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'91 - '03 750 Nighthawk longevity & high mortality parts? Other thoughts. Long post.

slmjim n Z1BEBE

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Long post to follow. Thinking cap suggested.

We're on multiple fences re: keeping our His n Her pair of '93 Nighthawks we bought new. Both have 70,000+ relatively trouble free, adult touring miles on them. We never wailed on them & they're always garaged. Very well maintained by us. We're Kawasaki Z1 collectors & restoration hobbyists with 40-+ yrs. experience.

We're both over 70. The Lovely Z1BEBE decided to hang up her keys last year, so I pickled her red '93 Nighthawk for long-term storage. My blue '93 Nighthawk needed the carb diaphragms replaced this year, as one was holed. A cheap rack of very-low-mile 750 Nighthawk carbs from fleabay solved that.

I'll continue Ridin'; Joyrides solo on my 750 when the spirit moves me, and Z1BEBE is happy doing the passenger thing on our ST1300A, with a rarel two-up on my Nighthawk, although we'd both like a top box w/ backrest for her.

So, we have two '93 'Hawks, I'm in the autumn of my Ridin' career, and I don't know how many more years I'll be Ridin'. My Ridin' will be split between my Nighthawk, the ST1300A, and whichever of our Kawasaki Z1's we prep for a given season.

Caveat - we're out of room. Garage is full with two vehicles and three bikes, lawn care equipment, and a Honda Hobbit PA50-II moped. The basement shop has six bikes in it. Another one cannot be squeezed into the shop without completely blocking the bike service area. One more bike isn't gonna happen anywhere here at home.

In all cases mentioned below, we keep our collection of Kawasaki Z1's.

Fence 1 - Keep both Nighthawks & prep one alternately each year for maybe, maybe, 2,500 mi. per season. Likely less. This bring up the question of longevity. The CB750 motor is one of the most robust ever manufactured. But, like any machine, there are certain 'high mortality' parts within. "High mortality' is not to be confused with consumable hardware such as spark plugs, chains/sprockets, wheel bearings, brake pads, cables & such.
Upside - We know the model well, know the exact 70,000+ mi. history of our bikes, and have all the docs & most spares we're likely to need.
We have irrational sentimental attachment for our Nighthawks. We've spent 30 yrs. of our 34 years marriage & 70,000 mi. all over two-lane America on them. They mean something to us.
Cost - essentially nil.
Cheap to insure.
Reasonably deep interwebs knowledge base.
Downside - 70,000+ mi. Brings up the longevity Q1 & Q2 questions below.
Not easy to set up for comfy passenger two-up Ridin' + storage due to most accessories NLA.

Q1) We see anecdotal evidence the CB750 Nighthawk motor typically runs trouble-free for 100,000 mi. with good care & maintenance. What sat ye about longevity? Is 100,000 mi. a reasonable estimate based on history of this motor's design?

Q2) What are the (relatively) high-mortality parts in the '91 - '03 750 motor, or the bike in general? Our list so far is:
Turn signals (stalks breaking).
Switchgear, particularly the start switch itself becoming intermittent in the 'RUN' position re: the headlight not always coming on after the motor starts. May be NLA.
Tach. Won't break the bike, but aggravating. Later tachs seem to have solved the problem. We have a late NOS tach on the shelf just in case.
Valve cover gaskets. We replaced both @ ~50,000 mi. or so due to slow weeping developing. Easy.
O-rings at the fuel 'T' & junction pipes. Easy.
Petcock - one failed years ago. Leaked in the 'OFF' position & motor went into hydraulic lock. Rebuild kit failed. Replaced with new OEM. Not exactly high-mortality, but still...

That's about it for our high-mortality list. Any suggestions, parts we've missed?

From here down we're mostly talking to ourselves. It just helps to see things in print sometimes for thoughts to jell. We're most interested in the above. Feel free though, to chime in on how you've managed similar considerations.

