Spent a while measuring things today and realised I made some mistakes on the calculations yesterday. Here's what I tried today:

Standard setup (forks flush with top yoke, rear axle in the middle of the chain adjument range): 

• Rake: 22.5°
• Trail: 89mm
• Swingarm angle: 11.3°

Forks dropped (forks sunk 10mm into top yoke, rear axle in the middle of the chain adjument range): 

• Rake: 23°
• Trail: 92mm
• Swingarm angle: 11.6°

Lowered back end (forks flush with top yoke, rear wheel raised 35mm towards frame): 

• Rake: 24.5°
• Trail: 100mm
• Swingarm angle: 8°

All this means that I can't lower the back end or my swingarm will be too flat - makes it easier to deal with the shocks, don't need to move the mounts anymore. My only option is to raise the front end. Here's what I've though of so far, suggestions are more than welcome:

• Put a spacer in between the fork damper and the fork lower to lengthen the fork. Not sure how much I could gain with this before I start to lose stability in the forks, maybe 15-20mm and chuck a fork stabilisor on?
• Find some 43mm fork uppers that are longer than the ZRX's. No idea where to look though...
• Drop the forks in the top yoke - can get about 9mm out of this before going past the top clamp bolt. Would need some covers for the tops of the forks though - it looks pretty sh**. 
• Get new triples with a 30mm drop - really don't want to do this  
• I can probably get about 5-10mm if I play around with static sag once the bike is assembled.

Any other ideas?


Forks dropped in the top yoke:
 

Rear end lowered so the rake/trail is good - swingarm is too flat:
 

Had a bit of time today and got the wheels on. Checked rake and trail and without changing anything I'm at 22°and 94mm. I crunched the numbers and if I can raise the back by 7-8mm I'll end up with 25° and about 107mm trail. Slightly more trail than the ZRX but I have 10mm of adjustment in the shocks. At the moment I can go about 3mm shorter and 7mm longer so I'll probably centre them and lift the back wheel by about 7mm. Then I should have a decent range of adjustment in both directions. I haven't checked the swingarm angle yet (a job for tomorrow) but it looks a bit steep so lifting it up a bit should be fine.

 

  

  

While having the valve cover off to check the valve clearances, I also replaced some of the rubber bits while in there.
Had an extra cylinder head, so checked what shims were in it, and was able to use a few;

ZRX1100 rear shocks on.
They are about two inches longer than the Konis currently on there.
I will bring the front end back up to stock level, as I've had the forks slid up in the triple trees for ages.

 

Part of the project this past Winter was installing a set of Keihin CVK32 carbs off a ZX600 Ninja.
I bought the carbs thinking they were ZR7 carbs, which was what's needed.
Thankfully the ZX600 carbs are the same size.
I followed Pablo's/z650Spirit's tutorial on installing the CVKs.

Also will use the stock ZRX shocks I have.

VM24SS carbs and air box removed.

@DoctoRot: Good info - thanks That will make it a bit easier to figure out where to put the mounts. The shocks are for the ZRX1100, so I'll use that geometry as a template. EDIT: I'll get some numbers for the swingarm tomorrow.

@750 R1: Thanks for the numbers - you posted at the same time as I did

Getting back into things again. Put the stock forks and swingarm on today to check th height. Raised the frame of the floor and measured from the floor to the centre of the wheel axles. Will make it easier to check if the nose is dipped with the new triples and ZRX forks. One problem though: the shocks that were on the bike don't look stock. Can anybody tell me the length of the stock shocks on the KZ1000A1? Just want to make sure my starting point for the frame angle is stock.
The modified GSX-R swingarm and Öhlins shocks arrived yesterday. I'll be chopping a few things off the frame tomorrow so I can get the swingarm mounted (brake pedal bracket needs to go). Once that's done I can get the ZRX forks back in and check the height of the front and back axles. If I'm lucky the bike will be level at the middle of the height adjustment range on the shocks.

 

I'm skimming through the last years worth of work, so things didn't as quickly or smoothly as it seems.. Early last year, I could finally mock up the rolling chassis having been given a pair of 41mm forks of the right length (they need rechroming so weren't worth much). I found the billet yokes on my mates workshop shelf where they'd sat unused since he made them a decade ago. Waste not, want not...

By todays standards the forks a little spindly at 41mm, while the yokes are equally modest. They may be replaced with something better, but for now they'll have to do.



The top yoke was drilled to take the risers, all the spacers and engine bolts/brackets have been made.. the bolts being made from 316 stainless. I spent far too much on a pair of remote reservoir shocks by K-Tech. They are built to the spec of a ZRX1200 (365mm) but with slightly softer springs, as the bike should be lighter than a standard ZRX, while its unlikely it'll ever carry a pillion.

The white cardboard over the drive sprocket is just to give me an idea of the size of alloy plate needed to make the outrigger bearing support.




The Z1 side panels and tail unit arrived, they are very well made, come from Japan I think. Sadly and not unexpectedly the tail piece wont fit on the now widened frame. I was hoping the tail unit would have some flex so it'd go over the seat rails, but no chance. 

If the tail piece had been made from fibreglass I'd have been tempted to cut it in half and widen it to fit, but its made from ABS and its too nice to cut up in any case. Instead I bought a cheaper fibreglass Z1 tail piece, and promptly cut it in half. It fits ok when the two halves are angled in the pic below, but not sure yet what the best looking option of positioning them before I fibreglass them back together.

