An upgraded & modernised GPz900r but keeping it all within reason and maintaining the original design lines of the bike.

Of grat interest was the upgrades – installation of a 973cc kit – googling shows you can still get Wiseco 972cc kits – but japan.webike now suggests that big is a bad idea as there are no longer any stock Kawasaki cylinders?.  Hmm.  Not something I would do just because, but when my engine does need a rebuild maybe split the difference and go forged pistons.

The ZX-10 rear wheel takes the rim width from 3.5 to 6 and probably a 190/55/17 tyre – which is a massive increase in width and only ~30mm reduction in diameter, so the side profile of the tyre and the bike still looks similar, especially with the modified swing-arm from ZX636 design still looking close to original.  The bigger tyre also will have a bit more give in it, hopefully softening up the ride a tad without compromising handling. Seriously good and sympathetic upgrades IMHO.

I contacted Per.N at Wrenchmonkees who helpfully provided a bit more info on the mods.

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Ian B. is a member of Kawasaki GPz900r Owners and in 2015 MCN did a really nice write up of his A1. He also takes some fab photos of the old girl as well!

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Crikey – a GPz900r I think!  A feel a bit like looking at a ‘Where’s Wally’ illustration…..with a Honda Civic rear wheel – lol!  Anyway I think the name says it all (grin) and no matter whther it’s to your taste or not – it’s an absolutely outstanding effort!

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Another very cool cafe racer rebuild from the crew at Mafia Moto Crew Germany. Click the link for their FaceBook page full of amazing stuff.

Technically it would be interesting to know how the bike handles at low speed (it’s a cafe racer!) and if the modification to the rear has actually increased the wheelbase or is that just an optical illusion.

Also good to know of a link to a local (German) 4-1 exhaust supplier, and it’s nice the way it all terminates before the rear wheel,  IMHO anyway!  However I’m not convinced it would fit under the fairings……

What was interesting was that one of the reasons they chose the GPz900R was because you can easily remove and replace the rear sub-frame because it isn’t part of the main frame nor is it permanently connected. From what I gather you aren’t allowed to modify any welded frame (load bearing or not) in Germany, so that likely really limits the bikes you can modify.

I can see the pros and cons of this rule and it does raise an interesting discussion on major motorcycle modifications.

Whilst we are all backyard experts and many of us may have related mechanical skills, I doubt many of us are motorcycle engineers nor do we have access to FEA (Finite Element Analysis) to prove the engineering of modifications. I can also speak from experience in commercial boats where you simply can’t modify anything structural without significant documentation and analysis.  And I also understand the difficulty in engineering welding – there’s just so many variables its almost impossible to accurately document with old frames.

So maybe rules that ensure the original parts aren’t modified aren’t such a bad thing, and I can understand why authorities have them in place – no matter how frustrating that might be to custom builders.