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my jetting is bad, im lost

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i recently put in a high compression piston and ever since my bike has been very finicky about jetting. it was running rich afterwords, so i leaned the needle one position. now, when i rev it, the engine waits too long to return to idle.... but it doesnt "hang" after i rev it, just takes it sweet :thumbsup: time to get back to idle.

it also bogs when i land from jumps, but this only happens with a 2" endcap - it doesnt happen with a 1.75" endcap. what does that mean?

and why doesnt my engine go right back down to idle?

i dont know what to change or which way to go. :devil:

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Make sure the throttle cables have slack and are not pinched under the tank.

Adjust the idle mixture richer with the fuel screw. Turn it outwards 1/4 turn at a time to see if it helps. Go to a bigger pilot jet if you reach 3 turns out.

James

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Make sure the throttle cables have slack and are not pinched under the tank.

not a problem, plenty of slack.

Adjust the idle mixture richer with the fuel screw. Turn it outwards 1/4 turn at a time to see if it helps. Go to a bigger pilot jet if you reach 3 turns out.

James

but, this does not help. my fuel screw is between 1 3/4 and 2 full turns out, depending on the weather. it pops above and below that setting. the power doesnt get any better.

so that would point to a main jet/needle problem, correct? which way should i go, richer?

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The closed throttle idle will be unaffected by the main jet. You can remove the main jet and ride the bike to confirm (I did this and rode for 20 miles to see the results).

The closed throttle is affected by the pilot jet, fuel screw, needle diameter, and clip position. There are also air jets and cutaway, but they should not be a factor for you.

You have already tried a richer clip position, which would be the other chioce.

The slow return to idle is more likely a lean condition from idle circuit or cables slowing the slide return. Check for air leaks, check the cables, throttle stop, hot start, and float level.

The bog may be related, so focus on the low end problem first.

Hope this helps,

James

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well, i raised the needle one position thinking the mixture was lean. now, the bog is mostly gone and the slow return to idle is almost gone. but heres the wierd part...

it drastically changed the powerband. by changing the needle one position, my bike went from being a revver to a torquer. :cry: better power, but the bike no longer revs out and it prefers to be short shifted. even revving it on the stand, it doesnt seem to rev as high.

why is this happening? would raising the needle another position give me more power/torque? i feel like it could still use more fuel.

thanx james

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Ride the bike and see if it revs out hard. If it has problems revving and feels like it only is working in the low throttle range, try a smaller main jet.

James

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