Fence 2) Sell both our 750's & replace with one, nice, much-lower-mileage '91 - '03 Nighthawk. They're out there.
Upside - much newer bike we're very familiar with, & have the service manuals & some spares on the shelf.
Still cheap to insure.
Downside - We have irrational sentimental attachment for our Nighthawks. We've spent 30 yrs. of our 34 years marriage & 70,000 mi. all over two-lane America on them.
Unknown history.
Not easy to set up for comfy passenger two-up Ridin' + storage due to most accessories NLA.
Cost.

Fence 3) An friend & fellow vintage bike resto hobbyist has a one-owner, low-mile (800 mi. !) 2017 CB1100EX for sale. We sell both 'Hawks, replace them w/ the CB1100 set up w/ top box/backrest.
Upside - Much newer bike. Current OEM parts support. More power than any 750.
Can easily be set up with a top box using currently-available rack & box for backrest & storage for short two-up day / weekend Ridin'.
Known history of this CB1100.
Reasonably deep interwebs knowledge base.
Downside - We start from scratch on parts stock, documentation and a learning curve of a different, much more complex (ABS, fuel injected) bike.
Spoke wheels (tubes) & uncommon tire sizes.
Also, irrational 'Hawk attachment & etc.
More expensive to insure.
Cost++

Fence 4) Realistically, how many more 3+ week, 2,000+ mi. tours are we likely to do on the ST1300A? The older I get, the taller & heavier it gets. It's a top heavy beast even without a passenger. Her natural parts & single bionic part are making themselves more & more known after a few hours in the saddle. Only stamina issues (so far) I have is typical numbbutt.
Sell the 'Hawks and the ST. Set the CB1100 up w/top box for day / weekend trips.
Upsides & downsides - same as Fence 3. Insurance increase becomes a wash due to fewer bikes.

That's enough for now. The main focus is the longevity considerations & suggestions. Further thoughts welcomed for the talking-to-ourselves portion if the spirit so moves you.

Crossposted to a couple other forums.

Good Ridin'
slmjim & Z1BEBE
 
WOW!! Long post. Good read thanks for sharing.
70,000 miles on a cheap Honda. Nighthawk was a entry level motorcycle price below $4000 new $3995 was the price.
Resale value on a 70,000 mile Nighthawk. Maybe $1000
I did read your post 1 owner regularly maintained.

CB1100EX is the bike I want to get but my 1992 Nighthawk with 15,000 mile and $1500 got the buy!!

Keep riding and enjoy!!
 
Warm-ish day yesterday. Got out on my BlueHawk for 25 mi. or so, long enough to mix Stabil into the topped-off tank. Bike ran perfectly and reminded me (yet again) why we fell in love with the 'Hawks in the first place. Will drain the carbs today for winter. The Ride was also long enough to make me question (yet again) ; Why let go of our '93 'Hawks?
Ancedotal evidence & general consensus is CB750 Nighthawks can reasonably be counted on to reliably be 100K mile bikes, given good care & maintenance.
During our daily hour+ dog park excursion afterward, we discussed (again) what course of action to take. Z1BEBE sez she's happy to keep status quo. That's likely what we'll do. The impetus of stasis, of doing nothing, is strong.
With my future miles as Rider being split between whichever 'Hawk we prep for a Ridin' season, our ST1300A dedicated to two-up, and whichever Z1 we prep for joyrides, shows & charity runs that season, I'd be pushing 100 yrs. old by the time either 'Hawk got to 100K miles, and that only if it & not the other 'Hawk was ridden every year.
Bottom line is, we're happy with what we've got. It was so obvious we couldn't see it.
Thanks for the relatively subjective responses everyone.

Good Ridin'
slmjim & Z1BEBE
 
Sigh…first world challenges. 😀

All seriousness aside, I support your thoughtful decision to keep the Hawks. 👍 Solid, reliable and part of the family!

