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Very Hot Topic (More than 25 Replies) Main jets? (Read 1139 times)
Justin B.
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Re: Main jets?
Reply #30 - 05/13/18 at 20:30:14
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Fantastic!
  

Justin B.

2004 BMW R1150RT
1981 R100RT - Summer bike, NEKKID!!!
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Tony Smith
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Re: Main jets?
Reply #31 - 05/13/18 at 21:32:28
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DadsR65 wrote on 05/13/18 at 19:26:08:
Update:  seems that points gap was too tight.  I corrected it and re-timed and bike pulls like a champ now!


I am VERY glad that you have fixed the problem.

You are also now entitled to be a card carrying member of the "When you think it is carbs, it will be Ignition and when you think it is ignition it will be carbs" society.

Oh....And it was nothing to do with those "evil" non-OEM diaphragms!
  

1978 R100RS| 1984 R65 | 1984 XT350 | 1992 KLE500 | 2002 R1150GSA
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wilcom
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Re: Main jets?
Reply #32 - 05/13/18 at 23:09:12
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"Once you are absolutely sure that your carbs are OK, start checking ignition components - on the well established principle that if you *think* it is fuel it will be electrical - and vice versa"

........as Tony Smith said!
  

Joe Wilkerson
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DadsR65
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Re: Main jets?
Reply #33 - 05/14/18 at 05:57:10
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Thanks to all for the help!

Next issues are bouncy speedo and inability to get idle low enough.

On the idle, I can get it down to ~1200rpm and balanced, but no lower.  If I continue to back out the left side idle speed screw, it no longer touches the throttle lever.  I can push on the throttle lever with a long screwdriver and idle will drop.  This tells me it's a mechanical issue.  I ordered new throttle return springs as step 1.  If that doesn't work, then new throttle cables.
  
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Barry
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Re: Main jets?
Reply #34 - 05/14/18 at 06:52:13
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DadsR65 wrote on 05/14/18 at 05:57:10:
Next issues are bouncy speedo and inability to get idle low enough.


Bouncy speedo could be the cable.  You could try driving the speedo using something like an electrical screw driver or variable speed drill to see if the speedo unit itself is OK.  If not OK then generally a faulty speedo is best repaired sooner rather than later before more expensive internal damage is done.


DadsR65 wrote on 05/14/18 at 05:57:10:
On the idle, I can get it down to ~1200rpm and balanced, but no lower.  If I continue to back out the left side idle speed screw, it no longer touches the throttle lever.  I can push on the throttle lever with a long screwdriver and idle will drop.  This tells me it's a mechanical issue.  I ordered new throttle return springs as step 1.  If that doesn't work, then new throttle cables.


It could be cables but it would be unusual if stock return springs were at fault as they are actually a fair bit stronger than they need to be. It's more likely an issue with the butterfly spindle or alignment. Has the butterfly been detached from the spindle and if so did it go back the right way up. Was it correctly centred in the venturi before tightening the screws.
  

Barry Cheshire, England 79 R45
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DadsR65
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Re: Main jets?
Reply #35 - 05/15/18 at 03:49:29
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Barry wrote on 05/14/18 at 06:52:13:
DadsR65 wrote on 05/14/18 at 05:57:10:
Next issues are bouncy speedo and inability to get idle low enough.


Bouncy speedo could be the cable.  You could try driving the speedo using something like an electrical screw driver or variable speed drill to see if the speedo unit itself is OK.  If not OK then generally a faulty speedo is best repaired sooner rather than later before more expensive internal damage is done.


DadsR65 wrote on 05/14/18 at 05:57:10:
On the idle, I can get it down to ~1200rpm and balanced, but no lower.  If I continue to back out the left side idle speed screw, it no longer touches the throttle lever.  I can push on the throttle lever with a long screwdriver and idle will drop.  This tells me it's a mechanical issue.  I ordered new throttle return springs as step 1.  If that doesn't work, then new throttle cables.


It could be cables but it would be unusual if stock return springs were at fault as they are actually a fair bit stronger than they need to be. It's more likely an issue with the butterfly spindle or alignment. Has the butterfly been detached from the spindle and if so did it go back the right way up. Was it correctly centred in the venturi before tightening the screws.


The butterfly on both carbs did come out during rebuild.  Shafts, o-rings, and tiny screws are new.  I've double checked them and they appear to be correctly installed.  Also no light coming through any gaps.  The fact that I can push on the throttle lever at the carb and get the revs to drop still makes me think cable and/or spring.
  
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