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-   -   Main Jet Upgrade did not work at all (http://www.scootdawg.net/showthread.php?t=55830)

Mäwby 07-17-2017 09:56 AM

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?

wheelbender6 07-17-2017 07:38 PM

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.

rks 07-18-2017 06:55 AM

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.

Mäwby 07-18-2017 12:05 PM

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.

wheelbender6 07-18-2017 07:51 PM

The carb on my 125Cc scoot is a Keihin clone, so my jet numbers correspond to different sizes than your gy6.

rks 07-19-2017 07:06 AM

Quote:

Originally Posted by Mäwby (Post 535887)
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.

http://scootdawg.net/picture.php?alb...&pictureid=550

Mäwby 07-19-2017 12:11 PM

Quote:

Originally Posted by rks (Post 535892)
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.

http://scootdawg.net/picture.php?alb...&pictureid=550

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


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