Aftermarket upgrades that are actual upgrades.

You didn't mention budget, so we'll go with bang-for-the-buck:

Older bikes were built to a price point, and this is often evident in the electrical system.

Installing modern blade fuse holders in place of the tube fuses is worthwhile in some cases, especially on heavily loaded circuits.  The single-fuse-for-the-whole-bike situation on Z1's comes to mind.

Not really a 'part', but No-Ox-Id A electrical contact grease applied to old harness pin connectors will keep oxidation at bay and improve conductivity practically indefinitely.  Clean the pins first, making  sure the female pins grasp the male pins securely.  Clean all motor and chassis grounds and install star washers for bite.

On many bikes, 12V(+) coil power is routed through myriad connectors and often at least two switches, all of which can degrade over time.  Rotary ignition switches are a common culprit.  The resulting voltage drop at the coil primary winding(s) results in reduced secondary winding output, which causes weak spark at the plug gap(s).  Unexplained plug fouling, mysterious performance problems and hard cold starts mostly cover the possible symptoms.  The modification often referred to as the 'WiredGeorge coil mod' is a simple relay addition that safely bypasses the problematic switches and connectors in the serpentine OEM circuit, wherein the relay is used to apply switched, full battery power directly to the coil primaries.  A fat, hot spark even when cold cranking is the benefit.

The relay is a very common automotive relay that can be found at auto parts stores, Amazon, FleaBay etc. for less than $10.00.  A simple relay wiring harness can be created using OEM style connectors, a crimp tool and a few feet of 16 ga. or 18 ga. primary wire that will make the mod plug & play, so the OEM harness doesn't have to be cut or modified in any way.

Circuit diagram here:
www.wgcarbs.com/index.php/using-joomla/e...-categories/89-coils

Good Ridin'
slmjim & Z1BEBE

 

wrote:

You didn't mention budget, so we'll go with bang-for-the-buck:

Older bikes were built to a price point, and this is often evident in the electrical system.

Installing modern blade fuse holders in place of the tube fuses is worthwhile in some cases, especially on heavily loaded circuits.  The single-fuse-for-the-whole-bike situation on Z1's comes to mind.

 

Also this. Can't believe I forgot about it.

Here is the one I installed on the KZ440B project bike. It didn't suffer from the single-fuse issue you mentioned but it's still nice to get rid of the Buss fuses. The box itself is very simple and was about $7 on Amazon.

 

Threadsurrection! 

So just to kind of follow up and expand this thread a little, one thing that got me thinking is aftermarket brands that can be trusted. Again, where OEM might largely be considered best, there are some companies that are providing parts that are as good or better right? I’m curious about those. 

Emgo - One brand name I see a lot is Emgo. They make brake pads and rotors, but are they any good?

EBC - Same question! Can we trust EBC-made components? They make brake pads, rotors, and clutch kits. 

HiFloFiltro - Easy one to find on EBay, but again, good product? Or not so much? 

Caltric - I don’t even know if they make anything relevant to any KZ engine, but their prices are very low. Too good to be true, or the best deal around? 

BikeMaster - Same question as all above, any good? Or one to avoid? 

Supersprox - So many aftermarket gears and chains, but are they worth the money? 

Sunstar - More aftermarket gears. But again, any good?  

Inquiring minds would like to know. 

Personally I have used  Emgo, EBC, and Sunstar with positive results.
Others with positive experiences 
D.I.D   chain
Manley and Kibblewhite       valves
APE     performance parts
Dyna     Ignitions 
Liska   cam  driveline  gears
MTC , Wiseco  pistons
Cometic    gaskets
Viton   valve seals
Ikon  , Olin    rear shocks
Not knocking OEM / stock  , but there  are other options
There are more quality vendors out there , Just  these for now
Dave

EMGO:
   OEM Z1 cartridge filters have a very large number of holes in the inner tube and outer sleeve to allow the high volume of  low-pressure flow that Mama Kaw's roller crank motors depend on.  The 20 or so EMGO Z1 cartridge filters we have on the shelf show somewhat fewer but noticeably much larger holes resulting in what our calibrated eyeballs suggest is at least an equal area open to flow.  We use EMGO filters in our Z1's without hesitation.  Many aftermarket Z1 filters have noticeably fewer holes in the inner tube and outer sleeve, limiting flow area, that we believe would limit flow volume and create excessive pressure drop across the filter.  We will not use filters made like that. We've also used a few EMGO spin-on filters on our pair of '93 CB750 Nigthawks with no problems.  Inner tube perforations appear to be equivalent in open area to OEM Honda filters.
   We've used EMGO Z1 replacement ignition coils a few times.  They fit perfectly & appear to perform the same as OEM coils on stock motors in our experience.
   We've used EMGO rear brake shoes on two Z1's without problems.
   We've used EMGO replacement ignition switches on Z1's that work fine.  Longevity is unknown.

