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Author Topic: The z50 Zombie, Back from the Dead - a Honda Mini Trail resurrection  (Read 627 times)

Offline advCo

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As most of you know, I have a bit of a soft spot for the funky, oddball, small displacement bikes that were coming out in the 70's. I've been looking for a 50cc version of one for a couple years now, either the z50, MT50 trailhopper or what have you. While doing some window shopping on CL, I spotted this poor, insanely abused example of a soft tail z50 - a 78 to be exact, and probably my favorite generation of these bikes style wise. I'm starting to feel like the ASPCA for motorcycles. This thing should probably be put out of its misery, but I'm going to bring it back from the dead.

The guy had it listed for an outlandish price, so I offered him pennies on the dollar and we eventually made a deal. I met him on my lunch break yesterday, picked up the turd and then promptly broke it down once I had it in the shop.  Amazingly, the motor still turns over despite the busted up case covers (easily replaceable), nothing is seized up and even the brakes still work. It came apart ridiculously quick and easy. Apart from a bunch of bent up metal, I think a lot of the parts are savable and regardless, the parts availability for these little guys is second to none. I've already got a line on a tank and some used case covers, so we'll start there and keep moving.










After a couple hours in the shop, I had the whole thing reduced to a pile of parts and a bunch of ziploc bags. I'll focus first on straightening anything that's bent on the frame from previous abuse, new swingarm bushings and building back up a respectable roller while I evaluate the motor and decide what to do with it.



Mashed up fenders. Should buff out  ::)



I hear curved shocks are the new thing.



And last but not least, a photo of what this tired old machine would have looked like before the abuse. This probably won't end up being a nut & bolt restoration as I plan to bring this thing camping and actually enjoy it. It definitely needs some straightening up, a handful of new parts and some paint, but we'll bring it back to life.






"He broke the mirrors off his Cadillac, 'cause he doesn't like it looking like he looks back."

74 CB360 - Luna - http://www.dotheton.com/forum/index.php?topic=63294.0 - Sold
82 GS550L - Tracker-ish - http://www.dotheton.com/forum/index.php?topic=67229.0 - Sold
74 XL350 - The Turd - http://www.dotheton.com/forum/index.php?topic=70252.0 - Sold
Suzuki FA50 "No-Ped" - http://www.dotheton.com/forum/index.php?topic=71189.0
73 Suzuki RV125 -http://www.dotheton.com/forum/index.php?topic=73875.0
'97 BMW F650st - http://www.dotheton.com/forum/index.php?topic=75732.0

Offline canyoncarver

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Man, that's crusty.... 
--

YZF750/1000R The Fly
KZ 750 Twin
ZRX 1100
KZ400 The Rabbit
KLR650, 65 Norton, my never finished shovelhead chopper, an 86' FXR, and an F9 Bighorn
more YZF750R's, more KZ's, a Zephyr750...and the ever unfinished 75' CB550 cafe.
--

Offline 1fasgsxr

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I think that rear fender is salvageable... ;D
http://www.dotheton.com/forum/index.php?topic=41083.0

Life is a journey from the maternity ward to the crematorium....

Offline Maritime

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Yep. too bad the parts lot I found was sold. would have been useful. I'll keep an eye out as it looks like stuff is cheaper here when it can be found.
The GL Rebirth: http://www.dotheton.com/forum/index.php?topic=68337.0
CX500 Low budget Bobber : http://www.dotheton.com/forum/index.php?topic=43617.0
"Beer makes you feel the way you ought to feel without beer" -Henry Lawson
"Beer is proof that God loves us and wants us to be happy." - Thomas Jefferson

