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Discussion Starter · #1 ·
Hello,

I'm new on the forum but look forward to contributing and learning as I begin to work on a few z50's.

I bought a 79 z50 recently and it wasnt running which is ok because i plan to fix it up and learn then ride a lot. I have the manual and have been reading it several times. I checked for spark against the block and it sparks well. I opened the carb drain and it gets gas. It has compression but ive not a compression tester, yet, i can just tell. Still wouldnt start.

This lead me to believe that perhaps the timing is off after reading posts online and the manual. So i learned how to tweak the timing. As i learned to tweak the timing the 1st try i did it wrong and didnt gap the points appropriately but somehow lucked out and on the 1st kick it ran! This lead me to find other problems (prior owner put in wrong throttle cable which was too short leading to extremely high rpms when choke off).

Anyhow, the bike all the sudden wont start anymore. I went back to the timing, bought a feeler gauge, and reset the timing appropriately (it begins to open at "f" and is open at "t"). I se tthe gap to the manual's spec (.3mm i think it was).

So now, i have spark, i have compression, i have it timed, and i have gas. Short throttle cable aside i should be able to start this thing like it started before. I also know it runs because it ran before by luck of playing with timing.

My question: is there a way to determine if my condenser, points, wiring inside the flywheel, or any of that is bad using a multi-meter or eyeballing it while it runs (if i can get it to run again) or something? I'm about to take the flywheel off and potentially replace the points, condenser and all the innards but perhaps it is not necessary.

The points are flat, clean, and contact well and open well. I did see a somewhat melted wire at the bottom right (see attached pic) but the wire is still strong and it looks like someone wrapped electrical tape on it last time they had it open. Maybe that's shorting something? i think it was the the wire that exists the case via solid black wire to the coil. Auto part Machine Wheel Engine Metal
 

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If you're getting spark, All of that stuff should be fine, however, it has to happen at the correct time. I would make absolute sure that is OK, then look at the carb. I bet the pilot and main jet are clogged. Give the carb a GOOD cleaning and see how it runs.

Good luck!
 

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Check the Kill Switch

Check to see if the kill switch is in the OFF position. I've accidentally switched mine off more than once...and spent a while figuring out why I couldn't get the thing to start. :mad:

If that isn't it, then make sure the carb is sparkling clean (as others have mentioned). Especially the little emulsion tube (if it is similar to my CT70s and CT90), because there are a ton of little holes that like to gum up.
 

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are you sure the throttle cable is too short and that the carb inst just gummed up and holding the slide up?...or better yet that the carb is in need of being cleaned internaly IE ports and jets
 

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exactly..and a rinse and clean up after the bath with carb clean and 120psi

to be honest..no matter how nice the bike is weather im fixing for a friend or just picked it up for myself..the carb is ALWAYS the first thing i go thru cause its useualy in the WORST shape....but rarely do parts in it need replaced
 

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Discussion Starter · #8 ·
thanks all. great support on the forums here nice!

the carb is new (looks brand new with new gasket) but who knows maybe the jets are gummed. i will take it off and clean it. i saw pinesol posted, do people clean carbs in a bath of that or does a local auto parts place carry like a gallon of cleaner i could purchase? any recommendations for carb cleaning solution would be great. we have oriellys auto nearby.

to answer other questions, the throttle cable part number is for an 86+, i read the 79-85 are about an inch longer of cable. also when the bike did run, the throttle did nothing further confirming this high rpm behavior i think. the choke was the only control i had on rpms.

ill follow up once i clean the carb and know what to clean it in, which solution from where?
 

