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Old 07-17-2017, 09:56 AM   #1
Mäwby   Mäwby is offline
 
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Main Jet Upgrade did not work at all

I tried rejetting two carbs I have. When trying different jets, all led to the scooter bogging down under full throttle. The only jet I have that works properly is not marked so I don't know what size it is. I have a 24mm and 26mm carb. The unmarked jet works best in the 26mm carb. Any ideas of why the other jets led to the bogging down in both carbs?



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Old 07-17-2017, 07:38 PM   #2
wheelbender6   wheelbender6 is offline
 
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Can you tell by looking at the holes if the numbered jets are bigger than in the original un-numbered jet? You may be able to see that with a magnifying glass.
-Did you take a look at your spark plug tip after running the numbered jets to see if they made your insulator darker or lighter?
-jetting is really trial and error, but spark plug readings can speed up the process a lot.
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Old 07-18-2017, 06:55 AM   #3
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What size jets have you tried? What other changes have been made to your intake/exhaust system? Since you mentioned 24 and 26 mm carb....I presume it's a 150cc scoot.

If the unmarked jet is the original, it is probably in the 105 to 108 range. If you are changing it out with a 120 or larger, is no wonder you're having problems. Need more info from you, to be helpful.
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Old 07-18-2017, 12:05 PM   #4
Mäwby   Mäwby is offline
 
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Thanks for the replies guys. I was trying the larger jets, which is probably why it was bogging down. I'm still learning, so forgive me. I had the mentality that larger jet means more fuel, more power. But it looks like the 105 range is where I belong.
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Old 07-18-2017, 07:51 PM   #5
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The carb on my 125Cc scoot is a Keihin clone, so my jet numbers correspond to different sizes than your gy6.
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Old 07-19-2017, 07:06 AM   #6
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Quote:
Originally Posted by Mäwby View Post
Thanks for the replies guys. I was trying the larger jets, which is probably why it was bogging down. I'm still learning, so forgive me. I had the mentality that larger jet means more fuel, more power. But it looks like the 105 range is where I belong.
A good indicator of how lean/rich your fuel mixture is, as wheelbender6 said, is the spark plug. You're looking for a tan color around the center electrode. White is too lean, black is too rich. This was my plug at 4,500 miles, back in Aug of 2014.....put it back in and ran it to 12,000 miles. Replaced with a new one late this spring.

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Old 07-19-2017, 12:11 PM   #7
Mäwby   Mäwby is offline
 
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Originally Posted by rks View Post
A good indicator of how lean/rich your fuel mixture is, as wheelbender6 said, is the spark plug. You're looking for a tan color around the center electrode. White is too lean, black is too rich. This was my plug at 4,500 miles, back in Aug of 2014.....put it back in and ran it to 12,000 miles. Replaced with a new one late this spring.

Awesome! Thanks. I'll check my today when I get off of work.
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