HiFloFiltro:
   We've used a half dozen of their OEM-equivalent, spin-on filters we got for a song in a parts lot on our Nighthawks and ST1300 with no problems.  CalSci did an oil filter study (now somewhat dated) that deemed HiFloFiltro filters to be average filters at a good price.  CalSci also noted ancedotal evidence of  an event on a Hyabusa, wherein “an aged anti-drainback valve on a Hi-Flo [sic] filter that would not open, thus cutting off all oil pressure to the entire engine.”

motorcycleinfo.calsci.com/FilterStudy.html

   At any rate, we prefer the very common & slightly longer 7317-style spin-on filters for our '93 Nighthawks and ST1300 due to the additional filter media that the additional length allows.

BikeMaster:
   The original Yuasa AGM battery in our 2009 ST1300 lasted 6 yrs.  The BikeMaster AGM battery that we used as a replacement lasted 5 yrs. & cost about 2/3rds. that of a new Yuasa battery.  We'll call it a wash.
   When we needed to replace the aging & cracked rubber rubber turn signal assemblies on our pair of '93 Nighthawks, we tried BikeMaster items first due to the cost of OEM units.  The front running lights of the BkeMaster units weren't wired correctly & interfered with operation of the turn signals.  We exchanged them for two more sets of BikeMaster units that misbehaved the same way on both bikes. They were also clearly poorer quality of internal build compared to OEM.  We returned the second set & installed new OEM units on both bikes that work perfectly.  YMMV on other electrical parts.

SunStar:
Three sets each (and counting, on the 4th. set, each) on our pair of '93 Nighthawks since we replaced the OEM chain & sprockets at around 18K miles. Both bikes now have ~70,000 miles on them.  Chains have worn out before the SunStar sprockets.  Performance & fit of the SunStar sprockets have been exemplary.  We've also used a few on Z1's with good results.

Good Ridin'
slmjim & Z1BEBE

EBC - yes
Supersprox - yes
Interstate AGM batteries - yes
D.I.D. and EK chains - yes
A.P.E. - yes

CALTRIC NO

Motobatt batteries. Mine is going on 8 years. 

Excellent thread, thanks to all those who contributed so far.

On the "All Balls" head bearings; I would be surprised if they actually manufacture tapered roller bearings themselves. Aren't there stock industrial bearings that will fit? A bike's headstock is not under a great deal of load, so pretty much any good quality pair of industrial tapered roller bearings that fit should do the job - or am I missing something here? Have Kawasaki sized things such that the bearing needed is a bastard size? I once had this with a jetski starter motor.

On the Aprilia using balls, don't forget that the highest precision machine tool spindles use "ball bearings" in preference to tapered rollers - actually angular contact bearings, which may well be what the Aprilia uses. Perfectly acceptable in this application.

Otherwise, great advice. I hadn't thought about the wiring harness, fabbing one from scratch and using better connectors sounds like a really useful upgrade.

Some of this should be transferred to the FAQ start up section 

Dragging this dusty thread off the shelf to ask a question. Do off-the-shelf spray cans of brake cleaner work? Are they safe to use anytime without worrying about long-term degradation? I’ve seen multiple brands such as:

CRC Brākleen
3M Brake Cleaner
PB Blaster Brake Cleaner
+more

So do they work? What about chlorinated versus non-chlorinated? That seems to be a thing. 

And if these aerosol cleaners are a bad product, what do you recommend for cleaning brakes? 

yes they work. the chlorinated v non-chlorinated is mostly a clean air thing. Turns out chlorine is pretty bad to release into the air, who'da thunk? Also if you are going to clean parts to weld, you definitely want a chlorine free brake cleaner because super heating solvents with chlorine will make a toxic gas that will kill you - think WW1. I use the cans for some stuff because they are easy to use and the pressure i great for blasting things out, but they are not 100% residue free, which is why Vintage Brake recommends using pure acetone for cleaning brake rotors.