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Discussion Starter · #1 ·
I bought a 2005 raptor 660 and have been chasing problem after problem. It has a no lid air box with a slip on. Sadly I bought it with a Chinese carb on it. It idles really well but can’t give it ANY throttle without it bogging and backfiring. I have stock jets in it with the needle position at 2. Also I’m at 6,000 ft elevation. Just looking for some help to see if I can get this carb to work before I buy an OEM one. Thank you in advance!
 

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Master of the Electron
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Welcome to the forum!

At 6000 feet you'll want 2 or 3 sizes smaller on your main jets. With your mods (at sea level) I'd recommend 155 in left and 160 in right carbs... but at 6000 I'd start out with 145 L, 150 R (Mikuni) mains. I'd replace the Chinese mains with true Mikunis for the 660 from a reputable dealer. Also replace the Chinese pilot jets with Raptor 22.5 Mikunis.

BTW if you instead use Dyno Jet mains the numbers are very different, so ask us.

Also, as t web said, make sure this is not a Reverse or Parking Brake limiter issue - read Raptor 660 Most Common Problems sticky at top of the 660 Maintenance section for detail.
 
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Discussion Starter · #6 ·
Welcome to the forum!

At 6000 feet you'll want 2 or 3 sizes smaller on your main jets. With your mods (at sea level) I'd recommend 155 in left and 160 in right carbs... but at 6000 I'd start out with 145 L, 150 R (Mikuni) mains. I'd replace the Chinese mains with true Mikunis for the 660 from a reputable dealer. Also replace the Chinese pilot jets with Raptor 22.5 Mikunis.

BTW if you instead use Dyno Jet mains the numbers are very different, so ask us.

Also, as t web said, make sure this is not a Reverse or Parking Brake limiter issue - read Raptor 660 Most Common Problems sticky at top of the 660 Maintenance section for detail.
Welcome to the forum!

At 6000 feet you'll want 2 or 3 sizes smaller on your main jets. With your mods (at sea level) I'd recommend 155 in left and 160 in right carbs... but at 6000 I'd start out with 145 L, 150 R (Mikuni) mains. I'd replace the Chinese mains with true Mikunis for the 660 from a reputable dealer. Also replace the Chinese pilot jets with Raptor 22.5 Mikunis.

BTW if you instead use Dyno Jet mains the numbers are very different, so ask us.

Also, as t web said, make sure this is not a Reverse or Parking Brake limiter issue - read Raptor 660 Most Common Problems sticky at top of the 660 Maintenance section for detail.
So I did the rev limiters with no change so I will be ordering the jets you recommended! I’ll get back to you once I get the time to tear into it and change the jets! Hopefully soon. Thank you for your help!
 
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