Leaking oil & possible autochoke problem

[superdan54]

Hi,

Well I plan on de-winterizing my zx50 this weekend. But first I wanted to attempt to fix some nagging problems that seemed to worsen before I garaged it last November.

The major problem is that the thing just has a terrible time starting sometimes, especially after I drive it, park it for a few minutes, then attempt to start it again. Originally I had this problem and fixed it just by changing out the spark plug, but that didn't seem to be the problem this time around. I suspect that it's a problem with the autochoke...perhaps maybe it's not adjusting the fuel intake properly so that when the engine has heated up it lets in too much fuel and floods it?

I've also noticed some oil leakage spots, but I'm thinking it may be from the hose that lets out excess fuel/oil. So I'm hoping the two problems are related. That said, the autochoke is fairly new as I replaced the whole carb system when I purchased it. I'm not really mechanic-savvy, so any other opinions on what it could be would be welcome! Thanks!

[zombie]

For starters I found the "O" ring in the oil tank level sender goes bad. I've replaced it 2-3 times in four years. The oil drips onto the carb so it LOOKS like the carb dripping. The auto choke is a joke in my opinion. With all the plastics off (you have to remove them to fix the oil leak anyway) use a multi meter to test for voltage across the choke leads(while running). If good then pull the choke out, and inspect the "o" ring on it. Leave the choke OFF the scoot for about 10 minutes. Use a sharpie marker and mark the needle at the TOP of the shaft where it enters the body of the choke. Apply 12 volts to the leads (off the battery) and note if the needle moves in a minute or so. It should move downward.
This should get you in the right direction for repairing it. Post back with your findings, and if you need more help.

[superdan54]

OK thanks for the tips...I think that's a much better way to test the autochoke than what the service manual said.

I've just gotten all the externals taken off, and I noticed that the oil/gas is actually leaking back into the air intake/filter and then dripping out the backside of the casing there. Anything in particular that would cause it to do that?

[zombie]

Your reed valves. They are stainless steel, and will take a "set" or bend. You can turn them over for a short term fix but they will soon break off. You can order a new set from www.stadiumyamaha.com/ or get a .030 carbon fiber "blank" (I use Boysen), and cut a new set. The reason is they are flaps that control the vacuum inside the engine case, and will bend after some time. When your piston is on the downward stroke it creates a back flow that is getting past the reeds, and out the carb.
Your scoot will run MUCH better when you replace them, and even better than new if you opt for the carbon fiber. The C.F. blank can be bought at any good cycle shop. They can even cut them for you ( for a few quid)
Keep us informed...
ps... You can buy a set of Malossi reeds from http://www.spi-parts.com/ 10% off if you mention the Zuma/kymco forums.

[superdan54]

Wow you were spot on there!

They reeds were pretty bent (are they supposed to be completely straight initially?). Unfortunately they are irregularly shaped so that it only fits in one direction, so I don't think I can flip them over without having to cut some steel. It's ok though, the intake gasket was really crusty and fell apart when I initially took it off so I'll need to order that as well. Do you think this could also cause the starting problems I mentioned in the OP?

Thanks again for your sage advice!

[zombie]

Starting is when they are MOST prone to show a problem as they are not really closing till higher rpm's. I have a glass table that I use to check things for TRUE. They should be flat as glass. Do your self a favor, and get the "o" ring for the oil pump too. Since the gasket fell apart I would guess the "o" ring to be dry rotted too. One bolt to pull the pump out.
 I'm gonna post a link.... We should get paid for this sh*t!

[superdan54]

Ugh...I'm such a dunce. So it wasn't the reeds that were bent, it was the reed stopper plate that was bent...as it presumably should be. The actual reeds looked ok though, no cracking or bending. OH well, live and learn.

Sorry for the false positive...anything else I should look at? I will also check out that o-ring on the oil pump. Thanks!

[zombie]

Look w/ a magnifying glass at the reed cage. You may have cracks or fractures in it. The only way for oil/fuel to splash back is thru there. I would still replace them w/ either Malossi, or the fiber blank but the cage may be cracked/warped. Do a compression test too. That tells more about the inside condition of the engine than any other method. You'll want at least 120 psi on the gauge.