2025 Apollo 250 thunder What size jets in nibbi 28mm ???

Dirtrace25@aol.com · Today, 08:43 AM

Hello all, I recently purchased 2 Apollo RFX 250 thunder bikes. Purchased the recommended nibbi 28mm carbs . They run 75% better but still have a bad bog when you go from idle to wide open throttle. The carbs came with different size jets main and pilot. Can anyone tell me which size jets work best in these bikes ?

Thumper · Today, 11:13 AM

Try lifting or dropping the needle. If improved dropping it (less fuel), but still bogs once at high rpm, then too rich on the main. If it improves with needle lifting higher but still bogs at high rpm WOT, then probably a bit lean at the high end...increase the main jet size.

My point is you have an assembled carb not working at its best. Open it up and note the existing jets and move the needle one way or the other. Also, have you adjusted the airscrew? Is it exposed?

Today, 08:43 AM	#1
Dirtrace25@aol.com Join Date: Nov 2024 Location: Georgia Posts: 4	2025 Apollo 250 thunder What size jets in nibbi 28mm ??? Hello all, I recently purchased 2 Apollo RFX 250 thunder bikes. Purchased the recommended nibbi 28mm carbs . They run 75% better but still have a bad bog when you go from idle to wide open throttle. The carbs came with different size jets main and pilot. Can anyone tell me which size jets work best in these bikes ?
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Today, 11:13 AM	#2
Thumper Join Date: Feb 2021 Location: Kansas City Posts: 2,739	Try lifting or dropping the needle. If improved dropping it (less fuel), but still bogs once at high rpm, then too rich on the main. If it improves with needle lifting higher but still bogs at high rpm WOT, then probably a bit lean at the high end...increase the main jet size. My point is you have an assembled carb not working at its best. Open it up and note the existing jets and move the needle one way or the other. Also, have you adjusted the airscrew? Is it exposed? __________________ No matter where you go, there you are Last edited by Thumper; Today at 01:43 PM.
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