50cc engine troubles, need some help...video inside.

Kaneman · 06-23-2009, 02:26 PM

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. (For those of you that remember Shugga from SBN and Stuntlife.com, that's who I got it from)

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.
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Rsv1000R · 06-23-2009, 02:30 PM

Get the jets out, and make sure they're clear.
One's in that tube, but there should be a smaller diameter one for idle mixture.

You should also be able to look the part number of the carb up online and find a diagram for it.

Kaneman · 06-23-2009, 02:32 PM

Quote:

Originally Posted by Rsv1000R

Get the jets out, and make sure they're clear.
One's in that tube, but there should be a smaller diameter one for idle mixture.

You should also be able to look the part number of the carb up online and find a diagram for it.

I've got a shop manual that has detailed diagrams. Let me break it down and get a picture of everything and see if maybe I'm missing a piece...

Also, should I maybe run some fishing string through there or something?
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wildchild · 06-23-2009, 02:37 PM

sounds like you may have displaced a piece of gunk while spraying the carb and it is now lodged somewhere. Just a guess of course but i would clean the carb out entirely. soak it for a while them reassemble.

Rider · 06-23-2009, 02:39 PM

Run some seafoam through it just be sure the carb is clean. It certainly looks like a carb/fuel issue. You're not blowing smoke and the plug looks good so you aren't running rich. Have you checked valve height to make sure the valves are opening enough?

Rsv1000R · 06-23-2009, 02:39 PM

Quote:

Originally Posted by Kaneman

I've got a shop manual that has detailed diagrams. Let me break it down and get a picture of everything and see if maybe I'm missing a piece...

Also, should I maybe run some fishing string through there or something?

Once you have it out, you can look through it to see if it's gunked up, if it is soak it, and then spray it out.

While you're not suppose to put anything in it, I've pushed thin wire through them to get some liquid flowing. Just try not to scratch the brass as that will change the flow.

pauldun170 · 06-23-2009, 02:43 PM

carb boot\seal?

BobTheBiker · 06-23-2009, 02:48 PM

very simple. you have a plugged jet somewhere in the system, remove and inspect every jet you can, also check float height and verify its correct.

a valve inspection/adjustment wouldnt hurt either.

Kaneman · 06-23-2009, 02:55 PM

Quote:

Originally Posted by Rider

Run some seafoam through it just be sure the carb is clean. It certainly looks like a carb/fuel issue. You're not blowing smoke and the plug looks good so you aren't running rich. Have you checked valve height to make sure the valves are opening enough?

This is the first time I've heard of seafoam, I looked it up and people rave about it so I'll try to find some locally.

I have no idea about valve height so if I get the jets clean again and it still doesn't work I'll try that.

The float valve was something else I was wondering if I installed correctly. I fit it into the slot of the float and gently placed it into the corresponding hole on the carb when putting it back into place....like so....

It goes into this hole, but when installed remains in the slot in the float...

And here are all my parts...

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Kaneman · 06-23-2009, 03:04 PM

Well I can blow through all the jets pretty freely, don't know if that means anything or not.

I'm going to try and go find some of that seafoam, I'll be back.
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06-23-2009, 02:26 PM	#1
Kaneman AMA Supersport Join Date: Nov 2008 Location: Odessa, TX Moto: 2000 Honda CBR1100XX Blackbird Posts: 4,931	50cc engine troubles, need some help...video inside. 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. (For those of you that remember Shugga from SBN and Stuntlife.com, that's who I got it from) 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. ________ Anal Plug Last edited by Kaneman; 05-09-2011 at 08:07 PM..

06-23-2009, 03:04 PM	#10
Kaneman AMA Supersport Join Date: Nov 2008 Location: Odessa, TX Moto: 2000 Honda CBR1100XX Blackbird Posts: 4,931	Well I can blow through all the jets pretty freely, don't know if that means anything or not. I'm going to try and go find some of that seafoam, I'll be back. ________ Volcano Vaporizer Last edited by Kaneman; 05-09-2011 at 08:07 PM..

06-23-2009, 02:30 PM	#2
Rsv1000R WERA White Plate Join Date: Nov 2008 Posts: 1,059	Get the jets out, and make sure they're clear. One's in that tube, but there should be a smaller diameter one for idle mixture. You should also be able to look the part number of the carb up online and find a diagram for it.

06-23-2009, 02:37 PM	#4
wildchild cruiser Join Date: Nov 2008 Location: on the run Moto: '09 HD superglide, 16 Yamaha FZ 09 Posts: 2,749	sounds like you may have displaced a piece of gunk while spraying the carb and it is now lodged somewhere. Just a guess of course but i would clean the carb out entirely. soak it for a while them reassemble.

06-23-2009, 02:39 PM	#5
Rider Moto GP Star Join Date: Feb 2008 Posts: 12,156	Run some seafoam through it just be sure the carb is clean. It certainly looks like a carb/fuel issue. You're not blowing smoke and the plug looks good so you aren't running rich. Have you checked valve height to make sure the valves are opening enough?

06-23-2009, 02:48 PM	#8
BobTheBiker too much time on my hands Join Date: Jul 2008 Location: the northern district of god damn Moto: 01 ZX6R, looking for more now. Posts: 1,802	very simple. you have a plugged jet somewhere in the system, remove and inspect every jet you can, also check float height and verify its correct. a valve inspection/adjustment wouldnt hurt either.