There are a few unexpected problems with trying to fit early Z1 bodywork on a 650 frame, one of which is that the fuel tap will have to be moved forward as it hits the longer Z1 side panels. I thought the tank was from a Z1000, but it seems its from a Z900, which have a different petcock position.

Meanwhile the inner plate for the outrigger bearing support is almost done, its from this plate that the outer plate (which carries the support bearing will be mounted from, via stand off spacers. This outer plate will also be used to mount a clutch slave cylinder to convert from cable to hydraulic clutch. 

DoctoRot wrote: Don't forget the stock kz triple has about 1.25" of drop .

Other considerations down the road for the ZRX forks is a fork brace, and have the forks tuned. I found the stock valving and springs to be kinda harsh on mine. I recently had them reworked by Matt Wiley at Racetech with new springs, compression gold valve, and HFR rebound valve and it rides sooooo much better. Way less skittish during WOT, and much better road holding in general.

Thanks, I took the drop into account. With stock setup the top of the forks end up being about 4mm above the lock nut under the top yoke (4mm at 26°). The offset is about 60mm. With my setup the forks sit about 30mm above the lock nut and they have about 33mm offset. The forks are about 7mm shorter than stock as well.

Got new linear springs on the way. Wasn't sure on the brace, would have definitely put one on stock shocks. Will look into it again and have a look at the valve options over here.

OK, I've been doing some research and taken the advice given here. The current plan is as follows:
Engine:
- Wiseco 1075cc piston kit (w/ welded crank)
- bigger valves and ported head (letting the engine builder do his thing here - 38mm intake valves)
- WEB CAM Stage 2 cams ("hot street")
- RS34's
- K & N pod filters

Chassis:
- Shorten the back end. Keeping the original tail but moving it forward so I end up with a single seater. Chopping off the pillion footrest brackets.
- Frame bracing
- ZRX1100 forks and brakes with a new front wheel hub to fit (getting a triple clamp made for the conversion)
- 110 front wheel, 160 rear wheel (spokes)
- GSX R750 swingarm
- Öhlins S36PR1C1L rear shocks
- minimized front end (smaller speedo and tacho, headlight, clip-ons).

Before anyone goes too mental about me chopping up the frame - I got a second frame for cheap as the pillion footrest brackets are rusted and someone's been cutting things off the back end. Will use this frame and keep the original one in storage.

A couple of things I'm not sure on:
- I'd like to do away with the battery and just use the kick-starter. I've read that this works with the Tarozzi rear-sets but I'm not sure how practical it will be. Are these things a pig to kickstart?
- Earls oil coolers are crazy expensive here. Does anyone based in Europe have any recommendations? The engine guys stock Setrab coolers and one of them will cost about half as much as an Earls cooler.
- Does anyone have any gearing recommendations or should I stick to the stock 15/33?

When I tally up everything that I'm replacing, I'll be left with a frame, triple clamp, forks, swingarm, front wheel, rear rim and spokes (no hub), front and rear brakes incl. master cylinders, switch blocks, levers, side covers, carbs, footrests and a few other things. Basically, I'll almost have a second bike minus the motor. I'm considering just getting a new hub for the rear wheel and keeping the old one as a spare (and keeping my eye out for a motor). I could use the 'spares' bike to help finance the project. Any recommendations for another model that I could pull a spoked rear wheel and swingarm off? I thought about a Zephyr but the 1100 swingarm is supposedly heavy and I don't like the idea of the excentre for setting chain tension.

slayer61 wrote: While I'm here, I might ask about gauges as well. The OEM are gawd awful & very knackered. Suitable replacement options would be gratefully considered.

Oh....where do I start.....

As you saw my 81 gpz11, I've done a bunch. My recommendations below.

1. Gauges..they were butt ugly..I replaced mine with a set off of a 85/86ZN750, bolts right up and looks great. I would also look at the KOSO as well. If you use the triple clamps from this bike, you don't have to mill the GSXR 18" front brake hub mounts down to clear the forks. They are ~1.2 inch wider and 38mm.

2. Brakes, trash those stockers, they suck butt, I bought a set of CBR600F3's complete for $20.00 and they are perfect. One finger stops, using the stock brake master.

3. See my suspension upgrades...if you plan to keep the stock shocks...which are worthless stock form. Short list, RaceTek Emulators and Springs, better oil, 10psi.

4. Rear shocks, any decent upgrade, Ohlins are expensive, and seem to need frequent overhauls. I like the ZRX units and they are cheap.

5. Trash the stock rear swingarm, again, useless piece of wet noodle.

6. Wheels are a personal thing, I like wider rubber, so I upgraded mine. 17" or 18" (GSXR) etc...

7. I never could get my FI to work so I trashed it...I still have some left overs too...and went with Mikuni RS34's with pumpers. LOVE THEM.

8. Ignition, trash the stock one, it's too old now, get a full Dyna with everything, you will be amazed how much better the bike will run.

9. Stronger and stiffer engine mounts, stiffens the frame, better handling.

10. Rear Sets? personal thing..

11. Mandatory in my book, high quality steering dampener, will save your wife's life one day...

Just to start you off.....

577nitro