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

[Amber Lamps]

Originally Posted by askmrjesus

That's a good question. Most people mistake brake cleaner for something that is meant for cleaning the entire brake system, when in reality, it's really just for pads and rotors.

Kaneman, if the spray cleaner isn't getting the job done, you might want to try a dunk tank (carb cleaner in a one gallon gan, with a basket for setting the carb in) and soaking it overnight.

Paul also had good advice about checking the boot for holes or rips. An air leak would definitely cause the symptoms you're describing.

JC

I had a good question!!!!!

[Rangerscott]

Blown-up diagrams

http://dratv.com/nez50pabydi.html



I use those cheap walmart brake cleaner and carb cleaner (blue cans). The carb cleaners does a better job taking stuff off, but leaves a little residue behind. I let the carb cleaner dry then hose it again with brake cleaner to get the rest off.

[Kaneman]

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 my original carb 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?


________
Honda cm400 history

[Rangerscott]

Thats the vent tube. Youre main jet is screwed into the bigger tube behind it.

[Amber Lamps]

Originally Posted by Rangerscott

Thats the vent tube. Youre main jet is screwed into the bigger tube behind it.

Ha I thought it was the pilot jet or something! I think the main question was if it was supposed to flow freely? Apparently he has something stuck in his.

FWIW I agree with you that if it ran for a minute and then quit it's almost certain to be something stuck in the fuel system somewhere. It even makes more sense when you consider that the original owner couldn't get it to start but it fired up for you... probably just long enough to lodge whatever back into wherever.

[was92v]

Originally Posted by Kaneman

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?

Umm, I believe that would be the pilot jet, which is the problem. On an engine/carb that small, the jet orifice is so small that a thin needle might pass through if it were clean. Soak the the carb body in a carb cleaner vat (Barryman gallon can) for a day or three and use compressed air to blow it out. The pilot air screw passage should intersect with the passage that the brass tube is in, within the carb body and will exit through a tiny hole in the floor or side of the carb bore on the engine side of the throttle valve. There will be a pilot air inlet in the bottom half of the air inlet velocity bell that feeds air to the pilot circuit that also needs to be blown out with compressed air. Any or all of these could be clogged, but the pilot fuel jet is most likely the bad guy.

If you spray a little bit of carb cleaner into the Pilot air screw hole and blow air in the that passage it should exit out of the brass thing you are pointing at, the outlet hole engine side and out of the air inlet on the air box side.
If stuff doesn't spray out of all of them you have a clog in the one (or more) that doesn't puke carb cleaner.
Does any of this make sense?
The above is a general shot at this, but I have a 70cc version of that engine laying around somewhere with the carb on it. I may take it apart and see what all is in there.

[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.


________
Subaru Ff-1 Star

[Rider]

Running rich but what I find suspicious is that only half of the plug is black. It's not blowing any smoke when it runs right? Did you ever check your valve height? Run a compression check also.

[Kaneman]

Originally Posted by Rider

Running rich but what I find suspicious is that only half of the plug is black. It's not blowing any smoke when it runs right? Did you ever check your valve height? Run a compression check also.

It blew some smoke yesterday when I first started it before I rode it but then it seemed to be clean. I held my hand behind the exhaust for a bit and came up clean.

You're right, only half the plug is black...I didn't notice that.

I didn't check valve height or run the compression check. I'm wondering if I need special tools for that? Going to look it up in the shop manual...
________
Zoloft Class Action

[Rider]

One other thought is to double check that the plug you are running is rated for the correct operating temp. A plug that runs too cold will cause a rich condition. You may need to run a hotter plug.