Locked300 honda, weird spark problem

Post
blue83ranger
Dirt Monster
2011/11/10 19:03:42
I bought another 300 (3rd one) a 1990 2 wheel drive and it needs alot a attention but seems like it will be somewhat nice when i'm done. First thing up is it has no spark, kinda. One of my other 300's is an '88 and it does run so i borrowed the cdi off it. and the '90 will temperarily have spark with it but only if i turn the handle bar switch on, turn the motor over, then turn that switch off and it will have great spark for about 3 revolutions then it will quite till i turn it on then off while spinning the motor over. It does not have spark, ever, with the switch on run or with the cdi that came with it. And i do have a repair manual and the stator tested good, battery is good, it's in neutral and the light comes on and i used an ohm meter on every wire going to the cdi and where the wire starts from and they all are good. Any ideas on this one? and thanks for any help.
BrendN KRA
Trail Rider
Re:300 honda, weird spark problem 2011/11/10 20:25:47
you could have a short, or something wrong with the handle bar switch.. maybe mud or somethings clogged in it making it not give power to the spark plug, id look at the switch and make sure theres nothing wrong there before moving on.
blue83ranger
Dirt Monster
Re:300 honda, weird spark problem 2011/11/10 21:01:25
I had it all apart and cleaned everything and regreased it. No change. One thing i thought was weird, i used a volt meter and one wire on the kill switch had 12 volts.
sierra53
Mud Master
Re:300 honda, weird spark problem 2011/11/11 07:33:47
It sounds exactly like the problem I had when I mismatched the Stator and Flywheel on a repair I did. Look to see if the left crankcase cover looks like it has been removed recently. The previous owner may have caused a problem by trying to troubleshoot another one. This may be why he ended up selling it. Good luck.
JPs300
Respected Member
Re:300 honda, weird spark problem 2011/11/11 09:35:25
an 88-91 CDI does not interchange with a 92+ CDI. - I believe this may be what is going on w/ pitbullmike007's 300, as it does not have spark while holding the crank button, but  starts instantly when you release the button.
Re:300 honda, weird spark problem 2011/11/11 10:48:14
a 88 cdi is all by its self. then its 91-93 ,94-97(i think migh be 98) then 99up. does it spark when you let off the start buttom? if so its the cdi
 
JPs300
Respected Member
Re:300 honda, weird spark problem 2011/11/11 13:01:47
^ there ya go. I couldn't remember the specifics, just that the early bikes were different than the later bikes.
 
Mike's will crank on the starter all day long if you hold the button, but fires right up & is ready to go the moment you let go of the button.
blue83ranger
Dirt Monster
Re:300 honda, weird spark problem 2011/11/11 13:11:42
The cover doesn't look like it was off in a very long time, if at all.
No, it doesn't start to spark when i let off the button. If i push the starter button, hold it in, then move the handle bar kill switch back and forth, off, run, off, run etc.. it'll spark when it's only off, but isn't continuous enough to run.
Re:300 honda, weird spark problem 2011/11/11 15:06:08
i would look into your switch. might need to be cleaned.
 
jp. thats just the cdi box making it do that. it might running for years like that or might go out today. mine did it for about a year and was doing it when i got the bike.
blue83ranger
Dirt Monster
Re:300 honda, weird spark problem 2011/11/13 18:09:35
I took the handle bar shut off switch apart and cleaned everything and it acts the same.
So, are '88 and '90's cdi different then? I've checked everything a few times and the cdi seems to be the only thing left.
Jake450s
Moderator
Re:300 honda, weird spark problem 2011/11/14 18:17:00
blue83ranger

...One thing i thought was weird, i used a volt meter and one wire on the kill switch had 12 volts.

 
That's perfect if the switch is off, ground side switches are going away...  Power is provided to the kill switch at all times when the ignition key is switched on.  The kill switch, when in the "ON" position will connect it's terminals and provide that twelve volts to the CDI, which will enable the coil control.  
Key on, Engine off, Kill switch off, you should see B+ on one wire, and B- (or a close approximation thereof) on the other.  That is valid for a volt meter only.  Depending on the CDI, some test lights can override that "turned off switch" and enable the CDI all by themselves.
Key on, Engine off, Kill switch on, you should see twelve volts on both wires, one side going in and one side going out of the kill switch.
 
Assuming that pans out...  If messing with the kill switch gets you spark (several, not just one single spark), then don't spend a whole lot of time on most of the system.  Investigate the CDI, the kill switch, and the wires in between those two items very carefully.  The remainder of the system (other sub systems within the CDI, the stator, flywheel, the coil, all their wiring...  You may or may not find some interrelation with the key switch there, but if the kill switch is recieving power, it's a straight shot from there to the CDI, and without the proper "enable" signal, it's not gonna run.
 
And yeah, CDI modules don't all interchange, gotta be real careful with swaptronics for that reason.  They kinda look the same on the outside, the plugs are the same size, but on something like that it's the part you can't see where all the magic happens.
blue83ranger
Dirt Monster
Re:300 honda, weird spark problem 2011/11/21 12:11:38
It runs! I ordered a new cdi, it got here saturday, i put it on and it had spark so I sprayed some carb cleaner in the carb and it fired right up and ran great, at least until the carb cleaner burned up. Now i have to clean out the carb and fix some other smaller stuff with it, and there will be another 300 brought back to life. thanks again for the help.