Lovely looking XZ400 cafe racer for sale in NZ

Started by pinholenz, September 18, 2016, 11:22:23 PM

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pinholenz

While this listing is current, you might like to have a look at this sweet cafe conversion. ( I haven't quite worked out how the bars dont slap the tank yet). De-seamed and shaped tank looks great- a bit like a Norton Commando tank.

http://www.trademe.co.nz/a.aspx?id=1164960744
Only one '82.5  eXtreme Zen 550

Rikugun

They're not bashful with the price but it's pretty nice. It appears to have a "radial pump" master cylinder mated to what looks like stock calipers. I wonder how that feels?
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

pinholenz

I'm hoping to get down and have a look at it if time allows.

To give you an idea of NZ prices, an incomplete parts XZ would be about NZ$200, a de-registered runner about NZ$700 and a not so special road-worthy bike around NZ$1600. His starting price isn't too bad given the Kms, but after that it will come down to market demand. It would be more attractive if it were a 550 but you need a full license to ride them here. The power to weight ratio of a 400 means that a learner can ride them. This would be a very pretty bike for a learner! I'll be interested to see where it goes. There  are active Japanese Vintage Clubs in NZ. Since all our bikes are imported, we tend to be a bit less sniffy about real bikes being only BEA's.
Only one '82.5  eXtreme Zen 550

Rikugun

Thanks for the insight, that helps although I'm a bit unsure of what a BEA is?
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

pinholenz

BEA, British European and American. A popular racing class over here is BEARS Racing, especially for classics. Basically non Japanese motorcycle racing  for those who like the sound of thunder but don't want the undesirable side effects of speed and agility. (Only half joking!).

What's the most efficient way of turning petrol into noise without the undesirable side effect of power? A Harley
Only one '82.5  eXtreme Zen 550

pinholenz

FYI Rikugun, the seller of the bike tells me that it is a 19mm bore on the new brake master cylinder, same as the original.

The final auction sale price was NZ$4,000 which is about US$2900. I am delighted for the seller and the new owner.
Only one '82.5  eXtreme Zen 550

Rikugun

That's a good price for the seller for sure - the market is quite a bit different here in 'merica. Speaking of the home of the brave, the twin disk USA models came with a 5/8" master which is just under 16mm. Assuming the 400 has 38mm calipers, I'd think the 19mm master would make for a wooden lever feel. The only caveat is I have zero experience with that style master and perhaps it's mechanical advantage more than makes up for the seemingly horrid 8:1 hydraulic advantage.
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

pinholenz

I have to confess I haven't a clue about the relationship between master and slave cylinder sizes and the effect these may have on braking feel and performance. If you can point me to a "Theory 101" tutorial I would be grateful!
Only one '82.5  eXtreme Zen 550

fret not

Retired, on the downhill slide. . . . . . . . still feels like going uphill!

pinholenz

Great link thanks. I am starting to get the idea.

However on the chart, I cant quite figure out how the ratios work. The text recommends somewhere between 23:1 and 27:1 or thereabouts.

For a single 38mm caliper with a 1/2in master cylinder the ratio shows as 8.5 on the chart. (US single disk)
For our 2x 38mm calipers and 5/8 master cylinder bores, the ratio shows as 11.28 on the chart (NZ twin disk)

In theory these sort of ratios that are standard on the XZ, should be unusable for progressive braking. What am I missing?
Only one '82.5  eXtreme Zen 550

Rikugun

#10
The link fret posted won't load for me right now but I'd guess the ratio's in the 20's are for modern sport bikes with radial pull masters and multi opposed-piston radial mount calipers or racing applications - not vintage bikes. Conventionally mounted calipers would likely flex wildly at those numbers. There are safety concerns as well in that a brake made for track use would likely flip the bike over if a handful was grabbed in a panic situation at moderate speeds. The spread sheet I made shows numbers like you discovered - 9 and 11.5 respectively for the single and twin disk XZ's. The single disk in particular is really awful and the twin disk could be a whole lot better.

For a vintage setup like the XZ with single piston (or one sided 2 piston) calipers and conventional masters I think 12-14 to one is probably a more realistic goal and can make for a strong one or two finger brake. From my experience mid to high 14's are better. For twin piston opposed calipers you can get away with slightly higher ratios.

Keep in mind this considers the hydraulic ratios only and doesn't consider number of rotors or their diameter, pad material, lever pivot length etc. but this rule of thumb seems to hold up for bikes I'm familiar with.
It is far better to grasp the universe as it really is then to persist in delusion, however satisfying or reassuring.  Carl Sagan

The Prophet of Doom