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Post by dakotafig on May 24, 2013 23:19:22 GMT -5
I realized I haven't been around here in a while when I tried to log into SD and it was closed up.  Anyway, I purchased my 150 with 50 miles on it. I bought a new Jap carb right away, adjusted the valves, put a new spark plug in it and got rid of the emissions crap. It has been running great until a week ago. Now it has a dead spot in the throttle and it is there if I am speeding up or slowing down. What I mean by dead spot in the throttle is this, I will be running along at a constant speed and slow down some by backing off on the throttle and it will suddenly fall on its face. If I continue to back off the throttle it will come to life again. Or if I increase the throttle it will pick back up again as well. I have checked all the hoses for vacuum leaks, checked the inlet tube between the carb and the intake and I took the carb apart and it looks really, really clean with no holes in the diaphragm. It seems to feel like a vacuum leak since the idle tends to hunt around a lot now. It seems really strange because it was running great and then all of the sudden this happened. At wide open throttle it still seems to run good with plenty of power. I'm kind of at a loss. I'm thinking I might go ahead and change the plug again just for good measure, and maybe put better clamps on the vacuum tubing. However, I started it up and sprayed starting fluid on all the hoses and it never changed rpm from that once. Am I missing something simple? |
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Post by skuttadawg on May 24, 2013 23:30:25 GMT -5
Have you looked at the needle clip ? What size venturi and jet sizes ? Was the old carb bad ? Did it do this way with the old carb ? Exhaust leak ?
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Post by alleyoop on May 24, 2013 23:39:33 GMT -5
If the idle is bouncing it is LEAN,
First check for AIR LEAKS, cracked Air Tube going to the carb open connectors on the air box, Cracked Intake Manifold, Loose Clamps holding the Carb etc..
If no leaks then:
If your carb has a FUEL RATIO screw Turn it COUNTER CLOCKWISE.1/4 at a time and test it.
If your carb has a AIR RATIO screw Turn it Clockwise 1/16-1/8 at a time does not take much and test it.
Alleyoop
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Post by dakotafig on May 25, 2013 13:19:28 GMT -5
What do you mean the clip that holds the needle to the float in the carb? That all looked great. I just wanted to start with all the obvious stuff like vacuum leaks. However, as I said, I didn't find any smoking gun. I will put it all together and try adjusting the carb this afternoon. As far as what size jets, I have no idea to be honest. Should be the stock size. I just bought the carb on eBay and put it on.  |
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Post by alleyoop on May 25, 2013 13:36:22 GMT -5
Scuttadawg is talking about the Needle on the Cylinder Slider, If the needle has slots it has a "C" clip that you can it down 1 slot to raise the needle a hair which allows a little more fuel to come in around the mid-range. Alleyoop  The needle with "C" clip and slots and how to adjust for leaner or richer mid-range:  |
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Post by gy6girl on May 25, 2013 14:01:20 GMT -5
When you say, "suddenly fall on its face", do you mean stops firing?
Like no combustion of the fuel, then away from the dead spot, it starts firing again?
That's an odd one.
Could it be the electronics in the CDI not working at certain rpms?
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Post by dakotafig on May 25, 2013 14:10:03 GMT -5
I don't remember seeing a c clip like that. I don't think mine is adjustable.
It is still firing, I think anyway. It just seems like there is suddenly no fuel in a certain spot in the throttle. It's not always the same all the time either.
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Post by brandjur on May 25, 2013 23:05:06 GMT -5
I purchased a newer carb and had to use 2 washers from Home Depot as spacers to adjust the mixture richer. Attachments:
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Post by dakotafig on May 26, 2013 14:58:31 GMT -5
Well, here is an update. I put everything back together and gesh, it was running worse. I tried to adjust the carb but it didn't matter, the RPM's fluctuated up and down now matter what I did with the mixture adjustment screw. And, attempting the adjustment didn't impact the rpm one way or the other. I even zip tied the vacuum line connections.
I pulled the plug out and it actually looked really good, but, the top connection felt really loose to me. So, I'm going to get a new plug and wire, and I guess go with a new carb. It is kind of strange how this seemed to come on pretty fast.
