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Discussion Starter #1
Hi all, new member and recently acquired a 1989 cbr250R grey import. Only paid $700 for it and it has 6months rego. So we couldn't get it started the day I picked it up due to a dead battery so brought a new one. Then it would wind but was not sparking. So I pulled the number 1 plug out and reconnected it to the lead and head it just of the block hoping to see a spark. But no dice. So I then replaced the coils and leads just to be safe. Tried the same deal with holding the plug just off the block and still no dice. I then pulled the cover of the pulse generator and inspected it for any damage. It looked all good. But when I checked the CDI the small steel plate on the bottom of the unit has some oxidisation and rust on it. So my question is. Do I need a new CDI unit or should I go buy a volt meter and check the pulse generator? Any help or insight I would be grateful for.

Cheers tim_
 

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It's rare for the CDI to fail, but has been known to happen... I'd be checking EVERYTHING else first though! First thing I'd check is if there is a 'pulse' from the pulse generator. When I rebuilt my MC22, I forgot to plug it in (under the seat/tank) and couldn't figure out why the bike wasn't starting for days! The CDI is the most expensive part to replace, hence why I'd only do it as a last resort. A good little multimeter will only set you back $25, and if you're like me you'll find lots of uses for it! Other than that, I'd check the state of the plugs, little bit more expensive if you decide to replace all four, but worth it in my mind, especially if the motor isn't tuned properly, it'll foul plugs real quick. Good luck!
 

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Correct me if im wron guys but the cdi wont send spark if there is not enough battery voltage.
Op if you have a strong battery you can jump it off I'd suggest that.
 

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test light on the pulse generator signal wire i think it may show you if its working or not, have to back probe using a sewing pin
i've never tried myself but worth a go?
 

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The pulse is pretty quick, dunno if a test lamp will have time to light up, unless it's an LED type. Multimeter will however show voltage spiking up and down, even if it is delayed a bit. You could try it though...!
 

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Discussion Starter #7
I have a mate bringing his multi meters over on Friday/Saturday to test wtf is going on. I'm broke at the moment cause the new battery and the coils set me back $145. And I have some NGK plugs left over from when I used to have a mc22 years ago. So I will replace the plugs. Ok so it all comes down to the pulse generator. Thanks for all the input guys. No of the advice will be wasted.

Cheers tim_
 

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Discussion Starter #8
It's rare for the CDI to fail, but has been known to happen... I'd be checking EVERYTHING else first though! First thing I'd check is if there is a 'pulse' from the pulse generator. When I rebuilt my MC22, I forgot to plug it in (under the seat/tank) and couldn't figure out why the bike wasn't starting for days! The CDI is the most expensive part to replace, hence why I'd only do it as a last resort. A good little multimeter will only set you back $25, and if you're like me you'll find lots of uses for it! Other than that, I'd check the state of the plugs, little bit more expensive if you decide to replace all four, but worth it in my mind, especially if the motor isn't tuned properly, it'll foul plugs real quick. Good luck!
The bike has been sitting for a long time so in unsure as to its tuning state. But I don't intend on selling the bike so I don't mind spend the money on it to bring it up to schmick. It's for the mrs birthday and I know once she rides it she won't want to get off it. Hahaha
 

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multimeter won't be able to catch the voltage readings unless its got a small bar graph on it as well
shouldn't be using incandescent test lights in this day and age because LED test lights are so much safer to use and their not expensive
 

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Discussion Starter #10
Ok I will go check out a test lamp and see hat the guy at the shop says. I may just price a new pulse generator and install it. And I may just get a new CDI well I would price one any how. Never does hurt to have spares.
 

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Discussion Starter #11
test light on the pulse generator signal wire i think it may show you if its working or not, have to back probe using a sewing pin
i've never tried myself but worth a go?
Which wire is the signal wire?
 

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Check and clean all the connections under the tank before you start spending any more money.
 

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Discussion Starter #13
Check and clean all the connections under the tank before you start spending any more money.
Yeah I noticed there was a build up of crud on some connectors. What's the name of the spray you can buy that cleans them? Also thanks for the tip.
 

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I just used brake cleaner but you can get electrical contact cleaner which might work a bit better. Make sure you give them a bit of a scrub too if they look really dirty.
 

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Discussion Starter #16
Can someone explain to me how I should be using this multi meter. I asked a guy at a bike shop and I was told to "go to take get an apprenticeship spend 4 years learning to fix it then fix it, because I won't help you." And after having some words with him I was told to leave. So I'm still stuck. I went on YouTube and searched and only found single spark plug leads coils they were testing. And I tried it that way but it didn't work. I know this because I Drove to the wreckers where I got it from and I try my way of testing coils on a working coil pack and same result.
Cheers for any help
 

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Discussion Starter #20
Ok so I managed to stumble pain the right way of measuring the resistance of the coils. And I never need to replace them. So I now have a spare set. So then I moved to the pulse generator and here is what I got. Yellow/white-yellow 418 ohms. Blue/white-blue was reading nothing. So I have finally found out what has been wrong with this bike and making me pull my hair out. Thanks for everyone's help. And I'm sure I will have more.

Cheers
Tim_
 
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