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AV80R ZX-4RR build thread

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Discussion starter · #563 ·
lunarx said:
So cool to have both of those. 😎
Would be very interested to hear your thoughts on how they compare.
Click to expand...
Just had an "aha" moment and realized you are asking about how the ZX-7R and ZX-4RR compare (not the ZX-4RR 40th vs the KRT).


In short, they are so totally different than each other there is no way to really even mention anything between them in the same breath.

The ZX-7R K1 was a homologation bike built in very limited numbers to allow Kawasaki to take it racing.

Only 142 were brought into the USA, with worldwide production in 1991 at only 500 units.

The R version featured Keihin flat slide carbs, fully adjustable suspension, an aluminum fuel tank, lightweight aluminum subframe with solo tail, and special gearing which had a very long first gear.

All of that was a great basis for building a race bike, but made for a terrible street bike. Particularly bad mannered were the flat slides.

Unlike the CV carbs of the standard ZX-7 which you could whack open at any rpm and they would only open the slides exactly the right amount needed based on engine vacuum, the flat slides had to be nursed with throttle openings correlated to the engine rpm. Meaning you can't open the throttle all the way until the rpms climb. Once in the power band, the throttle becomes very touchy and was extremely responsive.

The super long first gear makes all that carb business even more daunting. This isn't a bike that an inexperienced rider hops on and is able to operate out of the gate.

The bike feels very planted in corners and with the best tires of the era, it was known for how well it held a line when leaned over. Very stable and confidence inspiring, it begged you to go fast and flick it side to side with ease.

The whole experience was raw and unfettered by any electronic nanny's for acceleration, braking, or cornering. In contrast, on the ZX-4RR with KTRC and ABS active, you are just a voting member and the bike decides what to do. The ZX-7R does exactly what you tell it, even if you're asking for the wrong thing!

The fit, finish, and feel of the ZX-4RR feels light years ahead of the ZX-7R. A lot has changed in 30+ years and the ZX-7R was built in the early days of the Superbike revolution to crawl out of the dark ages of the 1980's.

The RC30 Honda, YZF-750 Yamaha, and GSXR-750 Suzuki were all in their infancy right around the same time as this Kawi. They were advanced and fast for the time, but there was still a long ways to go before they evolved into the modern era motorcycles we know today.

It's still one of my favorite bikes, and although they have climbed in value, they still haven't reached the levels commanded by the Honda RC30, so relatively still a "bargain".

1991 Kawasaki ZX-7R K1 – Iconic Motorbike Auctions

Fort Myers, Florida - Kawasaki's iconic homologation special, offered with its original tank and body panels. True mileage is unknown.
iconicmotorbikeauctions.com iconicmotorbikeauctions.com
 
#571 ·
AV80R said:
Thanks to you for the heads up on JetPrime. I had no idea they existed until you showed me. I requested it without the logo when I placed my order.
Click to expand...
No worries! A small token for all the things I learned from you.. I got them for the Panigale as well.. One thing that worries me now, that I haven't checked on before, my right side looks weird.

Image


I wanted the ride by wire. I don't remember now how my left side looked like. If its black and doesn't match the right i got a problem. Haven't unboxed the other side yet. I'm back at the shop on Friday, lets see how this mystery ends up.
 
#574 ·
AV80R said:
Just had an "aha" moment and realized you are asking about how the ZX-7R and ZX-4RR compare (not the ZX-4RR 40th vs the KRT).


In short, they are so totally different than each other there is no way to really even mention anything between them in the same breath.

The ZX-7R K1 was a homologation bike built in very limited numbers to allow Kawasaki to take it racing.

Only 142 were brought into the USA, with worldwide production in 1991 at only 500 units.

The R version featured Keihin flat slide carbs, fully adjustable suspension, an aluminum fuel tank, lightweight aluminum subframe with solo tail, and special gearing which had a very long first gear.

All of that was a great basis for building a race bike, but made for a terrible street bike. Particularly bad mannered were the flat slides.

Unlike the CV carbs of the standard ZX-7 which you could whack open at any rpm and they would only open the slides exactly the right amount needed based on engine vacuum, the flat slides had to be nursed with throttle openings correlated to the engine rpm. Meaning you can't open the throttle all the way until the rpms climb. Once in the power band, the throttle becomes very touchy and was extremely responsive.

The super long first gear makes all that carb business even more daunting. This isn't a bike that an inexperienced rider hops on and is able to operate out of the gate.

The bike feels very planted in corners and with the best tires of the era, it was known for how well it held a line when leaned over. Very stable and confidence inspiring, it begged you to go fast and flick it side to side with ease.

The whole experience was raw and unfettered by any electronic nanny's for acceleration, braking, or cornering. In contrast, on the ZX-4RR with KTRC and ABS active, you are just a voting member and the bike decides what to do. The ZX-7R does exactly what you tell it, even if you're asking for the wrong thing!

The fit, finish, and feel of the ZX-4RR feels light years ahead of the ZX-7R. A lot has changed in 30+ years and the ZX-7R was built in the early days of the Superbike revolution to crawl out of the dark ages of the 1980's.

The RC30 Honda, YZF-750 Yamaha, and GSXR-750 Suzuki were all in their infancy right around the same time as this Kawi. They were advanced and fast for the time, but there was still a long ways to go before they evolved into the modern era motorcycles we know today.

It's still one of my favorite bikes, and although they have climbed in value, they still haven't reached the levels commanded by the Honda RC30, so relatively still a "bargain".

1991 Kawasaki ZX-7R K1 – Iconic Motorbike Auctions

Fort Myers, Florida - Kawasaki's iconic homologation special, offered with its original tank and body panels. True mileage is unknown.
iconicmotorbikeauctions.com iconicmotorbikeauctions.com
Click to expand...
Amazing Comparison 🤩

Although it’s irrelevant, would the humble ZX-4 w/ half the cc of the ZX-7R be faster/slower/similar on a track?
It’s always nice to hear when one can get more done w/ less (if thats the case) 😉.

Not that I’d ever buy or ride a ZX-7, because I’m far from that experienced rider who could handle it.
 
Discussion starter · #576 ·
The @Gravesport aluminum throttle housing is superior to the JetPrime aluminum throttle housing. Just by looking at the Graves drawing I can see a couple design features that are missing on the JetPrime one.

1. Graves has duplicated the mechanical stops from the stock housing into their design.

This has two consequences. First, the JetPrime housing relies on the throttle sensor's internal mechanism to limit the movement of the tube. This works but is not ideal since the second consequence is that without a travel stop outside of the sensor built into the housing, the negative travel at idle is back and there's no way to get rid of it even though I'm using the Graves aluminum throttle tube that relies on an external stop in the housing to work.

2. Graves has provisions to secure the throttle sensor to the housing using two self tapping screws. Although the JetPrime housing holds the sensor in securely, it's a friction fit which relies on both halves of the housing to sandwich the sensor securely.

Image


The sole item on the JetPrime housing which is really nice is having the switches integrated into the throttle housing.

I may have to think about what my next move is, but I can't recommend the JetPrime throttle housing based on these shortcomings. Does it work? Yes. Is it optimal or ideal? Not really. 🤷🏻‍♂️
 
Discussion starter · #578 ·
I would love to but that leaves me with a problem of no right switches.

Image



The 3 button switch integrated into the JetPrime housing aren't available separately (that I know of).

Chuck's bike has some switches that replace the clamp for the Galespeed master, but he has way more buttons than 3.

Image
 
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