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Post by rock on Mar 9, 2015 20:42:48 GMT -5
Hey guys, as a relatively new member of this community I was wondering if I could enlist the help of some of you in answering a question that I have. I recently was given a scooter with less than 30 km on it, only problem is that it had been sitting for nearly 3 years. I have cleaned everything (carb,air box, etc) and replaced most fuel and vacuum lines. It now starts and idles great. My problem begins when you give it throttle. Once it gets revved over about 2000 rpms the engine seemingly floods and shuts off. I need to know what the problem is and how to fix it. Is the air/fuel mixture too rich? Too lean? Or is it something else? I am really looking forward to getting this thing in tip top shape and maybe even some upgrades on it but this definitely has me stumped. Any and all help is appreciated.
Thanks guys,
Rock
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Post by jerseyboy on Mar 9, 2015 21:14:37 GMT -5
Did you clean the pet cock or fuel pump out too,,after you cleaned carb did you put the A/F screw back to where it was,if not start out about 2 turns out and follow Alleys tuning guide?
I would check fuel delivery to carb from tank,,pull the fuel line off the carb and put it in a small coffee can,,then crank the motor over,,does fuel spurt out good?
If so,,then you have good delivery,,you problem lies downstream from here,,could be a clogged port in the carb,,you really need to spray all of those small pin holes really good with cleaner and run a steel guitar string or piece of a wire brush through them,,make sure when you spray cleaner up through pilot jet and main,,it sprays out the ports on the intake side by butterfly..they are tiny...
How does the plug look,,wet or dry?
Thats where I would start,,if all that is good you may have an electrical issue..Ive seen a failing coil cause a stall under load.
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Post by rock on Mar 9, 2015 23:05:55 GMT -5
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I did not clean the petcock. After I cleaned the carburetor I turned the screw back to where it was to the best of my knowledge. I will clean the petcock and adjust the A/F screw before I check delivery. If that fails I will take your advice and clean the carb. The plug is wet (I don't know if that's good or bad)
I want to thank you for your help. I greatly appreciate it and look forward to getting to know more about this community and the people in it.
Rock
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Post by JoeyBee on Mar 9, 2015 23:17:04 GMT -5
A wet spark plug may indicate a problem.  |
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Post by rock on Mar 9, 2015 23:29:02 GMT -5
How would one fix this issue? If this question has already been answered you can just link me to it or I can go find it.
Thanks again,
Rock
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Help a Newbie
by: JoeyBee - Mar 10, 2015 0:24:41 GMT -5
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Post by JoeyBee on Mar 10, 2015 0:24:41 GMT -5
First question is about how you cleaned the carburetor. When you cleaned it, did you remove both the pilot and main jets to ensure no blocked. This is done by spraying carb cleaner through both and holding them up to the light to ensure no blockage.
Next question would be the cc of the scooter (50/150/250) and the size of the main jet. This number is usually stamped on the head of the jet.
From what you are describing the carb is performing well during idle. But once the carb transitions from the pilot jet to main jet maybe it's clogged or oversized. If it's wet as described probably oversized.
The engine size, jet size, and picture will help the process of getting the scooter operating properly.
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Post by JerryScript on Mar 10, 2015 1:00:30 GMT -5
One other thing we need to know, are you running the stock airbox and filter, or a uni or some other after market air filter unit, and have you made any changes to it recently.
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Post by rock on Mar 10, 2015 16:08:16 GMT -5
The engine is a stock 150 cc GY6 engine with no upgrades whatsoever on it. The CDI, coil, and spark plug are stock as well. The stock air box is being used and the only thing I have done with that is remove it to ensure that it was still in working condition and reinstall it. The main jet is stamped as a 75. I don't know the size of any of the other jets or components on the carburetor. If cleaning the carb again just to be sure is recommended then I can definitely do that as well as cleaning the petcock. Again, the spark plug is slightly wet with oil upon inspection.
