Planet Minis

alpinaclone

I just picked up a 1979 z50, it is the most beat down motorcycle that I have ever purchased but that is beside the point.

It does not run due to weak spark, but that should be easy to cure. The part that I am having issue with is that the PO swears that the bike is a 4 speed. Being a non runner, it is hard to tell by just shifting through the gears with it sitting in the garage. Given the state of the bike I would not be surprised if the original bottom end had been swapped out for a 4 speed ct70 unit. The engine number is AB02E-5005870. If someone could provide any insight as to what I may have I would greatly appreciate it.

Thanks, Matt

FastMC

Going by that eng number, it's the original engine.

alpinaclone

Ok, 3 speed then. Thanks.

alpinaclone

Also, if the ignition system is fooked, would one of those ebay inner rotor kits work ok for a kids playbike? Or would it ruin tractability? The reason I ask is, you can see that some of the windings on the stator are broken. Could they just be re wound?

Sorry for all of the newb questions. I am not used to these points thingies.

cdoublejj

rewinding isn't a walk in the park it's huge pain in the ass and if isn't done precise enough or wrong it's still fooked, weather it has all the same timing marks i'm not sure

mexicanyella

I am in the minority on this board with my feelings regarding points, but for what it's worth, I think people bitch about points too much. Once you understand how points ignitions work, and get a few tuneups under your belt, the good aspect of them is that they're easy to set up and you can, with a few tools, pretty much always get them to work again. You have to file the contacts (or just replace the points) and set the gap periodically, but to put that in perspective, I've been riding the same 1971 Z50A since about 1991 and have been into the ignition on it five or six times. I have not replaced the points or condenser yet.

I've replaced the ignition coil once--with a spare used one off my parts bike--and each time I've done something for no spark/weak spark other than that coil replacement, it's been pull the flywheel, clean up the points with my points file, clean out the shavings from filing them (with a squirt of aerosol electronics cleaner), replace the flywheel, set the gap, ride. I've not been too consistent about dabbing a little bit of lube on the little lube wiper that's in there either, and it's not been a problem.

Adjusting and oiling the drive chain has been more work than fiddling with the ignition by far, looked at over the long term.

Now, to be fair, my bike's had a few periods of sitting mostly idle for a year or two here and there, only being started every couple months or so. so it's not been 18 years of constant use. But some of those ignition sessions were probably the result of sitting idle. I last cleaned/gapped my points back in October or so, and my bike's been in daily use around our farm since, and hasn't missed a beat.

People who run their engines at consistent very high rpm might require more ignition maintenance than me, due to increased wear from more rapid opening/closing of the points themselves. Not sure about that. Most of my riding is between clutch-engagement speed (3500 rpm or so) and 6500-7000 (25-30 mph in high gear). Some people, especially ones who've modded their engines for better breathing, probably spend more time up around 8000-9000 than me.

Anyway, I'd suggest looking for some replacement parts for the stock ignition, which I have found to be a simple, reliable and easy-to-diagnose system. If you decide to go this route, I'll be happy to explain setting the points and checking it out for faults. Let me know. The parts to fix yours are available from CHP, Dr.ATV, Trail Bikes and others, and you could probably find the coils under the flywheel used as well. Watch the Z50 section of the classified ads on this board for someone scrapping their stock ignition after putting on an aftermarket internal rotor system. As far as that goes, I may have some Z50R points system spares too in a week or so. I have a parts trade in the near future and some Z50R stuff might be in the pile.

Putting an aftermarket electronic ignition on your bike will certainly remove the need to ever check points again, and might in theory give you a hotter spark. On the other hand, I don't believe a stock or near-stock bike needs a hotter spark to run well. And if it does pack it in, you can't just stick a couple tools in there and slap it back into shape; you're into replacing sealed components and using a multimeter or whatever. I don't own any electronic ignition bikes, and the one I did have (YZ490) never required any ignition attention. But on my Z50 and my CB450, plus various tractors around here, I've come to appreciate the simple nature of points and I personally like knowing what's happening in there with those electrons and being able to see why it's not happening when something goes wrong.

alpinaclone

Thanks for the advise. My father swears by points, even in his cars, so the idea is familiar even if the practice isn't. The reason that I asked about the inner rotor kit was cost not performance. $30 shipped on ebay is dirt, unless it ruins the bike to put around on. I will prolly try to find a used stator and just get it going as is.

I need to get some pics up to show you guys what a mess this thing is in. I am pretty impressed that this thing was recently a runner.

mexicanyella

I would love to see its "as-found" condition. I like seeing bikes that look really trashed and still work, or at least worked recently. Isn't that what they call "prurient interest?"

I didn't realize the Ebay internal-rotor ignitions were that cheap. I suppose for that price you could buy two or three of them and keep the extras wrapped up as spares in the garage in case a mystery sealed component packs it in, at which point you can just swap parts until it works again.

However you might want to have a look at what kind of shape the stock wiring harness is in. If that's been hacked, that might tip the balance of the decision toward the aftermarket route. If it's still intact, you might want to consider not hacking it and fixing the stock setup.

I've never run an internal-rotor thing (other than the stock rig on my old RM I used to have) and many others here have, but I'm pretty sure with the clutch also being on the crank and the mild nature of the stock Honda tuning it would still work. There's still plenty of inertia in the rotating assembly with that clutch spinning at engine speed, I'd wager.

arlindsay1992

I totally agree with post #6. I have the stock 6v ignition on my 1984 Z50R. It is so easy to use. I replaced them once because the original ones started to transfer metal after 24 years. This bike has a TB 88 RH kit and frequently sees 9000-10000 RPM. I adjust the points twice a riding season just to keep it perfect although I'm sure it would run fine if I didn't. I also like the easy adjustability of the timing whereas the CDI motors are dead set unless you want to start grinding away metal.

Of course, from a standpoint of "I just want to ride it," a person should buy CDI. Admittedly, it took me a while to figure out how to set it up when I was 12 years old. But now, I can set it by eye and not have to touch it again.

alpinaclone

Finally snapped a few pics.






It has some promise I think.

arlindsay1992

I've seen worse, much worse. That bike could easily be cleaned up and running for cheap.

alpinaclone

Oh yeah, it is definitely savable. What surprised me is that it was ridden like this up until about 2 weeks ago. Every bearing and bush is shot, the forks are beat, looks like it was wired by 3 year olds, and the then there is obvious side cover delete mod. For $100 I think I did well. I'm looking forward to digging into it.

mexicanyella

The obvious side cover delete mod. Heh.

"For $100 I think I did well." Yeah, no kidding. Well worth it. I bought a similar one but without wheels, hubs or top end on the engine for $75 awhile back, then out of the blue someone gave me an engineless roller for free, and those two are coming together slowly in my spare time to be my kid's bike.

Thanks to the help of a couple of generous Planet Minis guys, that is.