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  #1  
Old 01-22-2014, 02:03 PM
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Default 87 yz250 issues

Ok, so I have a 87 yz250. I bought it not running and got it running today. It seems like the spark is Inconsistent when you kick it over.you have to slowly kick it over and it feels like it hits a compression stroke, kick it a little more an it feels like another lower compression stroke, kick it hard and it sparks once. If I have gas, it will start and run, but I would think it should spark more than that? And you have to kick it this way or it won't spark at all!

Maybe this is just because I'm used to four strokes.


Another question, the kill button does not work, I went thru the whole wiring harness and it appears to be in good shape. I replaced the switch with another kill switch, no matter if the button is depressed or not it sparks either way. There is the black wire going to the coil, and then another wire goes to the CDI box, What else could it be?

Is it possible that the wire on the coil from the switch is on the wrong side? I believe its on the secondary side. I don't have a wiring diagram.

Last edited by Archerman0531; 01-22-2014 at 02:09 PM.
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Old 01-22-2014, 03:15 PM
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Ok, check your coil mounts for dirt or rust. Then check the plug cap to be sure it's clean. Then do an ohms test on the primary and secondary sides of the coil.

Paw Paw
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Old 01-22-2014, 03:31 PM
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[QUOTE=PawPaw;706234]Ok, check your coil mounts for dirt or rust. Then check the plug cap to be sure it's clean. Then do an ohms test on the primary and secondary sides of the coil.

Paw Paw[/QUOTE



Took the coil off and took emery paper to the mounting tabs and where it mounts to the frame.
The plug cap is clean, I have an inline spark tester as well to check for spark.

I don't have a service manual to get the specs for the coil, stator, or cdi.
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Old 01-22-2014, 06:18 PM
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Default ????

You will need a service manual to do testing.

Paw Paw
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Old 01-22-2014, 06:29 PM
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I know I need a service manual for that info. I don plan on keeping the bike. So, I doubt I'll buy one. It runs fine if you kick it over right the first time. I've had 2 of those and both of those dint have to be kicked over like I said in the first thread. I took the stator off and cleaned all the surfaces of it, cleaned the pick up, went thru the whole wiring harness.
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Old 01-22-2014, 07:49 PM
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OK, so in other words you want some free help to increase your profit margin and not for you own use. If you have the manual when you sell the bike it should create extra income for the bike when you sell it. If you are running a business, then treat as a business and invest in it.

Paw Paw
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Old 01-22-2014, 08:26 PM
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Not a business, Just doing this on the side because I like this.... I've never seen this before. I've had many dirtbikes, ATC's, and atvs. But I do fourstrokes, I'm not to familiar with two stroke. maybe it sparks only once, idk. That's why I was asking.

I was more concerned with why the kill switch didn't work.
Who knows.
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Old 01-23-2014, 10:22 AM
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OK, again ........you need the manual for your testing! End of story! Hint....your bike should create a spark on every revolution.

Paw Paw
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Old 01-23-2014, 11:04 AM
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oh we got into kill buttons awhile back. very mysterious sometimes. I think yours is probably not getting a good contact to the stator wire/connection though. funny how we are expecting them to provide a good ground through handle bars that are sometimes mounted on rubber, and the final path to the frame is via roller or ball bearings that are in grease. What could go wrong there?
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Old 01-23-2014, 12:17 PM
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Pawpaw-
When I asked my first question, I wasn't looking for someone to give me the answers to everything. I was just curious as to if how I explained the bike needed to be kicked over to start was typical of a two stroke bike or not. No where did I ask for resistance specs and how to check the electrical circuits. I know how to, but was just wondering if what I said is typical for a two stroke bike, because that I don't know. It does have spark at every revolution when it's running, but you can't just jump on and start kicking away unless you set it up like I previously said.




Quote:
Originally Posted by ossagp View Post
oh we got into kill buttons awhile back. very mysterious sometimes. I think yours is probably not getting a good contact to the stator wire/connection though. funny how we are expecting them to provide a good ground through handle bars that are sometimes mounted on rubber, and the final path to the frame is via roller or ball bearings that are in grease. What could go wrong there?

I tried searching on here for some answers on the kill switch theory and how it works, I only found 1 post and then I had to go back to work.
I know one wire goes to the coil and the other wire goes to the CDI box, I wasn't or sure if the CDI box was internally ground or if the CDI box has a ground wire, Haven't looked into it to much yet.
Thanks for a place to check tho, I will take all connections apart and clean them.
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Old 01-23-2014, 12:31 PM
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what you really are trying to ground is the power coming over from the stator. I havent seen what the factory does with that one
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Old 01-23-2014, 12:45 PM
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Quote:
Originally Posted by ossagp View Post
what you really are trying to ground is the power coming over from the stator. I havent seen what the factory does with that one
So they're jut not energizing the coil when the switch is pressed....from looking at how the switch was wired I thought maybe they were making a less resistance path thru the switch and that keeps the spark from getting to the plug.
But what you say makes more since to me.
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Old 01-29-2014, 03:38 PM
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Got the kill switch fixed today. I still can't figure out the reason why you have to kick it over like I described in my first post. I rode it around today and it runs great and idles great, but it won't spark all the time when first trying to kick it over if you don't set up up right.
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Old 01-29-2014, 04:42 PM
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Wire one to the hot side if the secondary coil and your arm about flies off the bone at your elbow

Last edited by ossagp; 01-29-2014 at 09:07 PM.
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Old 01-29-2014, 07:52 PM
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I've got an inline spark tester on it, I don't need to shock the crap out of myself again, Did it once, never ever doing it again.



I had an 86 yz250 last summer and it seemed like it had great spark and would spark no matter where the piston was when you would start kicking it over....maybe I'm remembering wrong.

There is no adjustment on the pulse pickup, is it possible that my rotors magnet is worn down to much and not being able to get a good connection as it passes under the switch? But if that were the case I would think it would run like crap, esp at higher RPMs. But it runs great when it's running.
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