Help with carb re jet

[an1theboot]

I have no local shops or mechanics willing to work on my GY6 50cc scooter. I have added performance exhaust,and removed stock air box. I was in unaware of me needing to re jet my carb. Any suggestions on the jet sizes needed? I’m at about 1100 above sea level. Any help would be greatly appreciated. Thanks

[Zino]

What size jet and type do you have now in your carb ?
Are you on a open filter ?

You will need to get a range of jets .

4 strokes dont require as extreme in jetting change that the 2 strokes need.
On a 2 stroke with open filter i would have you start 20 % bigger and work your way down from gurgly rich till it cleans up .
4 strokes dont need that big of jump
So I would start at 10 % higher swap in a fresh plug run around the block see how it feels and check plug color .
Dark plug and Doggy feel drop down a jet till it is not Doggy .

I need one of the 4 stroke guys to chime in to give better guidance .

[an1theboot]

Sept 3, 2020 16:42:23 GMT -5 Zino said:

What size jet and type do you have now in your carb ?
Are you on a open filter ?

You will need to get a range of jets .

4 strokes dont require as extreme in jetting change that the 2 strokes need.
On a 2 stroke with open filter i would have you start 20 % bigger and work your way down from gurgly rich till it cleans up .
4 strokes dont need that big of jump
So I would start at 10 % higher swap in a fresh plug run around the block see how it feels and check plug color .
Dark plug and Doggy feel drop down a jet till it is not Doggy .

I need one of the 4 stroke guys to chime in to give better guidance .

Stock main right now is 72. And yes open filter.

[mikehailwood]

Also, how does it run now compared to before changes were made?

[an1theboot]

Sept 3, 2020 18:54:07 GMT -5 mikehailwood said:

Also, how does it run now compared to before changes were made?

lots of black smoke. Fuel smell. When I give it throttle has some hesitation and then bogs down pretty bad and shuts off eventually.

[Zino]

bogging black smoke you are rich
look at plug see if it is black already
you might be down jetting instead

[an1theboot]

Ok so I got all the fuel smell and smoke under control. Now my question is. After I’ve put on new exhaust, new transmission kit,CDI BOX and new air filter. Why has it not changed one thing of how my scooter was running. Like literally no speed increase at all. Only thing I gained was my take off and well the sound from new muffler.

[FrankenMech]

There is no speed increase because the stock setup from the manufacturer was fairly optimum in the first place. The OEM has a good reason to get the best performance out of his product as he can without exceeding the statutory laws that regulate performance for the model.

[GrumpyUnk]

Sows ear<> silk purse. Translated: You own/posses a cheap scooter. It will not perform like a larger, more expensive scooter. You may see some marginal gains with air intakes and exhaust changes, but my opinion is they are 'seat of the pants performance' but may not be measurable.
Only way to increase performance is to increase power, which means displacement, for the most part. once you do that, you run into other limitations that either need changed parameters(CVT weights/belt/springs/etc) or more new parts(carb/exhaust/??)
If you have black smoke and semi-carboned-up spark plugs, you are likely too rich. OR, the float is not working properly to limit the level of fuel in the float bowl, again causing a too-rich mixture.
A 72 is surprising to me, as I would have expected closer to a 90 size. Is it possible someone adjusted the jet size using a drill, and it is no longer actually a 72?
tom

[an1theboot]

Sept 5, 2020 11:01:58 GMT -5 GrumpyUnk said:

Sows ear<> silk purse. Translated: You own/posses a cheap scooter. It will not perform like a larger, more expensive scooter. You may see some marginal gains with air intakes and exhaust changes, but my opinion is they are 'seat of the pants performance' but may not be measurable.
Only way to increase performance is to increase power, which means displacement, for the most part. once you do that, you run into other limitations that either need changed parameters(CVT weights/belt/springs/etc) or more new parts(carb/exhaust/??)
If you have black smoke and semi-carboned-up spark plugs, you are likely too rich. OR, the float is not working properly to limit the level of fuel in the float bowl, again causing a too-rich mixture.
A 72 is surprising to me, as I would have expected closer to a 90 size. Is it possible someone adjusted the jet size using a drill, and it is no longer actually a 72?
tom

[an1theboot]

Sept 7, 2020 14:45:55 GMT -5 an1theboot said:

Sept 5, 2020 11:01:58 GMT -5 GrumpyUnk said:

Sows ear<> silk purse. Translated: You own/posses a cheap scooter. It will not perform like a larger, more expensive scooter. You may see some marginal gains with air intakes and exhaust changes, but my opinion is they are 'seat of the pants performance' but may not be measurable.
Only way to increase performance is to increase power, which means displacement, for the most part. once you do that, you run into other limitations that either need changed parameters(CVT weights/belt/springs/etc) or more new parts(carb/exhaust/??)
If you have black smoke and semi-carboned-up spark plugs, you are likely too rich. OR, the float is not working properly to limit the level of fuel in the float bowl, again causing a too-rich mixture.
A 72 is surprising to me, as I would have expected closer to a 90 size. Is it possible someone adjusted the jet size using a drill, and it is no longer actually a 72?
tom

I bought this brand new so nothing was done to it beforehand. Stock was a 72 was told to jump to 85 by someone. It kinda sucks. I was at 35-38 stock and with everything I did I’m still only at 40-43 max. I think it’s time to sell it and get something else.

[mikehailwood]

If that's 40-43 mph, that would be very good for 50cc. If it's 40-43 kph, I would be disappointed.