1980 KZ1300 - Hen's Teeth Do Exist

[Lucien Harpress]

Yup, you know it. Still futzing with stuff, whether or not it's for my own good.

So, replacing the plugs that capped off the emissions control system solved pretty much any problem related to deceleration and (possibly) low-throttle nastiness. But, knowing me, I can't leave well enough alone, and this also gave me the chance to focus on what's still acting up, namely:

- Popping out the left side exhaust while at idle, which changes to a consistent snapping at throttle.
- Runs nice and smooth while cold, vibrates like crazy when warm.

I can chock the second bit up to poor tuning (either float levels or mixture settings). Way I figure, I've got one cylinder set too rich, so she runs fine when cold, but when it heats up it starts to run ragged. Not enough to drop that cylinder entirely, but enough to make it run like garbage, and a 5-cylinder bike inevitably runs like crap. In fact, stock settings for the ilde mix are 1.5 turns out, but everyone who owns a 1300 runs them in the 3-3.5 range. I'm setting mine via colortune, so who knows. Guess I'll try to get mine to the leaner end of things, regardless.

The first is the biggest one- a miss or pop out the left side is something that has NEVER completely gone away. Best I got at this point is a vacuum leak- Thing is, these are THE stoutest intake boots I've ever seen- A metal plate mounts to the double intake on the engine block, and the whole thing is coated in rubber to make it seal, including the meaty oblong bit that clamps to the carburetors. Still, I pulled the center intake boot, and while the backside looked pretty good, it's also not perfect. I've got a set of replacements, so I'm hoping those work. If not- I'm out of ideas. Heck, I pulled the valve cover just to make sure the camshaft lobes weren't messed up (they weren't).

The only other big change is that I decided to put the original center carb back in- the replacement made no difference to the above problems, and it's in MUCH better shape than the one I temporarily replaced it with. Hopefully we'll get it all back together this weekend and get some results.

(Look, I'm not great at motorcycle repair. I'm blindly wandering my way through this the best I can, and learning more about engine maintenance than I knew before, which was "nothing". So I'm doing my best. )

...

Oh yeah, and I need a new front tire. Mine no longer holds air (and is probably overdue for a change).

[desertrefugee]

Keep the faith Lucien. That is a motorcycle worth the effort.

[Lucien Harpress]

Yeah, I'm getting there.

--Center carb body has been swapped back to the original. While I was at it I re-checked all three float levels, and evened them up. One was a bit off, but the service manual gives a range of fuel level settings (like 6.5mm to 8.5mm), so who knows if that will make a difference. If nothing else all three are identical now.

--Going back through some old photos, I discovered an oopsie on my part- namely painting the sealing surfaces on the intake boots. I'm curious if my left side popping is an intake vacuum leak, and while it's unlikely given how the intakes are set up (more on that in a second), I'm running out of other options. So I pulled the boots, and (sure enough) a decent bit of paint came with it.

Thankfully I have a spare set of intake boots, and while I did replace them, and fully admit I may have made a mistake for future Mike (me)- I ran some fuel-safe gasket maker on the engine-block side. You see, the carb side of the engine intake boots are extremely meaty- 1/2" rubber all around, clamped to the double throats of each carb. But on the engine side? A metal plate embedded in the rubber, with just a SUPER-thin layer of rubber between it and the head- which inevitably gets ruined the second the boots are removed. While sealer might fix this, there's the chance it gives me problems later on. I'm taking that risk.

--In less critical news, I've learned it's not cheap being dumb. I need a new front tire, as my current one no longer holds air. Stock size is a 110/90-18, which I ordered and received. AT which point I decided to actually look at the size of the current tire, which is an MR90-18. I always thought the front looked a bit chunky, which I love. Whelp, turns out an MR90-18 is equivalent to a 120/90-18, which it's that much difference, but is enough to get me to return the tire I have IN HAND so I can get the larger one. So while I technically have a tire, realistically I don't.

