1989 yz125 weak spark. Help !

[Psygn0sis]

Hi everyone,

I'm new here and to my yz. I just got my first bike about a week ago for free. The previous owner *my brother* just didnt have the time repair it.

So I get her home and find out that it has no spark... so I pulled the plug and held it in my hand against the frame and can feel a shock, but again no spark.
So I bought a working used coil off egay and a new throttle cable and spark plug from my local yamaha shop; installed it all... closed the spark plug gap a bit more. After kicking it for a few she came to life then died... started right back up in one kick... then she died about a min later because i forgot to open the petcock. I opened it up and she hasent started sense.

My fear is that the CDI needs replacing because of the weak spark. Is there a way I can test the CDI at home ?

Or are there any *cheap* ideas you guys have.

 

[Andy428]

spark

Stator

 

[Psygn0sis]

You really.. wholeheartedly believe it's just the stator?

I can only afford one part...

CDI
or
Stator

 

[Psygn0sis]

please.... anyone...

 

[whenfoxforks-ruled]

You need the specs on your electrics, you need a multitester and check. Without this all you can do is visual inspection, check all the connections, check that everything is tight, dry, no signs of corrosion.

 

[dirty10]

First, turn the petcock to off and drain the carb. Leave the petcock off and kick it a few times. See if she fires at all. If it fires then your float is most likely NOT working properly. Take the carb out and clean it good. Make sure the float valve is working right.

How long was it sitting? I bet the carb is gunked up and when you turned the gas on, it flooded.

 

[76GMC1500]

I had a CDI go bad once. The bike still ran, the timing was just way too advanced at idle and it misfired at idle (this was a 4-stroke). Everywhere else, the bike ran fine. I realized it was the CDI that was bad when I (I'm still not sure why) squeezed the CDI box while the bike was running. The misfire went away and the bike started running great until I let go of the box. I taped it up real good and managed to get a few more rides out of it. Then, on e8ay, an entire wire harness for the bike popped up. Talk about luck, I doubt I'll ever see another CDI box fora 1986 TT225.

Do you have any hills near by you can use to push start the bike? You might also be able to test the stator using a multimeter if you can find the appropriate specifications in a service manual.

 

[Psygn0sis]

I already took the carb off and cleaned it out the best I could. But I will try turning the petcock off trick.
But what would the carb have anything to do with no spark ?

The only manual I can find on a 1989 yz125 is on egay... its all ripped up and held together with a paper clip and is going for $25.00 !!yikes!!

Does anyone else have a 1989 yz125 manual that can give me the appropriate specifications on the coil,stator and how tot test the cdi ?

 

[76GMC1500]

Yamaha sells the manuals through the dealer, they're about $65.

 

[WaldoVH]

I bought a good used coil off that online auction site once... it was probably a good coil but wasn't for my bike even thought the seller said it was.

Motorcycle coils I'm finding are kind of finicky beasts, You need to get a multimeter and check it. (the specs are in the book)

You don't need to buy a factory service mannual to check your CDI. The $30 aftermarket books give all the specs. Owning a book for a 15+ year old bike is critical.

 

[Psygn0sis]

well in my rush to hop on this thing I bought a new stator off of egay.
But the maunual is next on my list.

-keep you updated

 

[WaldoVH]

Don't do what I did!

I had a bad coil and replaced it with my online auction coil then started buying other parts when it still didn't run. Stator, ignitor, CDI and finally a manual. I spent $400 and had my new bike sitting for two months because I threw parts at it instead of diagnosing it properly.

 

[Psygn0sis]

UPDATE:
I pulled the stator today and upon visual inspection I see bare wire leads and insulation melted to the plate. I put a multimeter to it and the resistance is way too low. :)
That's a good thing...
That would account for my shock.. but no spark !

-will update when the new stator arrives.

 

[Psygn0sis]

The stator from egay arrived today.. installed it in just mins... now shes starts up one kick !! And shes running balls to the walls !!!

It was the stator all along.
Thanks dirtrider.net community ! :cool:

 

[dirty10]

Congrats! Good work.