Free and Inexpensive Scooter Performance Mods

[TBR125]

When pulling the scooter air box I came across several breathers that I rerouted into a filtering reservoir but one hose leading into the intake baffled me. Come to find out after several hours of searching with various keywords it is a charcoal filter for the fuel vent line. After looking at what it controlled I pulled the unit and routed the vent line through the body panel above the fuel tank. It works fine and pulled 2 pounds off the bike.

[TBR125]

Here's the rerouted vent line.

[jeeves]

My carburetor is re-jetted! I swapped the main and pilot out a few times with test rides in between and settled on a 115 main and a .38 pilot. I will take a long ride tomorrow to finalize the tuning.

As a side note, I always expect a job to be harder than first thought, but still, the carb tuning was the most complex thing I've ever done to the bike. I feel a tad bit invincible. I will have performance data tomorrow and will see what the 56 dollars for jets, air intake, and muffler really did.

The original main is 105?

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[TBR125]

Sorry I didn't mention that. The original main is 102 with a 0.35 pilot. Remember I have the agility 125 but not the city. Jets may differ slightly.

[jeeves]

Sorry I didn't mention that. The original main is 102 with a 0.35 pilot. Remember I have the agility 125 but not the city. Jets may differ slightly.

Thanks!
I also changed the pilot from 0.35 to 0.38 hoping that more fuel would eliminate backfires at rapid declaration, but that didn't happen.
It did get a bit easier to ride 2 up.
Fuel consumption went up as well.

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[TBR125]

I've got the .38 pilot as well. For me the backfiring disappeared but I don't know what did it. Those jets may not be my final choice until I put some miles on the bike. What baffles me is now the bike idles super rich even with the screw maxed lean. I would think it would idle lean with the larger filter flow.

[jeeves]

Idle screw should be around 2.5 turns out when all stock.
Can't remember at what position mine is now.
I know that I fiddled with it when I changed the exhaust, and somehow during a ride the idle screw fell out! The scooter couldn't idle properly, but would run ok when the revs went up.
Couldn't believe that it fell off [emoji23]

So I put a new one in (luckily I had a spare one at home), and didn't mess with it any more.

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[TBR125]

Oh, I was not referring to the idle speed screw but the idle fuel mixture screw. It is located on the engine side of the throttle butterfly valve increasing or decreasing fuel to air ratio at closed throttle. I set the idle speed screw at 1700rpm as is spec.

[jeeves]

Yes, I lost that screw!

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[TBR125]

Ouch.