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i should add this..if you do an "undiluted" mix NEVER exceded 6 hours on STEEL parts as it will rip the zinc coating off somewhere between 6-8 hours..sometime after 8-10 steel will surface rust

that said NOTHING gets a carb cleane4r faster and effortlessly.....tho id still follow up with a can of carb clean(personaly i prefer the CRC red can as it leaves less residue behind) and 120psi thru ALL passages

on the cable...if it has the folding bars then the length will matter....but if it has the 80's bmx style bars..then even tho there is a longer cable i seem to remember it only being noticeable at "full lock"...theres a better chance that it was impropperly adjusted and installed
 

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Discussion Starter · #12 ·
bam, carb back on after bath, and 1 kick start! thanks for the tips.

funny, the pinesol took off the gold'ish colored choke color on the choke lever, its silver looking now :)

i did notice the solid gold/brass looking pin that sits on the end of the throttle cable is bent a little and someone must have grabbed it with pliers because its got knicks in it. perhaps that could lead to high rpm's when choke off? ill find out soon with new throttle cable. can "just" that pin be ordered somewhere? i see it in kits but i only need that pin if the every so slightly bent and knicked would cause problems.

still have a super high rpm when choke heads toward off but i will wait until i have the correct throttle cable for this model and see if that changes it. it's another subject for another thread which ill post after i get the new cable if needed (1-2 weeks).

thanks again all!
 

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With the intake and airbox off the carb, look into the engine-side intake of the carb and see if the throttle slide is fully seated. Hold the carb assembly in one hand and blip the throttle with the other hand, and see if the slide is closing all the way down. If not, either the idle screw is too far in, or the cable is too short. From the airbox side, you should see a slight gap where the throttle slide bevel is.
Also make sure the external throttle cable end is fully seated inside that brass tube on top of the carb cap.
 

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Discussion Starter · #14 ·
i read on another forum post somewhere the same test you describe, looking at the slide and how it sets. i did this with the carb on the bike using a mirror and a flash light and choke open and the gap was pretty big (this is why i checked the throttle cable model and discovered it was for an 86+). so i ordered a new cable assuming the 86+ cable is shorter than the 79-85. i hope this is it.. i did the checks with the idle screw completely out to make sure the slide would fall as far as it can.

anyhow, the slide if just dropped into the carb with no cable on it, falls right to the bottom no problem and slides well.

what do you mean buy the brass tube on the carb cap? my carb cap does have an elbow thats black with the wire coming through it, an o-ring, and the cap itself to twish onto the carb. do you mean inside the carb? if so, im not sure what the cable would connect to since it's sort of nicely fit into the slide..
 

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Replace the carb needle. The needle you have is trashed and causing you problems. Make sure that the cable is the problem. Take the cable out of the throttle and check and see if by pulling the cable by hand you can work the carb slide.
 

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Discussion Starter · #16 · (Edited)
yeah the cable moves well. checked that prior too but failed to mention it. where can i get just the needle? seems it would be cheap and i do not need a full kit.

you mentioned a brass fitting in the cap.. i dont have one but i now i think i know what you speak of.. here is some brass fitting i found on ebay for an older z50's carb. maybe it is not needed with my 79 and thats why there isnt one on mine?

http://www.ebay.com/itm/NOS-Honda-Z...or-Needle-Jet-Set-16012-045-670-/360830927171
 

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Discussion Starter · #17 · (Edited)


Soo.... i went to my other future project bike (75 z50) and took its throttle needle. it is shorter than the 79 (or at least whatever carb the prior owner installed on my 79), maybe 1/4 in. if i guess good. Anyhow, its straight so i moved the little stopper nut/spring thing to the top and slapped it onto the 79's carb. i had to screw out the idle pin quite far but it now idles ok with choke off and revs fine when i pull the end of the throttle cable.

the throttle cable is still too short however. if i put it in the grip/handle it will sit revving high so ill definitely replace the cable with the one i ordered for this.

i wanted to let you know that it indeed was the bent damaged pin (see pic) causing my high rpm with choke off by being stuck up i guess??

i wonder if this shorter pin will be ok with my new throttle cable, guess ill find out. id still like to find out where to just order the pin. $35 bucks for a pin seems ridiculous.
 
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