95 SPX 657X. Low end bog PLZ HELP!!

[TurnerBFC]

Hey guys!

So I have this 95 SPX. 657x
I rebuilt these carbs with mikuni parts.
Stock jets.
0 turns on high speed
1.25 turns on low speed
New fuel lines cleaned selector valve. Have currently bypassed selector for elimination.
Pop off checks out at 30psi.

If I punch it out of the hole, it will bog right down for 5 seconds then slowly rev up and the top end is fine. It wakes up and rips on the top end just as it should.

Cannot wrap my head around it.

Any suggestions?

 

[warriorde52]

Did you check your pop off pressure?

Or think even simpler, how's the fuel filter look?

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[TurnerBFC]

Did you check your pop off pressure?

Or think even simpler, how's the fuel filter look?

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Fuel filter is brand new

 

[warriorde52]

Seems like a fuel delivery/metering problem.

Did you put new needle seats/valves in it? If you did how about the springs in the arm?

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[TurnerBFC]

Seems like a fuel delivery/metering problem.

Did you put new needle seats/valves in it? If you did how about the springs in the arm?

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Complete rebuild. All seems good.

 

[warriorde52]

Definitely check the pop off pressure. It could be higher than spec, causing it to lean out by not allowing your float bowl to refill. Similar to an accelerator pump not working.

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[warriorde52]

Nvm. Sorry I just read your post again and you did.

It could be possible there was something left in the fuel tank and got sucked up after the rebuild.

Was it doing this prior to the rebuild?.

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[Austrian Rotax]

have you checked the fuel baffle strainer? you might be surprised how plugged these could be, at least my fuel baffle strainer/filter was half plugged. Also turn out the LSA another quarter-half turn see if that helps and you will know if its running lean on the low end for some reason. plug colour after a WOT plug chop? when you just punch half throttle how does it act?