re-jet with CDI
#11
#13
re-jet with CDI
No, CDI's shouldn't effect jetting much. Jet size is more a function of how much air the motor can pump on one cycle. That's why the airbox and exhaust mods require jetting. Those mods directly effect airflow.
HOWEVER a CDI can reveal a mixture problem that was there to begin with. If you are running a tad lean with a stock set up and then change to a CDI that advances the timing curve you may experience detonation sooner. The lean condition may have been there all the time but never caused much trouble due to the mild timing curve. Also, many here have testified that the low end miss on the BF750 is due to a lean condition and gets worse with a Dyna CDI. In that case the problem was there all the time and gets magnified by the more aggressive timing curve.
Whenever you move toward higher performance you also move toward a more finicky motor. That is not to say high performance is a bad thing [img]i/expressions/face-icon-small-smile.gif[/img] but is is to say that along with the intended mod usually comes some tuning. A decent tuner can get a little more punch out of a motor and still get reliable operation as well. Few mods are true "bolt ons".
Sometimes when I give my 2 cents, folks will hand back change [img]i/expressions/face-icon-small-smile.gif[/img]
God bless,
-BunnMan
HOWEVER a CDI can reveal a mixture problem that was there to begin with. If you are running a tad lean with a stock set up and then change to a CDI that advances the timing curve you may experience detonation sooner. The lean condition may have been there all the time but never caused much trouble due to the mild timing curve. Also, many here have testified that the low end miss on the BF750 is due to a lean condition and gets worse with a Dyna CDI. In that case the problem was there all the time and gets magnified by the more aggressive timing curve.
Whenever you move toward higher performance you also move toward a more finicky motor. That is not to say high performance is a bad thing [img]i/expressions/face-icon-small-smile.gif[/img] but is is to say that along with the intended mod usually comes some tuning. A decent tuner can get a little more punch out of a motor and still get reliable operation as well. Few mods are true "bolt ons".
Sometimes when I give my 2 cents, folks will hand back change [img]i/expressions/face-icon-small-smile.gif[/img]
God bless,
-BunnMan
#14
re-jet with CDI
Bunnman Great explamation and tact to (something Im always told I lack) it,s all in the tuning. Mods dont mean anything if your quad does not run right. How do you think I win all the events I do on a 650 TUNING . (and a few more mods than I have listed)[img]i/expressions/face-icon-small-smile.gif[/img]
#16
re-jet with CDI
I didn't rejet at first, but when I later had a chance to test my STP700 with a stock STP700 I discovered I had actualy lost a little. On the dyno it was showing to be safe but we have found this motor likes to be almost rich for optimal performance. I would say if the CDI is all you did you are ok. I have a Procircut exhaust, dyna CDI, and K&N filter. Its when you start combining mods that it starts to get to lean to perform. its been rejeted now useing the dyno and ehaust sensors. to give you an example at the rear wheels stock is 30 to 32 hp mine with all the mods was only 30 hp befor the rejet after rejeting for the mods we got it up to 37.5 hp. so to answer you question you do not have to rejet but to get your optimum gain you may want to especialy if you have other mods.
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