My ‘03 recently logged 120,000 miles, and other than required maintenance items (I’ve used automotive motor oil!), here’s my DIY repair list since new:

fork seals X2
fuel selector began to leak. eBay
spacers between head and carbs failed. (idle was stuck at 2500).
shift to first with side stand down does not kill engine. (Use center stand!)
transmission gear sensor switch kept neutral lamp on in 1st and 2nd. eBay
ignition switch is becoming wonky. Wiggle!
clutch basket cracked on hard start up steep SF hill. eBay
tach occasionally needs a tap to wake up.
seat foam replaced, new seat cover.
various rubber booties and bits.

I’ll be 80 in February and have ridden little of late, so I’ll be facing decision time come spring.

Ride safe!

”A Rider looks at your odometer & tags.”

Some also look at your “chicken strips”, but that’s pretty much a sports bike thing 😀.
 
In '16 at ages 65 and 62 my wife and I sold everything, including a collection of old Harleys and moved into our motor home. In '20 at age 65 my wife passed away. Last year at age 71 I couldn't stand to be without a bike anymore. I bought a '79 CB750Ltd in remarkable shape with only 20K on the clock. I chose this bike because it was the same model as the last bike I had before we went over to the dark side and started riding Harleys.
I don't ride as much as I used to, that is to say no more 400-mile days but I still find the 2-wheel therapy necessary to my sanity. In fact, got out on the twistys with one of my sons just yesterday.
It encourages me to see a bunch of old geezers like me still doing what we all love. Maybe I'm not crazy after all.
 
Sigh…first world challenges. 😀

All seriousness aside, I support your thoughtful decision to keep the Hawks. 👍 Solid, reliable and part of the family!

My ‘03 recently logged 120,000 miles, and other than required maintenance items (I’ve used automotive motor oil!), here’s my DIY repair list since new:

fork seals X2 - We've run NOJ seal protectors from day one. Still running the factory seals on both.
fuel selector began to leak. eBay - Chinesium knockoff? Fit & reliability?
spacers between head and carbs failed. (idle was stuck at 2500). - Very common on Z1's / Z-bikes. Mama Honda's intake boots are much more robust. We'll get two sets for inventory.
shift to first with side stand down does not kill engine. (Use center stand!) - 10-4
transmission gear sensor switch kept neutral lamp on in 1st and 2nd. eBay - Neutral switch on Z1's were modified from nylon to metal during production. The nylon swatches crack from heat cycles. Are NH switches metal?
ignition switch is becoming wonky. Wiggle! - We had to disassemble a Z1 ignition switch to salvage it electrically, as the lock cylinder matched the key #'s on the rest of the bike; seat & fork locks. We'll get a used one & evaluate if it's possible to do same.
clutch basket cracked on hard start up steep SF hill. eBay - Probably a non-issue for us.
tach occasionally needs a tap to wake up. - 10-4
seat foam replaced, new seat cover. - Hmmm... could be refurbed, or maybe Corbin.
various rubber booties and bits. - 10-4

I’ll be 80 in February and have ridden little of late, so I’ll be facing decision time come spring.

Ride safe!

”A Rider looks at your odometer & tags.”

Some also look at your “chicken strips”, but that’s pretty much a sports bike thing 😀.
Thanks for that response.
We responded individually with our experiences. Please, if you will, advise on the above highlighted & underlined in color. We're in process of obtaining some of those items for maintenance inventory. Long-term planning. Rubber parts especially, as we've seen rubber items on our & other's Z1's / Z-bikes going south from age.

Good Ridin'
slmjim & Z1BEBE
 
Long post to follow. Thinking cap suggested.

We're on multiple fences re: keeping our His n Her pair of '93 Nighthawks we bought new. Both have 70,000+ relatively trouble free, adult touring miles on them. We never wailed on them & they're always garaged. Very well maintained by us. We're Kawasaki Z1 collectors & restoration hobbyists with 40-+ yrs. experience.

