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jamo
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Machine faltering carbs?
09/28/18 at 05:52:50
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Hi All
I am at my wits end. My 1983 R65LS. Was running rough like running to higher gear at to lower speed no matter what gear it was in.
I had all the parts to overhaul the carbs. So set about the work. I had the carbs balanced and timing set by a professional he also fitted new pushed tubes and rubbers at the same time.  Twistgrip and all cables have been changed.
The machine runs lovely at tickover and at full throttle. But at a constant speed at 30/40 mph,the thing if faltering  it make riding in traffic and bends a little interesting. Without pulling carbs to pieces again any ideas where I go next?
  
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Barry
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Re: Machine faltering carbs?
Reply #1 - 09/28/18 at 06:49:24
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At a steady 30/40 mph the carbs are still running substantially on the idle circuit so although you don't want to get into them again the idle passages and jets are where I'd look assuming valve clearances and plugs/ignition timing have been checked.

Depends who it was of course but having the carbs balanced by a professional is not an absolute guarantee of it been done correctly.
  

Barry Cheshire, England 79 R45
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Bob_Roller
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Re: Machine faltering carbs?
Reply #2 - 09/28/18 at 13:55:50
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Are there rubber caps or some other means of closing off the ports on the carbs where the manometer, gauge hoses connect ??
  

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Mrclubike
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Re: Machine faltering carbs?
Reply #3 - 09/28/18 at 21:10:37
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Yes they are threaded so you can run a screw into them
  

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Barry
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Re: Machine faltering carbs?
Reply #4 - 09/29/18 at 14:41:51
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I once left those screws out after balancing.

It didn't run too badly but I could tell something was not quite right at low speeds.  If the the screws are missing they are:

M3.5 x 0.6  part number 13 11 1 259 869.
Washers are 13 11 1 259 870.
  

Barry Cheshire, England 79 R45
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tunnelrider
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Re: Machine faltering carbs?
Reply #5 - 09/29/18 at 15:13:15
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Barry wrote on 09/28/18 at 06:49:24:
assuming valve clearances and plugs/ignition timing have been checked.


2nd that - I had an annoying stumbling around those speeds before, bought a timing light to check and turned out the timing was out.
  

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jamo
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Re: Machine faltering carbs?
Reply #6 - 10/01/18 at 03:02:01
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I am now buying a timing light and vacuum gauges.
Also an over site on my part did not check the jets supplied to me were the same as I removed. So it is off with the carbs again.
  
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Barry
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Re: Machine faltering carbs?
Reply #7 - 10/01/18 at 06:35:44
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Have you considered making a vacuum balancer. Just a length of plastic tube, some ATF or other thin liquid and a means of mounting it.





  

Barry Cheshire, England 79 R45
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jamo
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Machine faltering carbs?
Reply #8 - 09/28/18 at 05:51:22
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Hi All
I am at my wits end. My 983 R65LS. Was running rough like running to higher gear at to lower speed no matter what gear it was in.
I had all the parts to overhaul the carbs. So set about the work. I had the carbs balanced and timing set by a professional he also fitted new pushed tubes and rubbers at the same time.  Twistgrip and all cables have been changed.
The machine runs lovely at tickover and at full throttle. But at a constant speed at 30/40 mph,the thing if faltering  it make riding in traffic and bends a little interesting. Without pulling carbs to pieces again any ideas where I go next?
  
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Matt Chapter
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Re: Machine faltering carbs?
Reply #9 - 10/02/18 at 09:41:56
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Sounds like carbs, so it's probably electrical.  Grin

Honestly I would go for a full tune up if you haven't already.  Perhaps there's a sticking choke mechanism, or there's a tear in the carb diaphragms?
  

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jamo
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Re: Machine faltering carbs?
Reply #10 - 10/02/18 at 10:18:57
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All new jets and diaphs in the carbs. Only thing done to carb bodies was an ultrasonic clean. I do not know about the drillings
  
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