.  when you adjust one, the others move too.
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Offline BlindJoe

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Re: Need help bench syncing
« Reply #7 on: March 16, 2008, 05:46:05 pm »
Ok, I'll give it a try, thanks for your help guys!

Offline Cvillechopper

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Re: Need help bench syncing
« Reply #8 on: March 16, 2008, 06:01:45 pm »
The slides will close only as far as your lowest one. You may have to raise 1,3, and/or 4 in order to get #2 to drop.  Something is definitely amiss and I'm surprised the bike started at all with that much difference in slide height.

   Yeah, what 'chopper said(I type slow) :)

   #2 has no adjustment nut at all on the later carbs, 'chopper. It's fixed.

My bad.  I missed that.
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Offline TwoTired

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Re: Need help bench syncing
« Reply #9 on: March 16, 2008, 06:50:01 pm »
Maybe too late to help, but...

Back off the big idle knob adjustment so the slides bottom out,  Make sure the fast idle cam on the choke mechanism is also NOT blocking full slide closure.

Since # 2 is non-adjustable, back off the individual slide adjustments on the others until # 2 is fully floored in the carb bowl.  During this, make sure the big idle knob and the choke cam are not giving interference.

Now adjust #1, 3, 4 in turn so that they, too, just rest on the carb throat floor.

Now turn the big idle knob until the slides are about 1/16 open on the engine cylinder side.

Reinstall the carbs and run the engine.  Adjust idle knob when warmed up and choke no longer needed.

Vacuum synch the 1,3,4 carb to match # 2.    Do this after you have completed all the other standard tune up items.  Tappets, cam chain, points/ timing.  Plug gap/cleaning,  air filter, etc.

Then do the Idle mixture screws for max RPM, while resetting the idle knob for correct idle speed.

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Lloyd... (SOHC4 #11 Original Mail List)
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Offline BlindJoe

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Re: Need help bench syncing
« Reply #10 on: March 16, 2008, 10:13:36 pm »
So I think I finally got it figured out, it just took a little time fiddling with the adjuster screws to figure out how to lower #2. Now I just got to get it dialed in. Wish I would have done it right the first time, could have saved my self a lot of time and frustration.
 
Thanks for your help everyone.