Diagnosing bogging

Mx391
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Mx391
Picked up a 04 rm250 with a leaking crank seal. Replaced seal, installed in top end and now bogs like crazy (bogged before also). Got a 165 main jet, 7 slide, needle in 3rd position. I cant get bogging to go away. Any suggestions? Maybe a powervalve issue?
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digger
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digger 1/24/2018 9:00am
1/24/2018 9:00am
What you are describing is a lean condition. What are the other jets in the carb ?

If you know the bike is mechanically sound, and with no air leaks. The jetting for that bike should be right around an NECW needle in the #3 clip, a 45/48, air screw dependent, pilot and a 168 main. Set the air screw at 1.5 turns to start out, and make sure the float level is set to 8mm. These setting will get the bike in the ball park without a bog. It will give you a place to tune from. If you still have a bog after those setting, you may very well have a mechanical issue else where
Acidreamer
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Acidreamer 1/24/2018 9:02am
1/24/2018 9:02am
Did you replace both crank seals or just one? If you only did one theres a 50% chance you picked the wrong one
Mx391
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Mx391 1/24/2018 2:07pm
1/24/2018 2:07pm
speed_racer wrote:
Broken Reed?
Brand new vforce 3 reeds. Forgot to put that in the original post.

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Mx391
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Mx391 1/24/2018 2:08pm
1/24/2018 2:08pm
digger wrote:
What you are describing is a lean condition. What are the other jets in the carb ? If you know the bike is mechanically sound, and...
What you are describing is a lean condition. What are the other jets in the carb ?

If you know the bike is mechanically sound, and with no air leaks. The jetting for that bike should be right around an NECW needle in the #3 clip, a 45/48, air screw dependent, pilot and a 168 main. Set the air screw at 1.5 turns to start out, and make sure the float level is set to 8mm. These setting will get the bike in the ball park without a bog. It will give you a place to tune from. If you still have a bog after those setting, you may very well have a mechanical issue else where
I am not positive that the rest of the bike is mechanically sound. Which one is the air screw? Top or bottom one?
Mx391
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Mx391 1/24/2018 2:09pm
1/24/2018 2:09pm
Acidreamer wrote:
Did you replace both crank seals or just one? If you only did one theres a 50% chance you picked the wrong one
I only replaced the clutch side crank seal. It no longer blows gear oil out of the pipe now....so I assume I picked the right one.
Mx391
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Mx391 1/24/2018 2:14pm
1/24/2018 2:14pm
Forgot to add that it will start and idle great. When you start to give it throttle, it will bog.
FGR01
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FGR01 1/24/2018 4:55pm
1/24/2018 4:55pm
Sounds like an air leak somewhere. I'd start by spraying around everything with starting fluid.

I'd also seal up that V-Force reed block with a nice, thin coat of moto-seal or some other gas-proof sealant. I've had trouble with those leaking before.
Mx391
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Mx391 1/24/2018 8:03pm
1/24/2018 8:03pm
FGR01 wrote:
Sounds like an air leak somewhere. I'd start by spraying around everything with starting fluid. I'd also seal up that V-Force reed block with a nice...
Sounds like an air leak somewhere. I'd start by spraying around everything with starting fluid.

I'd also seal up that V-Force reed block with a nice, thin coat of moto-seal or some other gas-proof sealant. I've had trouble with those leaking before.
Ill give that a shot

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