TOPIC:

Doing my best to get the ol' girl to 100%. I'm probably about 85% at the moment. She goes, stops, and turns real well, and I'm SUPER close on getting idle mixes set correctly, but off-idle response is still... well, garbage. And getting consistent nasty what-sounds-like lean pops out the left hand side, even though I've had mixture settings on all three cylinders on the left rich enough to foul plugs. But the off-idle is the most annoying. I'm hoping it's a slightly-off sync, but who knows.

On the plus side, I DID finally make a massive quality of life improvement in the ride quality a week or so ago. Pain in the butt to get to, but hey- head bearings are important, you know?

Lucien-Harpress wrote: Doing my best to get the ol' girl to 100%. I'm probably about 85% at the moment. She goes, stops, and turns real well, and I'm SUPER close on getting idle mixes set correctly, but off-idle response is still... well, garbage. And getting consistent nasty what-sounds-like lean pops out the left hand side, even though I've had mixture settings on all three cylinders on the left rich enough to foul plugs. But the off-idle is the most annoying. I'm hoping it's a slightly-off sync, but who knows.

On the plus side, I DID finally make a massive quality of life improvement in the ride quality a week or so ago. Pain in the butt to get to, but hey- head bearings are important, you know?

Now there's a job. Head bearings on a fully assembled bike. Hard to believe bearings that only turn 45 degrees can wear out. A job I prefer to do by "hanging the bike" rather than supporting on a pump cart, by Heh, you do what you have to. Kudos. Thanks for contributing.

It was my first time changing the head bearings. Good thing too, because I've got a CB750 that's going to be RIGHT behind it.

The lift I got relatively cheap from an auction when the local bike shot closed up. Between the lift stops and ratchet-strapping the bike down, it worked really well- I was able to whale on it enough to pop the races out, and it never moved. And the difference in handling is night and day. The guy I bought it from had the full Vetter tour package on it, so worn out head bearings weren't that much of a surprise. What WAS a surprise was how much a fresh set (from All Balls, would highly recommend) improved the ride. Before the bike had a bad tendency to track in big, slow arcs left and right that was really disconcerting, and just feel as super-heavy as it is. Now? Well.... I would never call a KZ1300 "nimble", but once at speed it feels as reasonable as a "normal" bike.

I'm really hoping I get the engine stuff figured out. I've got a taste of how good this bike CAN be, now it just needs to do it consistently.

Lucien-Harpress
That’s an interesting account of how replacement of your steering head beatings transformed the bike’s handling. It’s possible quite a few 1300 owners accept the steering / handling characteristics of these old bikes as “just the way the bike is” but could benefit in the same way you did.
Your bike looks good and largely original. Is it a very early serial number?

I'm sure you know this but I'll just go over it again since this type of issue keeps coming up again and again.
You're describing a typical low speed circuit blockage and the carbs on the KZ1300 seem to be really susceptible to this. I have a feeling that it has something to do with the low speed circuit (or idle circuit as most people refer to it as) passages and how fuel hangs up in them when the bike is shut down allowing fuel to evaporate and start leaving deposits behind until the deposits clog the passages.
If you look in the throttle throat at the butterfly plates, you'll see 3 tiny ports. 1 of those ports typically sits in front of the butterfly plate when the throttle is closed and it provides fuel at throttle stop idle. The other 2 ports at throttle plate idle are hopefully not in play until you start to open up the throttle and then they add fuel to the mix. What you're describing is a blockage in the second and third port causing a lean mixture at just off idle stop until the main circuit comes in to play. Also because these are CV carbs, the main circuit is somewhat delayed until the vacuum diaphragm starts lifting the throttle barrels. So, blockage in the low speed circuit is exacerbated even more so than a standard carb.
It's my belief that cleaning out this low speed circuit is problematic due to the nature of the passages and after rebuilding carbs for 40 odd years, I learned something from Scotch. In the past, I would dunk my carbs in carb cleaner for 1-1/2 hours then blow out all the passages with compressed air, wash in hot water and blow the passages again. 95% of the time, great job and the carbs were like new again. As for the 5%, it was always a low speed circuit (off idle blockage) that wouldn't clear and no matter what I did, I couldn't clear it so carb replacement was my resolve. Now I'm talking about 5% of 400-500 carbs since I was a tuneup mechanic at a Dodge Chrysler dealer.
What was I missing that I learned from Scotch 40 years after the fact? Scotch figured out that the tight spot in the carbs was at the transition ports in the throttle bore and the only way to clear the passage was by pushing the crap backwards to the flow of fuel in the passage i.e. force the crap back out the way it came in. To do this, you need to be able to direct compress air from the throttle bore side of the transition ports, through the ports and collect the crap back in the internals of the carb. That's not an easy task without special tooling and that's where Scotch's Cleaning tool comes in. It's a brilliant design, easy to use and allows the opportunity to add Lacquer Thinner through the tool to help dissolve the crap (usually a form of shellac, varnish) and clear the passage.

Bottom line- I was a skilled carb rebuilder and through this site learned an invaluable skill that I will be forever grateful for. I too now have a "Scotch's Cleaning Tool" and plan on building a nice display rack for it and displaying in my shop front and center. For me, the Tool is a subtle reminder that you can always learn something from others and no matter how good you think you are, you can always improve so take all learning opportunities that come your way. Also when I need the tool, I know exactly where I stored it for future use

Wife has had me doing a lot of DIY since march, en-suite, new shed build from scratch, hot tub - but I did get some time to work on a rolling stand for my spare engine in the hopes of getting it running . Also cut a couple of gaskets on laser cutter - so far transmission cover and top hose housing