On the plus side, I've got a week of vacation in a couple weeks, and I'd like to make some major progress on at least a couple bikes during it, this one included. Let's hope.

[Lucien Harpress]

Got everything buttoned up and put about a tanks worth of gas through it, and at this point I'm considering any problems to be tuning issues. On the plus side, it's almost the best it's ever run. It can idle below 1000 rpm, the vibration at 3.5k is the best it's ever been, and accelerates and pulls wonderfully. A once-over after a long ride didn't show up any leaks, vacuum, header, or otherwise.

On the downside, I'm getting a lot of off-idle shenanigans. It's great when relatively cool (first starting out, running flat out with good airflow), but if it has a chance to heat up to the middle of the gauge or higher, it starts to get a nasty stumble right off-idle, worse if it's hotter or right after a hard decelleration. I'm still getting popping from the exhaust from both deceleration and crusing 25-35ish, with the throttle just barely cracked open. They feel related, but I'm no expert. If I power through the stumble though, it takes off again just fine.

When I set the mixtures this last time via colortune, I tried to get each toward the leaner end of things- screw setting on the 1300 is a whole thing (manual calls for 1.5 turns, most owners end up at 3-3.5 for... reasons?), and because I've had plugs load up if it idles long enough. But with 6 of them to set, I'm sure 1 or 2 are off. And hopefully that's my problem.

[Lucien Harpress]

I was a bit confused with my last ride- I seemed to be experiencing issues of both a lean condition (pops on deceleration) and a rich condition (lumpier running once it warmed up enough). Pulling the plugs after letting it idle for a while, I think the answer is.... both. Some plugs rich, some lean. I attempted to fix it, but... I think I went too far.





In all seriousness, the head bearings have always been a bit dodgy, and the last ride (combined with access to a garage with a larger working area) was what clinched it. The front end had a tendency to wander at speed, and it finally freaked me out enough to do something about it.

Since these photos have been taken, I HAVE installed a set of new All Balls head bearings, and have discovered replacing them is one of those jobs that's relatively easy to do but a right pain in the backside to actually GET to. It was relatively painless, and I'm 90% positive everything is in it's proper place. I haven't gotten the bike back on the road quite yet, but the difference between the new and old bearings is super noticeable.

I still have to re-connect all the electrical in the headlight bucket (brrrrr.....) but the worst of it is past. On the plus side, I have to do the same thing on my CB750, so know I know what I'm getting in to.

(And yes, before I got into changing bearings, I did fiddle with the mixture screws a bit. Hopefully that improves things. I'm eager to find out.)

[Lucien Harpress]

Yes, I realize that taking six years to "get" how good a bike is seems a bit excessive, but it is what it is. Thing is, eking towards getting the motor running correctly, combined with a couple quality of life improvements (brake rebuilds, steering head bearings) have really changed the riding experience for the better. Before, the vibration at 3.5k was annoying and the tracking was quite sloppy, to a worrying degree. Now? The bike feels a couple hundred pounds lighter through the corners- IF you're moving, of course. I'm still doing minor adjustments to the idle mix screws, but I'm both very close and heading in the right direction- any off-idle stumble is gone, and although a cylinder or two is still running a bit lean, it's nothing that affects down-the-road operation.

Long story short? For the first time in a long time I'm not worrying about running issues and enjoying the bike for what it IS. Which is a giant rocket of a bike that can still do moderate twisties if you're not dumb about it. Also, 60 to 80 comes SUPER-quick in top gear, and.... I need to keep an eye on that.

And so this isn't just me gushing about my bike... VANITY SHOTS!

[desertrefugee]

Great news Lucien! Now you need to put some miles on that thing before there's frost on the pumpkin. Enjoy it in it's native habitat. On the road! What you really need to do is pack it up and hit the highway for a few days. Nothing, and I mean nothing, accelerates the man/motorcycle bonding experience more than time on the road. That applies whether you run into issues or not!

