New air filter=Bad Performance?

I custom made a new air filter for my Baja SC50, 4 stroke 50 cc Chinaped. After I put it on, it ran really sluggish and I couldn't get it above 25. I thought it would improve my power, which I need since I live on a steep hill, but it made it worse! I figured it was running too lean with all the air it was getting, but I have no idea what size jet I should go up to. Right now the main jet is a 138 I think? Also do I need to replace any other jets. Can anyone help me with this? I really want to get out and ride!

Re: New air filter=Bad Performance?

Common question - you'll want to upjet. Try getting a jet thats 2-4 sizes bigger, and test it out. You wont want to run it much with out upjetting - your running too lean and could freeze up your motor.

I tried the same thing - a custom intake - and went back to the old intake until I could get the correct jet.

Re: New air filter=Bad Performance?

Oh ok cool. If I drill my old jet out, do I drill both the idle and main jets or just the main? Oh and how much should I drill it out?

Re: New air filter=Bad Performance?

drilling is risky - you can't be too exact. its kind of guess and check - and if you go too big you cant go back you know?

if your ideling fine, then dont worry about that. if your only having problems (4 stroking) when giving it gas, drill the main jet. but making each jet bigger is not a bad idea at all.

either way, wheather idling or giving it gas, your motor is still sucking in more air, so both for idle and giving gas, you require more fuel.

if i were you, i'd just buy some more jets and go from there. but that takes time and patience, something i dont have much of =)

Re: New air filter=Bad Performance?

if ya drill too big you can solder the hole up and redrill

Re: New air filter=Bad Performance?

Wow! Al ot of great ideas. I think I'll hit up some power shops near my house. Hopefully I'll be back on the road soon. Tnaks again to everyone who gave advice, and if you have more, feel free to drop it my way. I'll keep checking this.

Re: New air filter=Bad Performance?

Oh by the way, does a 138 sound like a real main jet size? It was a number stamped on the top of the main jet, so I kinda...assumed.

Re: New air filter=Bad Performance?

either it has a big carb on it or they use some funky jet numbering scheme..

Re: New air filter=Bad Performance?

it's a four-stroke, and it's a scooter.... (not a moped) so i would bet that things will be different.. (main jet sizes and such)

Re: New air filter=Bad Performance?

Okay, I'll probably just take the idle and main jets with me when I go to the parts shop and ask what the size is. Thanks again.

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