We're both over 70. The Lovely Z1BEBE decided to hang up her keys last year, so I pickled her red '93 Nighthawk for long-term storage. My blue '93 Nighthawk needed the carb diaphragms replaced this year, as one was holed. A cheap rack of very-low-mile 750 Nighthawk carbs from fleabay solved that.

I'll continue Ridin'; Joyrides solo on my 750 when the spirit moves me, and Z1BEBE is happy doing the passenger thing on our ST1300A, with a rarel two-up on my Nighthawk, although we'd both like a top box w/ backrest for her.

So, we have two '93 'Hawks, I'm in the autumn of my Ridin' career, and I don't know how many more years I'll be Ridin'. My Ridin' will be split between my Nighthawk, the ST1300A, and whichever of our Kawasaki Z1's we prep for a given season.

Caveat - we're out of room. Garage is full with two vehicles and three bikes, lawn care equipment, and a Honda Hobbit PA50-II moped. The basement shop has six bikes in it. Another one cannot be squeezed into the shop without completely blocking the bike service area. One more bike isn't gonna happen anywhere here at home.

In all cases mentioned below, we keep our collection of Kawasaki Z1's.

Fence 1 - Keep both Nighthawks & prep one alternately each year for maybe, maybe, 2,500 mi. per season. Likely less. This bring up the question of longevity. The CB750 motor is one of the most robust ever manufactured. But, like any machine, there are certain 'high mortality' parts within. "High mortality' is not to be confused with consumable hardware such as spark plugs, chains/sprockets, wheel bearings, brake pads, cables & such.
Upside - We know the model well, know the exact 70,000+ mi. history of our bikes, and have all the docs & most spares we're likely to need.
We have irrational sentimental attachment for our Nighthawks. We've spent 30 yrs. of our 34 years marriage & 70,000 mi. all over two-lane America on them. They mean something to us.
Cost - essentially nil.
Cheap to insure.
Reasonably deep interwebs knowledge base.
Downside - 70,000+ mi. Brings up the longevity Q1 & Q2 questions below.
Not easy to set up for comfy passenger two-up Ridin' + storage due to most accessories NLA.

Q1) We see anecdotal evidence the CB750 Nighthawk motor typically runs trouble-free for 100,000 mi. with good care & maintenance. What sat ye about longevity? Is 100,000 mi. a reasonable estimate based on history of this motor's design?

Q2) What are the (relatively) high-mortality parts in the '91 - '03 750 motor, or the bike in general? Our list so far is:
Turn signals (stalks breaking).
Switchgear, particularly the start switch itself becoming intermittent in the 'RUN' position re: the headlight not always coming on after the motor starts. May be NLA.
Tach. Won't break the bike, but aggravating. Later tachs seem to have solved the problem. We have a late NOS tach on the shelf just in case.
Valve cover gaskets. We replaced both @ ~50,000 mi. or so due to slow weeping developing. Easy.
O-rings at the fuel 'T' & junction pipes. Easy.
Petcock - one failed years ago. Leaked in the 'OFF' position & motor went into hydraulic lock. Rebuild kit failed. Replaced with new OEM. Not exactly high-mortality, but still...

That's about it for our high-mortality list. Any suggestions, parts we've missed?

From here down we're mostly talking to ourselves. It just helps to see things in print sometimes for thoughts to jell. We're most interested in the above. Feel free though, to chime in on how you've managed similar considerations.

Fence 2) Sell both our 750's & replace with one, nice, much-lower-mileage '91 - '03 Nighthawk. They're out there.
Upside - much newer bike we're very familiar with, & have the service manuals & some spares on the shelf.
Still cheap to insure.
Downside - We have irrational sentimental attachment for our Nighthawks. We've spent 30 yrs. of our 34 years marriage & 70,000 mi. all over two-lane America on them.
Unknown history.
Not easy to set up for comfy passenger two-up Ridin' + storage due to most accessories NLA.
Cost.

