[Kaneman]

Hey guys, I'm new here, wanted to get some advice from the experts.



I picked up this 84 Z50R in a trade with a guy. Bike seems to be in decent shape, he told me it wasn't running and he hadn't ridden it in 2 years or so. He had like 5 50's in his shop.



Anyway, so I got it, turned the gas on and cranked it for a bit....low and behold I got it to fire up. Rode it up and down the street. It was running but not very well, didn't have power under full throttle and had poor throttle response.



So, shop manual in hand I took the following steps:



1) Changed the oil only to find that the oil in it was brand new.

2) Bought a new air filter

3) Drained all the old gas and filled it with fresh 87

4) Removed the carb, sprayed and soaked with Carb cleaner



After all that it ran more poorly, as seen in this video. This is the first time it was started today and fired right up after a couple of kicks on choke:





So I pulled the spark plug, which appears to be getting good spark. It looked pretty good, but just in case I replaced it with a new one.

Here's the original:

That didn't make any difference. Right now the jet needle is on the factory default second notch from the top. However I have tried 1 through 4 without any varied result:

This video was taken after the spark plug change:





Here are some more pics of the carb:

So, any suggestions on what to try next? This is really my first shot at anything besides basic maintenance. I should have all the tools I need to work on this lil' 50 motor and I have the shop manual. Any advice or suggestions are greatly appreciated, I know there's some real experienced folks here. I've got all day so if you need some pics or more video for a good diagnosis let me know.

 

[ducatilover]

check the timing and points. When in doubt change the points and condenser. Some guys will file the points down until they are even. I would put the needle clip in the middle.

 

[dirttrackin280h]

Did you blow all the passages in the carb. with compressed air? Are you sure all the passages are clear?

As ducatilover said, check the timing and points. I would just purchase a new set of points just for the heck of it, they are cheap (under $10).

Bad points can cause the bike to run all sorts of different ways. One of my bikes did the same thing, it wouldn't open up, just bog....until I replaced the points.

Argghh points, hate 'em.

 

[Branyers]

Looks like there is some gunk in that carb. I would remove the pilot and main jets and look through them in the light to make sure they are not clogged. Sometimes to get it all out you need to use a jet cleaner (not a needle because it may widen the hole). Soaking the entire carb body in cleaner may not be enough. New points and condenser if the above produces no change. Also try moving that needle clip down one or two positions.



Good pictures btw.

 

[Kaneman]

Thanks guys, I'm pretty new at all this so I'm learning as I go along.



I just picked up some seafoam and am going to try to clean the carb again with that. I don't have an air compressor so I'm not exactly sure how to make sure the jets are clean...I haven't tried taking them out yet either so I'll go see if I can do that without breaking them!



Forgive my newbness...but what are points?

 

[Kaneman]

Did some research on the points/condensor...looks like I'll need a flywheel puller to do that job? Crud.



I took the plug out and kicked the motor with it touching the exhaust pipe...as far as I can tell its getting good sparkage.

 

[Branyers]

Looks like the '84 Z50 pilot jet is pressed in, meaning it's not removable. But you still might be able to clean it with the appropriate sized jet cleaner.



The main jet can probably be removed with a screwdriver, but be careful not to be too forceful or you may damage the brass. Once the main jet is removed, the needle jet is just above it. Pop that out and make sure it is not clogged either. Hold them up to the light. You should be able to see through the holes.



Points and condenser are underneath the left engine cover, located behind the flywheel. They are visible through the holes in the flywheel.



Here's a couple of diagrams you may find useful:



OEM motorcycle and ATV parts from Honda, Yamaha & Polaris – Cycle Parts Warehouse



Alternator



Carb

 

[Kaneman]

Thanks guys...



There's no way that its the carb, that puppy is clean. I sprayed all the jets out with carb cleaner and it came out the other side in a fine mist. Reassembled and is still running like crap.



I can keep the motor running if I hold it to full throttle but anything less than that and it putters to a stop.

 

[Kaneman]

Points and condensor are around $45 at my local Honda shop, (Honda/Kawasaki West, Fort Worth Tx) and are not in stock so I'd have to order them.



Dang it.

 

[dirttrackin280h]

www . dratv . com has the points and condenser for $ 11.99. IN STOCK

 

[Kaneman]

www . dratv . com has the points and condenser for $ 11.99. IN STOCK

Awesome! Thank you!

 

[tmas]

If you go to Honda50.com they have a 1979 - 1987 on line manual. Check link below.

tmas



Honda50.com Parts Lists

 

[88ccmotoX]

Thanks guys...



There's no way that its the carb, that puppy is clean. I sprayed all the jets out with carb cleaner and it came out the other side in a fine mist. Reassembled and is still running like crap.



I can keep the motor running if I hold it to full throttle but anything less than that and it putters to a stop.

It may spray all over but I suggest running a small wire into the pilot and main passages to make sure they are open.

My 2 cents,

 

[Kaneman]

It may spray all over but I suggest running a small wire into the pilot and main passages to make sure they are open.