I did find where my inlet tube from the air filter to the carb has been rubbing on the idle speed adjustment screw, but it hasn't worn a hole through it yet. I would love to upgrade the air filter box and tube, but one issue at a time.
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Post by dakotafig on May 26, 2013 15:11:22 GMT -5
Well, I guess a quick search I find out that the coil and wire are all one. I have seen several people selling the "performance" coil, wire and CDI box. Are they worth it?
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Post by alleyoop on May 26, 2013 15:15:39 GMT -5
The BOOT CAP and Wire are screw on types, you can replace the BOOT CAP they sell those seperate. Just a question where you adjusting the IDLE SPEED SCREW by the THROTTLE CABLE or the FUEL RATIO MIXTURE screw on the LEFT SIDE(kickstand side)? If turning the FUEL RATIO MIXTURE in EITHER DIRECTION did not EFFECT the IDLE UP OR DOWN, The Pilot JET and OR it passage are CLOGGED. Alleyoop  |
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Post by dakotafig on May 26, 2013 15:48:16 GMT -5
Sorry for confusing the previous post. I meant adjusting the mixture screw on the kick stand side. I edited my post above to fix my error. Anybody have a recommendation for a good carb? I don't remember where I got the one before. There are tons of them on eBay and Amazon.
Also, the forum won't let me search for jet sizes because it keeps kicking out the term Jet since it is less than 4 letters. So, if I replace or go through my existing carb, what would be the recommendation for the main jet size?
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Post by alleyoop on May 26, 2013 16:01:58 GMT -5
Your not listening or reading what I said, You just said that turning the FUEL RATIO MIXTURE did NOT EFFECT the IDLE UP OR DOWN. YOU need to clean the PILOT JET make sure you can see daylight through it and CLEAN OUT THE PASSAGE. Get a Spray can of CARB CLEANER they come with a long thin straw to get into small places. Take the PILOT JET out clean that out and look through it and you should see daylight. Then stick the THIN STRAW into where the PILOT JET SCREWS into and spray and here is where spray should come out. You do not need another carb, unless you messed this one up somehow: Here you can get a bigger jet size, the 150s come with a 24mm carb and the jets are usually not marked but the stick anywhere from 103-107 main jet in them so you really do not know what is in there unless of course it is marked. www.testedscooterparts.com/advanced_search_result.php?keywords=24mm+carb&searchop=or&osCsid=460c68cc68a225402a7d90c356d06627&x=10&y=9Alleyoop  |
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Post by dakotafig on May 27, 2013 14:14:18 GMT -5
Ok, I took the carb apart this afternoon and here is what I found. There probably was a tiny, tiny bit of gunk in the pilot jet. I have it cleaned out. The main jet looks real good. It is stamped with a 103. I would like to get a conical filter, and if I did that, what do you suppose I should start out with jet size?
Also, I pulled my slide apart, and I do have the adjustable needle as alleyoop showed in the red picture above. And, I am in the exact same slot as the picture. I wanted to look just to know for sure, but I don't think I will change it for now because before a few days ago it was actually running pretty good across the entire power band.
Lastly, one thing I just thought of, I have the rattling muffler syndrome. I don't think it is causing problems besides just noise, but I suppose that could be doing funking things with back pressure at different RPM's. I looked for mufflers a while back, but I gave when everything is $100 or more.
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Post by dakotafig on May 31, 2013 22:36:58 GMT -5
Ok, I finally got the new coil and wire in today, and I have a new 125 jet in hand. I was working on cleaning out the carb and putting it back together when I came up with a question. Where exactly does the needle on the slide meter the fuel? The tip of the needle is a long ways away from the jet itself and I'm assuming the body of the needle farther up is where it is metered.
Also, the o-ring for the carb bowl has shrunk and doesn't want to fit in the slot for it. I have read that soaking it in Kerosene will make it expand slightly. Anyone ever done that?
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..BAD TO THE BONE..
MJ, Orange coil, Blue Performance CDI (Orange NCY did not work), NGK Iridium, 5g Sliders