Offline Hurco550

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This is stupid. Im in.
"If you just picked up a drug habbit instead of a kawasaki triple at least you could get high while you waste money"
~ bradj
1988 tw200, the swamp donkey: http://www.dotheton.com/forum/index.php?topic=75455.0
2006 Suzuki DR650 Adventure monowheel trailer build: http://www.dotheton.com/forum/index.php?topic=75033.0
1976 BMW R90/6 farkilitious: http://www.dotheton.com/forum/index.php?topic=74349.msg882477#msg882477
1975 RD350 Road Racer: http://www.dotheton.com/forum/index.php?topic=70652.msg833688#msg833688
1976 GT250 Rebuild: http://www.dotheton.com/forum/index.php?topic=64973.new#new
Full Custom Pit Bike: http://www.dotheton.com/forum/index.php?topic=66954.new#new
1971 Yamaha 90cc twin HS1: http://www.dotheton.com/forum/index.php?topic=70498.0
"much ingenuity with a little money is more profitable and amusing than much money without ingenuity" - Arnold Bennet

Offline Brodie

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I have a soft spot for the Z50 range.

I am not 100% sure on American models but that looks to be a Z50A K6.

If you do go to a larger engine I would recommend 140cc being the largest to use without getting an extended swing arm and 10" rims.

Can't wait to see what you do with it.
I'm not sure, but don't ask Brodie.

Way to many build and half done projects to list here.
Sr250, Gs750, Z50A, XV1100, A10, Z160A.

Offline irk miller

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I am not 100% sure on American models but that looks to be a Z50A K6.
It's a Z50A in the US, too.  But it's a 78, so K9.  You southern hemisphere people might read that as a 6, though.

Offline advCo

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According to the service manual, K5 is the last designation on Z50A models. I've seen the late 70s models referred to as K6 on parts website's though, so not 100% clear on that.

I cracked into the motor last night. Some buggered up threads on the flywheel but I was able to get my puller on there regardless. The top end looks great and should look better once I get rid of all the carbon deposits. Piston and bore were clean as a whistle.





Fun fact, the oil filter nut tool for Honda twins is the same tool needed to remove the nut holding the clutch assembly in place.



Here's the clutch side where the case was destroyed and some dirt got in with the primary drive gears and clutch assembly removed. The clutch assembly is toast and will certainly need to be replaced.



I tilted it towards me and sprayed a whole can of brake cleaner on there and gave it a quick toothbrush scrub and wipe down before I split the cases.  Not bad at all.



Once everything was uninstalled and relatively cleaned up, I heated up the case seam all the way around with a propane torch to help soften the gasket and release the case halves. You can gently pull the top end studs away from one another and tap the crank end with a rubber mallet to free the right half of the case from the left. Amazingly the bearings spin freely and don't have any grit in them at all.

The crank and transmission gears are all moving as they should. I was really expecting this bottom end to be trashed, but I think it will live to see another day! I need to check the crank for runout.

I think a good run through the parts washer, and some new seals and gaskets and I'm going to try my luck running this bottom end.


"He broke the mirrors off his Cadillac, 'cause he doesn't like it looking like he looks back."

74 CB360 - Luna - http://www.dotheton.com/forum/index.php?topic=63294.0 - Sold
82 GS550L - Tracker-ish - http://www.dotheton.com/forum/index.php?topic=67229.0 - Sold
74 XL350 - The Turd - http://www.dotheton.com/forum/index.php?topic=70252.0 - Sold
Suzuki FA50 "No-Ped" - http://www.dotheton.com/forum/index.php?topic=71189.0
73 Suzuki RV125 -http://www.dotheton.com/forum/index.php?topic=73875.0
'97 BMW F650st - http://www.dotheton.com/forum/index.php?topic=75732.0

Offline Maritime

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The GL Rebirth: http://www.dotheton.com/forum/index.php?topic=68337.0
CX500 Low budget Bobber : http://www.dotheton.com/forum/index.php?topic=43617.0
"Beer makes you feel the way you ought to feel without beer" -Henry Lawson
"Beer is proof that God loves us and wants us to be happy." - Thomas Jefferson

Offline irk miller

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The Z50A definitely goes to K9.  Your manual may predate the end of production.  Honda always designated that number by year.  What does the VIN tag say?