Starter Jet for Big Bore

Should the starter jet size be decreased after installing a big bore kit due to increased vacuum from the larger piston?

Bike in question here is an '05 yz250f which has been bored 3mm over to ~270cc. Stock starter jet is a 72.

Should the starter jet size be decreased after installing a big bore kit due to increased vacuum from the larger piston?

Bike in question here is an '05 yz250f which has been bored 3mm over to ~270cc. Stock starter jet is a 72.

Interesting question, if it is too big it just means you will be taking it off choke sooner after starting. I have gone the otherway, my 450 Husky (bigger version of the same carb) came with an 80, I got tierd of waiting for it to start on cold mornings and went to a 105, no way is it a "too aggressive of choke" problem.

i would not make any jetting changes until testing your current setting first.

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