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Choke air mod - splitting the carbs 1 month 6 days ago #30229

  • Neville
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Although my 79 Z1300 starts well from cold or warm if I use it fairly regularly, it seems to take a good deal of cranking to get it started after a winter lay up (and yes, I have removed the fuel solenoid and have a Pingle fuel  tap).  So, I decided to have a go at fitting Scotch’s choke air mod.  First step is to remove the carbs and separate them.  The M6 screws holding the carbs to the bottom bracket were not going to shift using a conventional approach so I used a clamp arrangement holding my JIS screwdriver and a spanner fitted to the hex shaft to get some turning leverage.  I've used this approach in the past with some success.



3 screws came out OK but the fourth just sheared after about one turn.  **gger.  At this point I decided to leave the screws in place holding the bracket to the centre carb as it’s not necessary to remove them to fit the new choke air jets.



Drilling out steel screws in aluminium castings is always a worry as the aluminium is so much softer and if you don’t drill in the centre of the screw, it rapidly drifts off to one side when you break through the side of the steel screw.  I used a bench drill to try and keep it straight and also centre punched the bolt in as close to the centre as possible.



I’ve found it best to drill out in stages, so for this M6 screw,I started with 2.5mm and then increased in three stages to 5mm, the tapping drill size.



Although the drill was slightly off centre, I was lucky and a couple of turns with an M6 tap released the remains of the screw left in one side of the threads.  A run down to the bottom of the hole with a plug tap cleaned up the thread.Maybe now I can get on with the choke air mod... 

 
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Choke air mod - splitting the carbs 1 month 6 days ago #30230

  • biltonjim
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Well done getting the broken screw out! It is a big advantage to have a bench / pillar drill / drill press for such jobs.  I recall Scotch using his to hold a screwdriver bit for removing troublesome screws - similar in principle to your use of screwdriver and clamp.
Keep us informed on your progress and outcome.
 
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Choke air mod - splitting the carbs 1 month 5 days ago #30231

  • dcarver220b
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Well done! Now off the mod!

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Choke air mod - splitting the carbs 1 month 4 days ago #30236

  • scotch
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Yes:  Good job on that broken bolt.  Creative with the clamp but wonder why you didn't use the drill-press? 
In my post " '79 carb rebuild"  I showed my carbs in a heating box.  Pre-soaking the fasteners overnight with some penetrating oil and then heating and cooling the carbs (expansion/contraction?) - all the fasteners came out.  To what degree (no pun intended) this procedure helped is difficult to say.  Nothing broke, so......  
 
1980 KZ 1300 sr# KZT30A-009997
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