Fence 3) An friend & fellow vintage bike resto hobbyist has a one-owner, low-mile (800 mi. !) 2017 CB1100EX for sale. We sell both 'Hawks, replace them w/ the CB1100 set up w/ top box/backrest.
Upside - Much newer bike. Current OEM parts support. More power than any 750.
Can easily be set up with a top box using currently-available rack & box for backrest & storage for short two-up day / weekend Ridin'.
Known history of this CB1100.
Reasonably deep interwebs knowledge base.
Downside - We start from scratch on parts stock, documentation and a learning curve of a different, much more complex (ABS, fuel injected) bike.
Spoke wheels (tubes) & uncommon tire sizes.
Also, irrational 'Hawk attachment & etc.
More expensive to insure.
Cost++

Fence 4) Realistically, how many more 3+ week, 2,000+ mi. tours are we likely to do on the ST1300A? The older I get, the taller & heavier it gets. It's a top heavy beast even without a passenger. Her natural parts & single bionic part are making themselves more & more known after a few hours in the saddle. Only stamina issues (so far) I have is typical numbbutt.
Sell the 'Hawks and the ST. Set the CB1100 up w/top box for day / weekend trips.
Upsides & downsides - same as Fence 3. Insurance increase becomes a wash due to fewer bikes.

That's enough for now. The main focus is the longevity considerations & suggestions. Further thoughts welcomed for the talking-to-ourselves portion if the spirit so moves you.

Crossposted to a couple other forums.

Good Ridin'
slmjim & Z1BEBE
I'd absolutely keep at least one of the 750 'Hawks. Mine's a '91 ("Tokyo Rose" - all the '91s were red). I'm two years older than you and I TOUR. Got her used in 2012 with just 19k miles on the clock. Just hit 84k, still running like a Rolex and, like one of yours, the only non-consumables I've had to replace were the valve cover gasket and fork seals - which had "disappeared" from sitting unused in a damp storage shed for about 17 yrs.

It was the original owner's last bike. He had "aged out of" riding and simply put the bike away in '95. His son (not a rider, didn't live there) finally put it on Craigslist in 2012 for $900. I grabbed it!

Engine compression tested great. Tires and other rubber were pretty shot. I replaced them, also most of the wiring, the sprockets, chain, and seat cover. I was lucky. Although covered w/dirt and dust, she was in amazing cosmetic shape. And Rosie had originally been delivered with all of the "options" - both of them: 1.) the center stand and 2.) the one-piece sissy bar / rear luggage rack. The transmission's still shifting solid, and the tach still works like new. Oh, and I replaced the original clutch @ 40k mi. (another casualty of sitting in the shed for all that time, half in and half out of the oil?)

Set 'er up for touring with an eye-high, NATIONAL CYCLE Windshield-Fairing, and a 6 gal. waterproof, backrest-trunk on the pillion. Feels like sitting in a 1-place Cessna. She'll still do 80 all day w/out complaining or using oil, while you're getting 48 mpg, and, if you want to, she'll get the speedo up near an indicated 120 mph.

And, Oh Yeah, the question about longevity ;o)) The way the engine-tranny pull and sound @ 84k miles (like new), I'm thinking that 110k is probable before any major surgery is needed - if even then. Whether I'm the last one standing, or whether it's Rose, that's really the question.
 
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Inspiring....stumbled upon your post while looking for a replacement tail light. I have a 97' Nighthawk. I love it, the only complaint is it gets a bit shaky after 200ks [120mls?]. No idea what that means.....I don't know how I happened to get it, as I live in Australia but my bike was a Nighthawk built for the Californian market. It did have state of the art emissions control...it did....but it's great, just a great reliable city bike. Anyway, I'd keep at least one if I were you, but then I'm probably unnecessarily sentimental.
 
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