Cold Start Problems

Thank you for telling your story, Bruce.  When you do pluck up the courage to go for a ride on your 1300, please let us know all about it.

I live in Bournemouth are you anywhere near?
Chrs
Bruce

Hi Bruce,
I'm in Christchurch so not too far

zed_thirteen wrote:

I live in Bournemouth are you anywhere near?
Chrs
Bruce

Hi Bruce,
I'm in Christchurch so not too far

Less than 10 kilometers from each other. You guys need to get out riding more often so you can spot each other. LOL. ( I should talk. There's probably a 1300 across the street from me. !#@!!@#!)

Hi Scotch,

Can you give me any tips on doing your pro mod? It looks to be straight forward, but I'm certainly not an expert at what's going on with the carbs. I've also purchased your cleaning tool a while back but haven't used it yet.

FYI, my 1979 Kz1300 has been very hard to start since I've owned it. Unfortunately I used to use starting fluid to get it going, which probably didn't help it any. I recently switched starters with another 1979 Kz1300 that I own. It seems to help a little turning it over, but it's still a real bear to start when cold and when it gets too hot.




Thanks,

George

I carried out Scotch's air jet mod a while ago and you can find a reasonably detailed description of the process here:
kz1300.com/index.php/carburators-fuel-in...ng-the-carbs?start=0
Hopefully, that link works OK.
I would add that whilst it really helped with cold starting, it made choke operation to maintain a stable and smooth running engine afterwards very diffiicult.  Like many others on this forum, I have found over 25 years of Z1300 A1 ownership that successful cold starts seems to require attention to detail in a number of areas - it rarely comes down to one specific issue.  I would support the requirement for a heavy duty, high quality battery, a well maintained starter motor without any shorts in the stator windings (an issue with mine at one point), spotlessly clean carbs, particularly the idle and choke circuits, good carb balance (using vaccum gauges) and dare I say it, ethanol free or at least less that 5% ethanol if you can't get it.
Even with all these areas in good working order, I have occasionally resorted to a 1 second blast of cold start fluid through the centre of the air cleaner for my first start after the winter layup.  The challenge seems to be getting fuel flow through the choke circuit after it has dried out.  Not sure why, but a lack of vacuum could be a culprit, exacerbated by slight stretch in the camchain delaying exhaust valve closure on the inlet stroke.  Difficult to prove without some complex experiments or a good engine simulation model with full wave effects. 
Hope this helps.

Cold start - hard starting:  First thing to check is the position of the Fast-Idle Cam roller. 
With FULL choke applied,  the roller must  ride-down the "steep-slope" all the way  allowing the throttle plates to fully close to the Idle gap. 
Applying Full choke does not close the throttle-plates totally !  The throttle-plates can only close to the gap set by your idle adjustment knob. 
Turn  IN the Fast-Idle cam screw until the roller is "just clearing" the cam with Full choke applied.  
If the roller is making contact with the cam in the Full choke position, the throttle plates will be open slightly more which reduces the already inherently low vacuum from efficiently/effectively drawing fuel into the choke system.   
This adjustment will now increase the Roller to Cam gap with the choke OFF, which is not necessarily a bad thing.  There must be a gap between the roller and cam with the choke OFF, to begin with. 

Installing a restrictor in the Choke-Air port significantly increases the vacuum in the choke system and choke-fuel draw is immediate but this is relative to the above so make the simple adjustment first and report back !