cdi restriction

[houg]

on my 2002 cobra racer that i picked up not too long ago when i hit full throttle at top speed no load it will start spudering  like its running rich and loose rpms if i back off the throttle just a little bit the spudering goes away and the rpms come back up a little
 if im going up hill with the engine under load it doesnt spuder is this my cdi being restricted??
the color of the spark plug is a greyish it looks like its not running rich
HOW DO I DE RESTRICT MY CDI    CUT IT?

[Redk]

I have never 'cut' a cdi, so can't help with that.  It's seems a popular mod.

Sounds like your engine is 'four-stroking' at wot.
Main jet is too rich, causing it to overload with fuel and only fire every other stroke.

You will need to replace the main jet with a larger number, (probably +3 or +4 from what you presently have), which will be a smaller hole in the jet.

Of course, timing and condition of the air filter should be checked, first.
redk

[houg]

I have never 'cut' a cdi, so can't help with that.  It's seems a popular mod.

Sounds like your engine is 'four-stroking' at wot.
Main jet is too rich, causing it to overload with fuel and only fire every other stroke.

You will need to replace the main jet with a larger number, (probably +3 or +4 from what you presently have), which will be a smaller hole in the jet.

Of course, timing and condition of the air filter should be checked, first.
redk

no     my cdi was restricted i unpluged the green wire loopimg in and out of it and its running 100% better at WOT
and i think you have it wrong the larger the number on the jet the bigger the main jet,   now if your drilling them with a numbered drill bit set then the smaller the number the larger the hole
http://www.affordablegokarts.com/Drilling%20Main%20Jets.php

[Redk]

houg, you are correct, and I am wrong. Again.  :-)
Sry, I have never bought a jet in my life...  always filled and drilled.
I have purchased needles, though, for Mikuni carbs.
redk

[Elrodpetit]

How much size should I use to fix it?