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banshee cdi help


hey guys long story short ive got a weird problem with my shee, after the full rebuild it seems i may have fried my cdi on the first start up im guessing because the voltage regulator wasn't fully torqued down and was arking sparks at night  :o  the bike just wont fire. i got nice blue spark on both side, fuel (carbs are good and clean) and tested 130psi comp on each side which is a tad low but should run just fine. flywheel key and all is fine ive tested all that.

so i had 2 buddys loan me there cdi boxes to try real quick over the weekend but both plugs are diff than mine? one was off a 2006 s/e and the other off  a old j-arm bike and the plugs were diff on both. they must have made 3 diff wire harness' over the years i guess. mine is a 2001 and i would like to try a working cdi to see if i fried mine.

does anyone know how to test a cdi to see if its shot?  electrical is not my thing lol

Re: banshee cdi help

Reply #1
hey guys long story short ive got a weird problem with my shee, after the full rebuild it seems i may have fried my cdi on the first start up im guessing because the voltage regulator wasn't fully torqued down and was arking sparks at night  :o  the bike just wont fire. i got nice blue spark on both side, fuel (carbs are good and clean) and tested 130psi comp on each side which is a tad low but should run just fine. flywheel key and all is fine ive tested all that.

so i had 2 buddys loan me there cdi boxes to try real quick over the weekend but both plugs are diff than mine? one was off a 2006 s/e and the other off  a old j-arm bike and the plugs were diff on both. they must have made 3 diff wire harness' over the years i guess. mine is a 2001 and i would like to try a working cdi to see if i fried mine.

does anyone know how to test a cdi to see if its shot?  electrical is not my thing lol

The service manual doesn't give a routine for checking the CDI boxes :( It says to eliminate all other possibilities and then assume that the CDI is bad.

You didn't say anything about sparks at night on the phone however, the voltage regulator and the ignition circuits shouldn't be intertwined like that. 
Click on the pic VVVV You know you want to....


Re: banshee cdi help

Reply #2

ok. the only thing that concerns me is the ground wire that bolts down to the one side of the volt reg. maybe it was coming in and out rattling then fried the box? thats the ground for the whole wire harness isnt it?

Re: banshee cdi help

Reply #3
ok. the only thing that concerns me is the ground wire that bolts down to the one side of the volt reg. maybe it was coming in and out rattling then fried the box? thats the ground for the whole wire harness isnt it?

I'd have to look back into the service manual to figure out for sure but MOST of the yammy products had two grounds, one at the front somewhere around the electronics and one at the coil base.  They were hooked together on most models.

I do see the concern about a ground issue frying the CDI though, sparks are never good (unless they're inside the cylinder)!
Click on the pic VVVV You know you want to....


Re: banshee cdi help

Reply #4
So this ran but now won't?
Lighting and ignition are  seperate coils on stator. Try running seperate ground from coil back to engine. This saves scraping paint/PC from frame on coil mount.

Re: banshee cdi help

Reply #5
Looking at this diagram that freek posted It's a 2001-
http://www.thequadconnection.com/yamaha/yamaha-banshee-wireing-diagram/

I only see Two ground points and that is the Voltage regulator and the coil itself.  I don't know if the Engine stop switch is grounded through the handle bars like the blaster is. I would assume so. I would suspect the source or pickup coils first, However you say you are getting good spark, I would still use a volt meter and check the ? on all the coils.  Source coil is 13.7-20.5?  and Pick up is 94-140?. If all those check good, I would swap out a CDI.


Re: banshee cdi help

Reply #7
well it was not the cdi and my wire harness checked out to be fine... waste of 100 bucks on the cdi lol

 thanks for that link Larry btw.

it has to be me carbs cause i put a tablespoon of fuel in each jug and she fired right up. So i ordered some new 28mm PWK's to just be done with it. i always loved that 33mm PWK carb on my blaster and never did me wrong not once. stock carbs are great but its hard to find an unmolested set nowadays, so these will be going back on ebay.

Re: banshee cdi help

Reply #8
Unmolested or worn out  >:( they could be up to 27 years usage

PWK have seperate air/idle screw , not with choke plunger, correct?

Re: banshee cdi help

Reply #9
The PWK are the carbs with the separate idle screw and choke knob.  The PJ's are the ones with them combined that give so much trouble.

After several calls about this particular problem, the decision is that it HAS to be something wrong with the carburetors.  The CDI was replaced, reeds checked, flywheel and stator checked.  It starts up with a manual primer of gasoline but bogs right off when that runs out. 
Click on the pic VVVV You know you want to....