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-   -   1200s mid throttle stumble (http://xlforum.net/forums/showthread.php?t=2071454)

NZstu 18th October 2018 02:16

1200s mid throttle stumble
 
Hi experts.
I have a small carb stumble that im struggling to eliminate.
I have read countless tuning posts but its still just a little annoyance.

I have a 1200S with a fully flowing k and n filter and debaffled mufflers and have also pulled the balance pipe to access the carb easily

I have just had the head and inlet gaskets replaced and have changed pilot jet to a 45

I have also removed the washer that was under my needle as it made it a lot better.

I guessed i was over fueling and fouling plugs....




My needle is at around 2 and a quarter out

Right so the issue i cant figure out is my bike is running great generally but when i am riding downhill or if i crack the throttle open i am getting a hesitation/bog when im at mid throttle.
I have tried the standard tuning methods
Idle drop but its not being very obvious when the revs drop.
I thought i had it dialled and it was great until i did a slow coast diwn a long winding hill behind a large truck.

Next time I leaned it out till popping on decel and then wound out another 1/4 until it stopped and i occasionally still get the cough..
So i am very close but i feel i am missing something?

I welcome your comments

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sportsterdoc 18th October 2018 03:06

A 45 pilot, with an unshimmed N65C needle and mixture at 2 1/2 (perhaps up to 2 3/4) should be good.
Before any other adjustments, check for a vacuum leak, even with new gaskets.
An unlit propane torch may help.

NZstu 18th October 2018 03:17

Hey thanks for that..
How exactly do i verify the needle?
Its a stock one I believe???
I presume the S model has a different.
Im sure i read that somewhere

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IXL2Relax 18th October 2018 05:17

Here's the Sportsterpedia section on CV40 Carbs with internal jets & needle listed:
http://sportsterpedia.com/doku.php/t...ter_model_year

Be sure to select the correct listing - USA 49-States (Dom), California (CA) or International (HDI)

Does your needle have a stamped number on the shaft?

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NZstu 18th October 2018 05:34

N86k needle as mine is a 99 Japanese spec

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sportsterdoc 18th October 2018 06:22

You may find this helpful

https://cv-performance.com/harley-cv...-tuning-issues

and this
\http://xlforum.net/forums/showthread.php?t=165259

Also RocketmanGB has a needle chart

Does the accelerator pump squirt strong?

NZstu 18th October 2018 20:40

Yup the accelerator pump delivers a solid squirt directly at the needle area

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sportsterdoc 18th October 2018 22:54

Quote:

Originally Posted by NZstu (Post 5708051)
Yup the accelerator pump delivers a solid squirt directly at the needle area

Slide diaphragm checked or slide travel checked?

NZstu 19th October 2018 00:12

All seem ok..
Will look for intake leak tonight

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bustert 19th October 2018 04:41

how strong is the accel jet? is it constant? is it timed right?
the way they supply fuel to it sucks, not like days of old. you have no control other than timing it and any thing inside the gallery feeding the circuit will screw it up.
when i changed exh, i had to open the port on the spray head a tad.


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