Planet Minis

Heretic

Hey guys, I've recently started prepping my NS50 to be a race/track bike at the local kart rack. I also have a 1972 Z50 Minitrail in the garage, and I want to make it a road racer too. It's currently Mostly original and very tired, but I was thinking about freshing the motor up (Probably with one of those cheap eBay motors, like the 6hp - 86cc 4 speed semi auto)

I want to keep it Semi auto since it's for my little guy to learn to road race on. I can always dial the throttle stop back and slow him down.

So the motor is the easy part. Any help with brake parts, especially upgrade parts, or aftermarket brakeshoes. And what about grippy road rubber in the 8" size? Suspenison pieces? Fork Springs, rear shocks, etc?

Any help, advice, pictures, anything would be great.

Thanks,
Joe

s_10onbagz

It is tough to road race with no damping at all. If you really want to run stock suspension setup, just get some dampened rear shocks, and some not so aggressive +1" front springs. Heidenau tires are what most of the guys run, the past couple sets of wheels I've had I just ran Cheng Shin tires. I think Vee Rubber might sell 8" slicks. 10" wheels are really the way to go.

arlindsay1992

I have a 1984 Z50R I race at kart tracks. It's a lot of fun. I would first off suggest staying with a Honda based motor. The Chinese motors have transmission issues and you will need to redo the entire electrical system because they are 12v motors. TB makes 88 kits for your bike. They also make HD auto clutches and sell the 4 speed tranny that AHP makes.

For suspension, the bike will handle a lot better with a longer swingarm. The XR75 swingarms can be easily modified to fit. I have modified a few for other people for $25 + shipping, they provide the core. There are usually a few for sale on eBay. For shocks, any 330-345mm shocks will work. Kitaco has a wide selection of nice shocks in various sizes, but CT70 shocks will work just fine for a bit less. Usually the dampening is gone. Up front, the stock forks are scary on a track. They wobble at speed, during turns, and when braking. Any oil dampened fork will work. Getting the wide Z wheel to fit is difficult. I used a CRF50 front wheel. For the rear, I still have the 8 inch wheel with the KT-903 tires. They are getting hard to find now because they are discontinued. For brakes, there are a few companies that make expensive shoes and such but I have always bought the cheapest I can find. I found that simply making sure that everything is as clean as possible and well adjusted makes the cheap stuff work very well. I have no problems on a track using my cheap shoes. I'll have some pictures tomorrow of my bike and some of the technical bits.

Heretic

Do the newer XR/CRF 50 forks have dampening? I would assume they are an oil filed fork?

Maybe a update to CRF 50 wheels, forks/tripples? Would need to change the rear swingarm for something else to use the CRF 50 rear wheel though. I would probably just run the stock 8" rear wheel with the 10" front. Get some decent shocks for the rear.

I'm getting some good ideas for sure.

simmersm

xr/crf50 forks are pretty much identical to the Z50 forks.. the diference is that the Z forks are wider

Heretic

So just springs, no dampening?

Maybe it's not that bad, lots of kiddies at our track run on XR/CRF 50's with just road rubber.

I should really trade the Z50 away for something different, it would be kind of a shame to wreck a vintage one. They went from being something you bought at a garage sale for $30, to being quite collectible. It's not mint, but you know someone may want it to restore. Been in our family for decades though. I rode it when I was in my early teens, then my brother as a little kid.

simmersm

nope.. no dampening... just springs, bushings and some grease..

arlindsay1992

The stock forks are scary on a track like I said in my last post. You can spend some money and get them to be a bit better but they are never very good. You can get +1 legs and HD springs, and Delrin bushings to get some good performance but you are then at about the price of used SP-5's or CRF70 forks.

Use the Z50. The softtails are never going to be very collectible unless they are absolutely perfect, other than that, they are just going to be "good learner bikes" when you try to sell them. A CRF50 might be easier in the long run but everybody has a CRF50. I like to have the only Z50 out on the track.

Here is mine. You can see the XR75 swingarm and CT70 shocks. I can mod the swingarm for you if you provide a core. Up front I used SP-5 forks. I did some work to them myself. I shortened them so they have 1 inch less travel and 1 inch less length, but still have the BBR dampening rods. Combined with 15 wt oil these are perfect for the track. The rear end is a little stiff for my liking, I'm trying to find springs more suited for my 145 pounds. Let me know if you have any more questions.