Having to run the engine wth the choke on is usually a sign of a clogged pilot jet. Unfortunately, you can't remove the pilot on the 50 carb. You have to soak it in a good carb cleaner, usually overnight, and use compressed air to blow out the internal passages.



Battery info from the Yuasa website:



Honda - Z50A (K1) 1969-1970 50cc

Battery Family: Conventional

Battery Type: 6N2A-2C-1

6N2A-2C-1 replaces B60-6

available at Honda dealers only

Voltage: 6Capacity: 2

Dimensions: 2 3/4" x 1 7/8" x 4 3/16"Weight: 1.0 lbs.

Metric Dimensions: 70mm x 47mm x 106mm

Metric Weight: .4 kgPolarity:

Acid Volume: 3.4Amps: 0.2

 

Looks like dirtbkr188 types faster than I do.



BTW, I think he's exactly correct. I have found his tech help to be very useful in the past ! He came up with the same diagnosis while I was typing mine !



I'm gonna post this anyway. Maybe reading this from two perspectives will be of use.



It sounds like you have a clogged pilot jet. When the pilot (low speed) jet or the passageways ahead of it aren't clear, the engine will only run with the choke on.



1) Remove the carburetor from the bike. 2) Remove the carb adjustment screw. 3) Remove the bowl from the carb body. 4) On my K2 carb I was able to do this, maybe the one on your '74 (K5) isn't removable. If you can, remove the the pilot jet and ensure it's clean. 5) Spray carb cleaner into the passageways where you removed the jet. If the pilot jet isn't removable on your carb, simply spray cleaner into the jet. 6) Look at the back of the carb (where it attaches to the air filter) and you should see a small opening or two - spray carb cleaner into those openings as well. 7) When the passageways are clear, the spray will come out of the passageways at another part of the carb. 8 ) Use compressed air to "blow out" the jet and the passageways before reassembly. 9) Put the adjustment screw back in and set it to approx. 1 1/4 to 1 1/2 turns counterclockwise from fully seated position.



Many times the jet will be clear, but the passageways in the body of the carb will still be clogged. Unfortunately, it's not unusual to have to clean a carb several times. Be patient. Repeat as necessary and you'll soon solve the problem.



In a worst case scenario, you may need to remove all rubber (o-rings, seals, etc.) from the carb - and soak it in a carb cleaning solution for a while - then rinse it - blow it out with compressed air - and reassemble.



Regarding the '69 (known as a K1 model): YES it came from the factory with a 6 volt battery. It is the only model of Z50A that was this way. The year before it (K0) had no lights or battery. The year after it (K2) had lights but used a magneto-based lighting coil - without a battery.



Hope this helps !



Resto

 

^^^^^ Man you guys are good.

tmas

 

battery like this...

don't forget the square orage part... rectifier!

 

Just a question to gain further knowledge, what's a rectifier and what's it do?

(Hehe. Reminds me of "Who is your daddy, and what does he do?")

 

Wow, a one pound battery? thats pretty small.



First id just like to get to know you....

Im detective John Kimball,

Im a cop you idiot!

 

Just a question to gain further knowledge, what's a rectifier and what's it do?

A rectifier "converts" AC voltage to DC voltage. The AC voltage generated by the stator can't be used to charge the battery unless it is converted to DC. That's why there is no such animal on a bike w/out a battery.



For what its worth, modern units are basically an arrangement of silicon diodes. Based on the shape of the ones that are used on the old z50s, though, my bet is that they are selenium rectifiers which haven't been used for quite a while now.



/dayj1

 

dayj1, Nice explanation about the function of rectifiers. You're right about the old ones being called selenium rectifiers.



I may have missed this from your earlier post about the Retro bike in your avatar.....but are you using a 12v system on that one ? If I'm not mistaken, your headlight looked like some type of HID unit or maybe a type of halogen ? Are you using a battery or does your lighting coil supply the juice ?



Looking forward to more pics as you progress with that build.



Resto

 

dayj1, electrical question....



on my Z50A-K1 1969 i got a battery with selenium rectifier.

the stator generate 6 volts... i would like to know what amout of watts that i can put on?

on tail light i will have two light. no switch brake. no flasher. and for front head light i'll had hi & low beam + small light on top head light.



difference between 12 volts & 6 volts is the bulb light? or wire are bigger or smaller? the stator is different i understand that... but there's other difference?

because when i bought tail light (twin) it's 12 volts light inside... if i change for 6 volts i'll be ok?



how many watts i could put on the system without burn it?

thanks!

 

are you using a 12v system on that one ? If I'm not mistaken, your headlight looked like some type of HID unit or maybe a type of halogen ? Are you using a battery or does your lighting coil supply the juice ?

I'm using a 6V points motor from a K2. The headlight is a NOS Unity spotlight from the 1950s that houses a 4 1/2 inch sealed beam (PAR-36 type bulb). Since it is a spotlight, the original bulb only has a beam spread of about 5 degrees (which is too narrow for a useable headlight). There are plenty of PAR-36 bulbs out there of different wattages, voltages, and beam types and I've still got to order one of the proper type. Lastly, I'm using a lighting coil only (no battery).

on my Z50A-K1 1969 i got a battery with selenium rectifier.

the stator generate 6 volts... i would like to know what amout of watts that i can put on?

I don't know the EXACT answer to your question about the wattage of the lighting coil. The best place to get that information would be from Honda, but I've never seen it in print anywhere. One could also make a safe estimate of the wattage based on the fuse size, but Honda only fused the battery charging circuit and not the lights! There are some knowledgeable folks on this forum, so perhaps someone can post the answer.



With that being said, I took a quick look at the k1 wiring diagram. It looks like the maximum wattage would be when the hi-beam, indicator, tail light, and brake light are all on. That would be 15 + 1.5 + 5.3 + 17 = 38.8 watts (at 6 Volts, that is about 6.4 amps).



Another way of getting to the same number is just by the wire guage. My stator appears to be 22 gauge copper wire which has an ampacity of 7 amps (42 Watts at 6 Volts). 42 Watts would be the theoretical maximum, so back off the 7 amps by 10 percent and you get 6.3 amps which is in agreement with the paragraph above.



I thought I'd post the above theory just for some background (and so you guys wouldn't say I was making it up ) The bottom line is that the lighting coil is most likely a 40 watt unit.

or wire are bigger or smaller?

You won't need to change any of your wiring to a larger gauge.

i bought tail light (twin) it's 12 volts light inside... if i change for 6 volts i'll be ok?

Change your light bulbs to be 6v units and you'll be good to go. Just make sure that the wattage for your headlight, tailight, and hi-beam indicator bulb all add up to less than 40 Watts.



/dayj1

 

thanks for the info dayj1!