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Post by rippinryno on Jun 1, 2016 6:48:55 GMT -5
Hey guys, i'm new here. First off, i'm familiar with small engines and atv motors so this is all pretty basic to me.
My scooter was bogging and then eventually got to the point where it would only accelerate at about 1/10 of throttle turn. I ordered a new vacuum pump and put some new fuel lines on and filter as well as flushed the tank. The carb got cleaned and it actually looked spotless. I pulled the jets and made sure they were all clear, things looked good. When i got the new vacuum pump the motor fired right up but I still have this slight bog when i'm trying to accelerate under full throttle. It basically lurches and surges from a stop to about 10mph. Once i get it giong it will wind out and run perfect. I spent about an hour yesterday adjusting the a/f screw and trying to find a sweet spot. It seems to run best at about 1.5 turns out, but even then i have this bog under acceleration. I've not been able to determine what the cause of this is, i'm almost wondering if this is all the better the little china scooter can run.
Spark plug is not fouled, i purchased 2 of them when i got the scooter and have not noticed any change in putting a new one in. Air filter is spotless, vacuum lines look good, intake is in tact and not leaking. I've got a full tank of gas, fresh oil and fresh trans oil as well.
anything i'm missing to try to fix this or do i just have to live with it?
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Post by JerryScript on Jun 1, 2016 9:20:34 GMT -5
Welcome to the board!
For problems so early in the acceleration curve, first try putting more bend in the accelerator pump spring (if you have one), they often get bent out when handling the carb during cleaning. If that doesn't fix the problem, check your diaphragm for tears, and if the needle is adjustable, raise it by lowering the clip or adding a washer.
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Post by scootdoggydog on Jun 1, 2016 12:17:43 GMT -5
When was the last time you checked the valve gaps?
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Post by rippinryno on Jun 1, 2016 21:05:15 GMT -5
Thanks guys I'll check the carb again. I don't believe I have an accel spring but could be wrong. This is a gy6 clone basically. I've not checked valve clearance and wouldn't suspect that to be a cause but it wouldn't hurt so I'll do that too. Any idea where they need to be?
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Post by JerryScript on Jun 1, 2016 21:44:59 GMT -5
Set both to .004"-.005", some set the exhaust on step above the intake.
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Post by rippinryno on Jun 2, 2016 6:22:57 GMT -5
I am certain that you mean .004 inches and .005 inches not mm right?
I will go ahead and check the valves to at least get them within spec, if they arne't already, i don't believe them being out of spec would cause low end bog like what i'm getting though.
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Post by pistonguy on Jun 2, 2016 10:08:45 GMT -5
I am certain that you mean .004 inches and .005 inches not mm right? I will go ahead and check the valves to at least get them within spec, if they arne't already, i don't believe them being out of spec would cause low end bog like what i'm getting though. Yes, you are correct Inches. .004" & .005" |
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Post by JerryScript on Jun 2, 2016 12:28:16 GMT -5
Yep, thanks for catching the typo, edited above to fix.
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Post by urbanmadness on Jun 2, 2016 17:48:22 GMT -5
also check the intake manifold for cracks.... and look for other assorted vacuum leaks.
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Post by rippinryno on Jun 6, 2016 7:28:37 GMT -5
Quick follow up guys. I went ahead and adjusted teh valves, they seems a bit tight so i set them to .005, now i notice i have some valve tick so i'm going to tighten them back to around .004. Anyway nothing changed when I adjusted the valves so I still have the same problem. Does anybody know what size jets this carb should have stock? i pulled the needle and it has 3 clip settings so I put it down on the bottom setting and my problems did not get any better. Tonight i will try to go all the way up on the needle clip setting and see if that helps. It was on the middle one to begin with. I can baby the throttle and get it to take off if i only turn about 1/4 throttle, anything after that and it really wants to bog and almost die.
I hate to buy a new carb, but i am wondering about the enricher/choke setup and the jets in this carb if it was messed with they may not be what they need to be.
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Post by scootdoggydog on Jun 6, 2016 18:15:29 GMT -5
I think stock carbs come with a main jet in the 104-107 range. Are you getting a good spark what does your tach read when it bogs does it drop slowly or completely?
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Post by hillbillybob on Jun 6, 2016 18:55:48 GMT -5
Sure sounds like an accelerator pump problem. Think I would spend the $21 for a new carb......then fiddle around with the one you have now, if you want to have a spare handy. 50cc Carb |
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Post by rippinryno on Jun 8, 2016 7:30:28 GMT -5
i don't have a tach on this, but in my experience this definitely seems like some sort of fuel issue. I dropped the needle back down to the middle setting and did some tweaking. I'm now able to ride it and as long as i don't turn more than 1/2 throttle on acceleration it will take off, once it gets going i can give it full throttle. I do believe I will try a new carb.
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