Thanks,
Rock
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Post by JoeyBee on Mar 10, 2015 16:43:43 GMT -5
The engine is a stock 150 cc GY6 engine with no upgrades whatsoever on it. The CDI, coil, and spark plug are stock as well. The stock air box is being used and the only thing I have done with that is remove it to ensure that it was still in working condition and reinstall it. The main jet is stamped as a 75. I don't know the size of any of the other jets or components on the carburetor. If cleaning the carb again just to be sure is recommended then I can definitely do that as well as cleaning the petcock. Again, the spark plug is slightly wet with oil upon inspection. Thanks, Rock A 75 main jet is extremely too small for a 150cc. With all stock the main jet should be 100-104. That may be the problem. Maybe someone replace the carb but installed one for a 50cc instead of 150cc. |
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Help a Newbie
by: geh3333 - Mar 11, 2015 20:49:42 GMT -5
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Post by geh3333 on Mar 11, 2015 20:49:42 GMT -5
The engine is a stock 150 cc GY6 engine with no upgrades whatsoever on it. The CDI, coil, and spark plug are stock as well. The stock air box is being used and the only thing I have done with that is remove it to ensure that it was still in working condition and reinstall it. The main jet is stamped as a 75. I don't know the size of any of the other jets or components on the carburetor. If cleaning the carb again just to be sure is recommended then I can definitely do that as well as cleaning the petcock. Again, the spark plug is slightly wet with oil upon inspection. Thanks, Rock A 75 main jet is extremely too small for a 150cc. With all stock the main jet should be 100-104. That may be the problem. Maybe someone replace the carb but installed one for a 50cc instead of 150cc. Wow , if its really a 75 , I hope I wasn't running too lean too long . you may have a bigger issue . maybe someone drilled the 75 out to a bigger size ? At this point the best thing to do is order a new set of stock jets for the carb . |
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Post by rock on Mar 23, 2015 20:15:21 GMT -5
A 75 main jet is extremely too small for a 150cc. With all stock the main jet should be 100-104. That may be the problem. Maybe someone replace the carb but installed one for a 50cc instead of 150cc. Wow , if its really a 75 , I hope I wasn't running too lean too long . you may have a bigger issue . maybe someone drilled the 75 out to a bigger size ? At this point the best thing to do is order a new set of stock jets for the carb . You guys hit it right on the nose. I threw a 105 and a different idle jet in there and it did the trick. Now I just have to dial in the idle. Can somebody link me to "Alley's" A/F mixture guide? I've seen it before but I can't seem to find it now. The exhaust is really dirty on idle and rpms are low. But the good news is that it no longer bogs out after the clutch engages. Thank you guys so much! |
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Post by JerryScript on Mar 23, 2015 20:19:47 GMT -5
Wow , if its really a 75 , I hope I wasn't running too lean too long . you may have a bigger issue . maybe someone drilled the 75 out to a bigger size ? At this point the best thing to do is order a new set of stock jets for the carb . You guys hit it right on the nose. I threw a 105 and a different idle jet in there and it did the trick. Now I just have to dial in the idle. Can somebody link me to "Alley's" A/F mixture guide? I've seen it before but I can't seem to find it now. The exhaust is really dirty on idle and rpms are low. But the good news is that it no longer bogs out after the clutch engages. Thank you guys so much! Here you go: itistheride.boards.net/thread/12/4ts-carb-tuning?page=1 |
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Help a Newbie
by: geh3333 - Mar 23, 2015 20:35:24 GMT -5
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Post by geh3333 on Mar 23, 2015 20:35:24 GMT -5
Wow , if its really a 75 , I hope I wasn't running too lean too long . you may have a bigger issue . maybe someone drilled the 75 out to a bigger size ? At this point the best thing to do is order a new set of stock jets for the carb . You guys hit it right on the nose. I threw a 105 and a different idle jet in there and it did the trick. Now I just have to dial in the idle. Can somebody link me to "Alley's" A/F mixture guide? I've seen it before but I can't seem to find it now. The exhaust is really dirty on idle and rpms are low. But the good news is that it no longer bogs out after the clutch engages. Thank you guys so much! TBA its really easy to remember if you break it down to the nuts and bolts of it. First let the scoot warm up , next set the idle screw so the scoot idles around 2000 rpms. Next turn the air fuel to the right until the idle begins to drop then turn the air fuel back until you get the highest idle. After that lower the idle screw until the scoot is idling around 1700 rpms. Very simple. Just be careful the scoot doesn't start to idle too high or it may take off on you . if I begins to idle too high drop the idle screw back down until you reach 2000 rpms and proceed with adjusting the air file to the highest idle. |
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Help a Newbie
by: JoeyBee - Mar 23, 2015 20:58:12 GMT -5
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Post by JoeyBee on Mar 23, 2015 20:58:12 GMT -5
rock. That's good to hear you got it up and running. I was starting to wonder if the jets were the problem. Go step by step through the carb tuning guide by alleyoop and you won't have a problem. Now that it is warming up I am loving my night time ride to work. Keep us updated, and ride safe.
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Post by rock on Mar 23, 2015 23:18:41 GMT -5
rock. That's good to hear you got it up and running. I was starting to wonder if the jets were the problem. Go step by step through the carb tuning guide by alleyoop and you won't have a problem. Now that it is warming up I am loving my night time ride to work. Keep us updated, and ride safe. Will do  . This community and forum are both great places and I plan to be here for a while. Thanks for all of your help with everything. Hope to see you around. |
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