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Discussion Starter · #1 ·
Have a 1980 GS450l then ive been riding daily for about the past month now. On my way to work however a few days ago I was riding in 3rd at maybe just around 3k when the light turned yellow and I opened it to full throttle without downshifting. It accelerated fine through the intersection but seemed to bog down then backfire when I started letting off on the other side, it then died and I coasted it into a parking lot. As of today heres what I know: engine cranks over perfectly fine, engine is getting fuel, engine is not getting spark (removed and grounded plugs, nothing), got new spark plugs because the old ones looked nasty af (STILL NOTHING) however when I took a multimeter to the spark plug wires they were receiving voltage so im not sure whats going on. thoughts?? thankyou
 

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.... It accelerated fine through the intersection but seemed to bog down then backfire when I started letting off on the other side, it then died and I coasted it into a parking lot.
Sounds like reason enough to look an see if the carburetor slides returned to their normal idle position, or is one stuck at wide open throttle?

... ;) and of course you do realize you are suppose to proceed with caution and not accelerate through a caution light.

On the no spark observation, is highly unlikely both plugs packed it in at the same time, not sure where you are getting a meter reading for the spark plug and there are too many possibilities to guess without more trouble-shooting. Make sure it's not something silly like a side stand cutout switch first.
 

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Discussion Starter · #3 ·
... ;) and of course you do realize you are suppose to proceed with caution and not accelerate through a caution light.


Pschhhhhhhht what?

Definitely will check the carbs next, im pretty sure im getting fuel, the smell is pretty obvious. But maybe im not get enough air in the cylinder.
I tried testing the current just by putting my positive lead on the spark plug wire and grounding the negative, was getting around 11ish volts when the ignition was on and it would drop to maybe 6 when cranking
 

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Sounds like you are actually getting a voltage reading off the battery.
Voltage coming out of the coil and going to the spark plug is huge voltage.

Pretty sure your bike has CV carbs, one butterfly valve followed by the slide throttle which is lifted by vacuum off the intake, that is the one I was thinking Might be stuck open.
 

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Discussion Starter · #5 · (Edited)
Alright cool ill give the carbs a check in a few hours. If the slide valve is stuck open is it just dumping fuel in there basically then?

sooooo heres what we got:
Checked the carbs, they look good, im getting fuel and air and both the butterfly and slide valve look to be functioning properly. so im about %99 sure its electrical now. I did some more reading of the spark plug wires and heres what I got:

Left Side of engine (sitting on bike):LS
Right Side of engine:RS
key off & engine switch off- LS: 0 volts RS: 0 volts - looks good
key on & engine switch off- LS: 0 volts RS: 0 volts - also good
key on & engine switch on- LS: 11.7 volts RS: 1.7 volts - what the f#ck...
key on engine switch on & cranking- LS: 8.4 volts RS: 2.4 volts - huh..
Battery btw roughly 12.4 volts

Tested cranking with the plugs pulled out and grounded, both with the old plugs and the new ones in case that was somehow the problem, no spark. Could this be a short somewhere in the system? weird this would just happen running a light...
all helps appreciated help me get this running!!
 

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I'm finding conflicting wiring diagram information for your bike! but I do see what appears to be an inline fuse, make sure that is good. I would normally meter test starting at the stator coils first because it's not hard to do and that is where power generation begins, the process will be outlined in the bikes service manual. Most likely 3 wires coming from the engine (often yellow in colour) and each should output the same or similar voltage when you turn the engine over.

Does your bike have breaker points ignition or a CDI type ignition? Post a link to the correct wiring diagram if you have one.
If you have points then the points and condenser is the next place to look, if it's solid state troubleshooting gets a little more complicated unless you have access to replacement parts.

... I'm also trying to relate the problem to the acceleration, but if it is an electrical short in say a stator coil winding, the timing of that failure would be purely coincidental.
 

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Discussion Starter · #7 ·
I know that stator is working, installed a new one maybe 2-3 weeks back because my old one wasnt generating enough power to recharge the battery. I also know I have CDI ignition if that helps.
 

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Normal is a 3 phase alternator (3 coils) to generate ~ 20 some odd volts to the voltage regulator and rectifier,
CDI means you have an additional pickup or field coil in there to provide spark instead of breaker points,
.. some bikes are totally dependant on having a 100% good battery in place, others tolerate no battery or faulty battery, difference usually being if it has a battery/coil ignition.

You probably need to test the alternator windings again, you might be burning out coils for a reason somewhere else in the system.

Troubleshooting the rest of the CDI is easiest done by swapping out entire assemblies with known good parts
;) is much easier if you have 2 of the same model bikes.
 

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That bike should have a double pickup under the "points" cover, so start by checking resistance of both of them. They had a reputation of killing the CDI unit too and they used to be quite expensive but I think there are cheaper replacements on the market now out of Europe.

You could also look at replacing the CDI and pickups with a simple Dyna system if yours has the mechanical advance. If it's the later version with electronic advance, you may be easier to try to locate a replacement CDI - if that is the problem.

But start with wiring and trace it from ignition switch to pickups and coils and look for chaffed wires and rusty connections.
 
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