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Discussion Starter #1 (Edited)
My wife will kill me, but I'll die with a smile on my face doing this project !

Here's the current Z before getting the chop... clean & fresh with a CRF70 front plate on board.



The parts I'm gathering/gathered:

RM65 Triple Tree.
KTM 50 SX PRO JR Front Forks - Hydraulic 32mm fork, 140mm (5.5 in) travel.
+14cm Monoshock swingarm, shock not yet determined (Fastace or even an R1 will be looked at.
China - Front alloy disc brake hub adaptor & Disk rotor.
KTM 50 SX PRO JR aftermarket brake assembly (caliper/hydraulic hose/perch & Lever).



Watch this space if you thought the XR50 turned out pretty good...



Won't be a quick build as the parts will come from all over the world, but watch this space !

Darrie
 

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Discussion Starter #3 (Edited)
Keeping the 8" treads.... and partial to the white rims ... even thinking of upgrading to 8" alloys and getting them powdercoated white. Sorry these are early Rm65 headset (post above amended), had these for a while and appear to be wide enough with a little milling on the hubs.

I'm going to do a mock up with paintshop so you can all give me a thumbs up or down on the proposed look.

Keep an eye out for an update shortly.
 

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What disc are you going to use on that hub, only one I could find for the bolt pattern was a 155mm od. The tbolt +3 with the 330mm shocks works great if your looking for long travel in the rear.
 

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Never mind your going mono shock. I have one of those china(eBay) Cnc front disc hubs I don't think I'm not going to use if your interested.
 

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Discussion Starter #6 (Edited)
Well here it is - a very non-artists impression on where I'm heading. Possibly will be more downward angle on the swingarm, all depends on how the forks turn out. What is everyones opinion ?
 

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Discussion Starter #8 (Edited)
Totally agree a shorter swingarm would be best to reduce the wheelbase (hence why crf's have shock laying over arrangement), but problem is upright shock naturally has a longer swingarm and gives more travel.

My drawing may not be exact to scale and it may turn out shorter, but wanted to look at worse case scenario when I was drawing it up ! Japanese monoshock swingarms appear to be really long, designed for big rubber and road use. I've sourced +14cm swingarm out of the UK. My goal was get one with a lower mount so that I could be more flexible with shock lengths and the upper mount location as I'm not using the small shock and bolt on mount.

This is what I've ordered (upside down image):

58.jpg


Worse case scenario is that if I bail on this swingarm and want shorter I may have to fabricate a lower shock mount on a swingarm out of China... they are pretty cheap, and they look to have plenty of support material in the right spot.

There are some real issues when the swingarm grows in length .... the center of gravity moves forward, the turning radius is increased (so turning slower), weight transfer forward on braking is reduced and the rear brake does more work. Weight transfer backward and traction on acceleration are also reduced, but all this is partially counteracted by longer forks.

I'm also conscious that the Z has never been a fantastic turner in stock form - I may be making it worse with more trail from the new forks. Overall it's a design nightmare, but having the XR working so well I'm giving it a go !!! I've learnt building in adjustment flexibility is the key ... being able to raise & lower fork tubs in the headset, change rear shock lengths all makes tweaking the handling much easier.
 

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Looks like a pretty cool build mate. I'm also building a mono shock Z for something different. Anymore progress on the build?
 

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Discussion Starter #10
The good news: Forks arrived - in nice condition and action is smooth, but one leg had zero dampening ! Ebay Picture was exact, but description about the pair in perfect working order was only 50% right !
Marzocchi forks.jpg

I checked & it had oil. Quick research on the net and problem identified - dampening Piston ring for rebound gone. Was pleasantly surprised the part was easily available for only $7.60 ... lucky. They look perfect length for the project and are very tidy.

Now the challenging bit: Forks look identical to the Paioli Meccanica ones I put on the XR50, but at 32mm are few mm smaller. The triple tree I was planning on using was initially purchased for the XR/Paioli Meccanica fork combo, but I ended up not using these as the whole front end on the CRX50 was swapable that was the easier path. Choice now is to sleeve this for the smaller forks, or look for potential new donor triple tree. Using the RM tree will require about 10mm shaved from each side. Possible trip to the local parts recyclers first before embarking on squeezing the tyre into this 20mm narrower headset. Will keep everyone posted.
 