Bike looks great! I need to finish up my Kawi 1300 once and for all. Been dancing around the maypole on that one. I am too easily distracted.

[Lucien Harpress]

I have been needing a vacation....

There'll be a bit of a longer test this weekend. The Gilmore Car Museum always has a classic motorcycle show, and while it's been pushed back and the swap meet cancelled, there's still going to be a get-together and show of sorts. Its about two hours each way from my place, which is a great benchmark for a long"er" trip.

[Jonesz]

I want one!! Nice looking machine Lucien

[Lucien Harpress]

Alright, forget what I said. Apparently, "One Good Day" is the exception. I'm attempting to set the idle mixtures via plug color, and... well, I genuinely have no idea what was going on a couple days ago when it ran well. The last two nights I've taken it out has featured a HORRENDOUS off-idle stumble, combined with what sounds like lean pops out the exhaust, even though I can start it without choke (which lends me toward thinking they are too rich). There's always a bit of a stumble (both sides this time, worse on the left) which seems like it goes away at about half throttle? But under that it's not great at all. If I hold the throttle steady it eventually lurches it's way out of it once the revs climb high enough, but it's very consistent.

I don't know. I'm going to start early and hit it hard on Saturday, rechecking the basics, I guess. Mixes, sync, that sort of thing. Cylinder 3 seems to run lean for some reason? I'm trying to remember if the compression on that one was slightly higher than the others, and if that means anything.

Regardless, I don't think Gilmore on Sunday is happening.

[CYBORG]

Alright, forget what I said. Apparently, "One Good Day" is the exception. I'm attempting to set the idle mixtures via plug color, and... well, I genuinely have no idea what was going on a couple days ago when it ran well. The last two nights I've taken it out has featured a HORRENDOUS off-idle stumble, combined with what sounds like lean pops out the exhaust, even though I can start it without choke (which lends me toward thinking they are too rich). There's always a bit of a stumble (both sides this time, worse on the left) which seems like it goes away at about half throttle? But under that it's not great at all. If I hold the throttle steady it eventually lurches it's way out of it once the revs climb high enough, but it's very consistent.

I don't know. I'm going to start early and hit it hard on Saturday, rechecking the basics, I guess. Mixes, sync, that sort of thing. Cylinder 3 seems to run lean for some reason? I'm trying to remember if the compression on that one was slightly higher than the others, and if that means anything.

Regardless, I don't think Gilmore on Sunday is happening.

Sorry about Gilmore.... but perhaps it's for the best. I thought about it for about a minute, but then thought abut the crowds etc. Could be the weather will have the final say anyway

[Lucien Harpress]

You know, I never even checked the weather. It's honestly been about 50/50 (rain or sun) every year I went, so getting rained out would be pretty on-brand.

[CYBORG]

You know, I never even checked the weather. It's honestly been about 50/50 (rain or sun) every year I went, so getting rained out would be pretty on-brand.

I hear you. Most years I have had the same feeling. And the weather here is often different then it is at Gilmore.

[Lucien Harpress]

I think I'm going to try for it. The weather's supposed to be nice, and I definitely need a reason to get out of the house. It's been..... a time.

To add to the list of "Things I Never Expected To Break (But Somehow Managed To Break Anyway)"-

1. Wires going into the fuel sender. (I'm getting real tired of prying open and re-using 40-year-old electrical connectors)
2. Fuel Filter. Like....how do you break a plastic fuel filter?

The second one is particularly annoying, because finding small-sized filters with 5/16" barbs is next to impossible, and the one I used is no longer manufactured.

On top of that I decided to re-check the sync to see if that would help my off-idle stumble and exhaust pops, and on the plus side, I was able to make it go mostly away at a couple points. Downside, now my sync is completely buggered up, I'm questioning the calibration of my gauges I spent several hours attempting to achieve, and I'm once again left wondering how I've managed to be SO bad at this.

[gltriker]

50 pages!