My 2 cents,

Well it just didn't make sense to me that after I started messing with the carb the bike pretty much stopped running. On the first night I had it I was able to get it started and ride up and down the street...so I suspect it was still the carb.



I got a couple of other motors and a spare Z50 parts bike. I stripped the carb off that bike which was different from the one on my bike, took it apart, cleaned it out and put it on. I tinkered for a while and got it running....and actually got it to rev....hmm....



Click it into gear and I'm gone, up and down the road, no backfires...so its gotta be the carb. Now, I looked at the schematic of the carb I took off and it exact matches the Z50R.....so I'm wondering why this other carb works better.



Anyway, I do have another question. In this pic of the carb that was on the bike when it was not running you can see the brass tube I'm pointing at which I assumed was a jet. I tried to run a very very thin copper wire in there and it won't go more than 3cm down. Is this passage supposed to be open or do I have a major clog?

Here are the two carbs side by side. The one in my hand is the non-running carb...which I think may actually be the correct carb.

 

[arlindsay1992]

You can get a CRF50 carb for $10-$20 in the classifieds. It will bolt up and run for another 30 years. Just make sure you get one off of a 2005 or older so you have the adjustable needle and air screw.



As for which carb is correct, the 1984 Z50R has a very similar carb to the one in your hand. The one on the bike is off of an older Z50. Either a hardtail or early softtail.

 

[mexicanyella]

Early softtail. Hardtail carb was more square-looking in the bowl; had different "guillotine"-style choke instead of butterfly.



I'd say if the bike runs well with the second carb, your work there is done. Take the shiny carb apart at your leisure and figure out where the blockage is. I don't have a Z50R carb here to look at, but from the vid and posts it sure sounds to me like there's a blockage in there somewhere and the bike's running lean enough to have poor throttle response and make little popping backfires occasionally.



As mentioned above, dirty, pitted or incorrectly gapped points can sometimes do this too, although when they do you'll usually get a dry, sooty black spark plug from the weak spark/incomplete combustion. These symptoms, when they come from lean mixture, instead should give you a real clean whitish plug from overheating the plug.



In any case it sounds like your problem isn't points this time. But don't be afraid of the points. Get yourself a flywheel puller and swing by a NAPA store and get yourself a points file, and a good feeler gauge. And a can of electronics cleaner. File 'em flat if needed, clean them with the spray cleaner, set gap to .012"-.016". (You have to set the gap with the flywheel installed, because the points cam is part of the flywheel, but it's easier to file them with the flywheel off).



More than 90% of the time that's all you need to know about older Z50 ignition systems. It's an easy process and diagnosis gets easy once you've done it a few times.



Cool bike; high-five yourself a little bit.

 

[Kaneman]

Great advice guys, thanks.



I got it to run for about 30 minutes up and down the street until the cops told me to keep it off the road. At that point I was gettin pretty hot (103 outside) so I put it up. I had noticed that the performance was falling off a bit toward the end.



This morning I can't get her to start for my life! Pulled the plug and this is what it looks like....this is a brand new plug minus 30 minutes of use...what do you think? Also, i've got a buddy coming over with some carb soak so I'm going to put both those carbs in there.

 

[mexicanyella]

I'd replace, or file and gap, the points, just to be sure. That's a dirty plug; either it's got a weak spark, or is burning oil, or is running rich. You seem to feel it was running okay for most of the ride, so I'm a little less inclined to say it's running rich, but was there any exhaust smoke? Black = rich, blue or blue/white = oil burning. My old hardtail Z50 engine is worn enough that it blows a little blue smoke after it's idled for a few minutes (probably worn valve guides allowing oil to come down the valve stems under high-vacuum conditions--idling--but it uses very little oil and the plug stays pretty clean and rarely fouls...unless it's time for a points setting operation.



So by doing the points and getting a known strong spark reestablished, you're eliminating a large variable.



It's worth it, while at NAPA or wherever buying your points file, to get a jet cleaner or torch tip cleaner, which is a little folding thing with a bunch of different stiff serrated wires hinged into it. Handy for cleaning deposits and crud out of jets. It doesn't take much crud to have an impact on fuel mixture. Sometimes soaking doesn't do it; it dissolves the varnish but sometimes particles of grit or dirt or fuel tank rust still remain lodged in there.



Also if blowing air through passages and jets with a compressor and nozzle, be aware that it's fairly easy to launch jets into low earth orbit.

 

[hall]

Great question regarding the brass tube. Is that the idle jet/idle circuit? Mine doesn't appear to be open either. I've got carb issues on my 2003 crf50...



[quote name='Kaneman']





Anyway, I do have another question. In this pic of the carb that was on the bike when it was not running you can see the brass tube I'm pointing at which I assumed was a jet. I tried to run a very very thin copper wire in there and it won't go more than 3cm down. Is this passage supposed to be open or do I have a major clog?

 

[ridered_17]

check the valves with a fueler gauge. the gap should be .002 inches.







ridered_17