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Discussion Starter #11
*** Triple Tree Update ***

Well that was challenging finding a nice wide forward facing tree to support 32mm fork tubes. Scooter places seem to have the best choices as traditionally they run wide small fat tyres similar to the Z50's.

I've ordered these from fancy scooters. (from a 125 chinese dirtbike model GS-114 ).




A tight squeeze, but nice forward pattern to help clear the tank. KTM headset is just too straight. Centre shaft will need shortening and milling down. A bit of work for the fabrication shop no doubt.

In hindsight probably more 30mm & 33mm donor triple trees available, just not as many nice forks of a small size and bloody hard to get measurements off anyone. Prefer a Japanese tree but settled on this. Waste of $ or a good solution ... not sure yet, but down this path I go !!
 

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Discussion Starter #12
Update .... Last parts needed ordered. Alloy front disk brake hub, 155mm rotor and settled on a used 2003 cr85 front caliper and brake assembly that will need grafting on... know at least going to have to change the brake hose as its way long than my requirements. I'm excited & a little worried about if it will all fit together. Fork and tree combo looks sic !

The rear will be long, so I'm trying to source a carry rack for the Z50R to balance the rear up... that's proving to be a challenge also, but a friend of mine does custom allumininum fabrication and thinking that will be the ticket.
 

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Subscribed looks nice
 

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Discussion Starter #15 (Edited)
Well where are the pics!
I'm hearing you !!!! ... this will be the first weekend I've been home in the past 3 weeks (been camping every weekend). I've got plans to be on the wrench/camera/pushing the mower & a bit of chainsaw work courtesy of a tree fall !

Update today ..... Holy Crap !!! Ordered the disk rotor & hub from China on the 29th of October on Ebay, and it arrived today the 1st of November. Unbelievable - 4 days to deliver. Just shows how many flights are coming direct from China to Cairns bringing tourists (and my bike parts).

Even better I can assemble up a mock up front end this weekend.
 

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Discussion Starter #16
ok a teaser..

Forks in the Chinese triple trees - using bolts I could find at this stage

P1050232.JPG

The dampener with the missing piston seat
P1050233.JPG

Totally surprised ... all the headset is a complete bolt up to the Z50r head tube with no modifications. I'm sure the rest isn't going to be as easy.
P1050237.JPG


P1050238.JPG
 

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Discussion Starter #17 (Edited)
*** FRONT UPDATE ***

Gorgeous weekend here, but I squeezed in a few hours to do a front end mock up.

Skyteam Disk hub a nice fit, though appears set up for a 4 bolt pattern rim, my z a three bolt pattern with studs already in the hub. Not a hard thing to fix.

Ample clearance for everything, simply a matter of machining spacers to centre the wheel. Fitting a brake caliper will however be interesting !

OEM Axle is about 20mm too short, substitute will be needed.

No rear swinger installed yet so chocked up rear, but you get the concept.

There was no discernable difference between the front and rear before the hydraulic forks, however now the rear feels like its rock solid compared to the front.









 

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Discussion Starter #20
Just an update .... Not happy with the +14 swingarm - whilst suited for an upright shock, not suitable for a laying forward arrangement. I was surprised it didn't look as bad as I thought it would as long as the swingarm was pointing down - if swingarm was level it looked tragic !!!!.

Now gone to a DHZ Heavy duty swing arm for $75 (at a guess +10cm on the Z swinger) and modding the 12mm swingarm bushes to deal with the smaller swingarm bolt size. Swingarm also had the mounts for chain guide etc which is a bonus, and local shop has parts galore which I can test if they fit. Actually looks nice.



I was blown away that the Pitsterpro bike is so near a replica of the 50 frame that I can even steal their frame idea to replicate the rear upper shock mount setup and support braces (they run 2 either side - its not often you can steal an idea from the Chinese !!!!!

I'll post up pics over the next few days and a few accurate measurements, but here is the "Donor" Bike. Swingarm rear opening was wider, so some spacing will be needed but not much !




 
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