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Discussion Starter #1 (Edited)
Joined forum for current and future advice. Here's how goes. Brother bought his first bike. Its a 81 cx500. Off the bat we were told pitcock wasn't working and battery wouldn't charge. Ok fine, figured clean the pitcock filter, test the stator and regulator/rectifier. Upon checking pitcock discovered rusty tank and clogged pitcock. Between straw on pitcock and fuel filter I don't believe rust has passed to carbs. Regulator tested bad will be replaced stator tested good for the test. Could not do regular voltage check bc bike doesn't run yet. After hooking up battery charger and trying to start bike it won't fire. I'm getting great spark on both sides and even good compression on both sides. Just won't fire. I sprayed starting fluid into cylinders with no luck not even a backfire. Just spins and spins. It seems like the kill switch is on but its not. And it looks clean inside the electrical housing. My first concern is getting it to fire. I'm a decent bike mechanic in learning but this is beyond my expertise. Pulled carbs and they appear very clean inside and out though linkage was messed up. All help is apreciated. 13072879_980843125361965_1778622516090059383_o.jpg
 

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Download FSM, link below.
Follow procedures for testing stator and related components.

Pictures are a requirement on all build and repair threads, otherwise they are worthless!

Add your location to your profile, someone may be nearby to help.
Add bike details {year/model} to your sig so that we will not have to keep asking.
 

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Discussion Starter #3
Thank you for your contribution. Still new here learning my way around. I figured out how to add location and photo. The photo I have can not help with current situation. I currently do not know how to add a signature. I downloaded the FSM AND HAVE ORDERED A HAYNES MANUAL AS WELL.
 

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Welcome, you have good advice already. These bike come back to life nicely and are great machines to ride... good looking one ya got there...
 

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Discussion Starter #6
Thanks. I hope so. Hasn't had the most promising results yet but hopefully it will. Only get to work on it on weekends
 

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Discussion Starter #7
Worked on bike today. Found the main problem the spark plugs were completely wrong. Some idiot previous owner had lawnmower plugs in it! Got correct ngk plugs and some starter fluid and after a minute it fired up and ran. Now to do the adjustments to idle and either replace the pitcock with a non vaccum one or figure its set up out. But the goal was for it to fire so today was succesful. Back at it tmrw.
 

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Discussion Starter #8
So after today's work, the bike ran altogether for about an hour. It started and ran three times. Adjust the carbs until a nice smooth 1100rpms was achieved. The current issue is how hard it is to start. It seems to start simply when it wants too. Could the bad regulator cause this? Did the stator tests again and it's is working correctly. What other issues could it be? Carbs are set good. Strong spark on both sides. What am I missing?
 

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Discussion Starter #10
I don't clean them like that. If it comes to needing cleaned that thoroughly I'll just rebuild them. The carbs run great and I synced them with a vaccum gauge. It just seems to not fire. Or not time right if that makes sense. It won't even ignite the starter fluid usually. That's why I leaned toward the regulator possibly not getting strong enough spark??? You may be on to something as I don't know the history of this bike. But when I took them apart they were incredibly clean. Everything looked new. Even ran some seafoam through And compressed air.
 

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If you suspect a weak spark run through this. A bad 5/9 reading can give you starting issues.



You can also do a DC volts output test on the CDIs pink and yellow wires. You're looking for 100 volts +. Or the same test can be performed straight from the stators white wire {pin 9}
 

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Discussion Starter #13 (Edited)
I will try this as soon as I'm back over there. Thanks guys. I suspected the Cdi but not sure. If any of these test are bad do I need to replace the Cdi?
 

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Don, although you are a "bike mechanic".... you really should download a copy of the FSM and get a copy of Larry Cargill's Carb book.

Visual inspection of these carbs is not sufficient to determine clean. To use your words, you will likely have to "rebuild them".
 

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Discussion Starter #15
Thanks Knute. I don't mean bike mechanic as a licensed or practicing guy in a shop or anything just not a completely new to it. As for the carbs I don't believe they are an issue as of this moment. Once it fires it starts right up.
 

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in your diagnosis you dont actually say if you lose spark better check that next time it wont start

you have a vacuum petcock it may be sticking and not letting fuel thru

if you lose spark

the next time you have a no start unplug the black with white tracer wire that goes forward from the cdi box

this will put the cdi in run mode disconnected from the bike harness so you kill switch is disconnected as is the ignition switch

you will have to hook the wire up to stall the motor to shut it off but if the motor runs you know you have a wiring / kill switch issue not an ignition issue
 

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Discussion Starter #17
Thanks murrayf. How do I know if I lose spark? I always see it when I pull the plugs and ground them but I hear they may not spark inside but can be seen outside. How do I check this. Glad to see you guys are seeing this and responding. Much appreciated.
 

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Discussion Starter #19
I do have spark. Nice and blue clean plugs. New Ngk plugs. I'm going to bring the bike home tomorrow so I can do these tests and follow the advice more quickly.
 

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Discussion Starter #20 (Edited)
Ok here's the results from the stator ignition test
1-5 122
2-5 105
3-5 224
4-5 133
6-5 105
7-5 248
8-9 96
5-9 60

Also when I started it it started from a 50 amp jump. With kill switch unplugged
 
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