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The bike spits and sputters with any throttle while in gear, usually starts and idles fine. If it sat for a minute or 2, i can rev it up in neutral, until i put it in gear and get halfway up my short driveway.

I bought a 93 vlx 600 about a month ago and it was running great for 1000 miles. 2 weeks ago, it wouldn't idle. One of the spark plug boots had separated from the wire. With a field expedient fix, we were able to continue the ride, another 100 or so miles of smooth operation. I then ordered some new wires, 100 bucks for the set. And ordered new plugs, so i changed everything. The first attempt, i was a bit lazy and didn't take off the gas tank, just picked it up a bit and reached underneath. that was a bad idea. I didn't get the pug wires inserted enough and after reassembly, had no spark to the front pugs. i went and bought a siphon hose and drained the tank, removed it, trimmed a bit off the plug wires and reinstalled.

For my test ride, at night, it ran fine for a half mile to the cul-de-sac. after turning around and getting on it, The engine started cutting out with throttle. As it cut out, all the light would shut down, then brighten back up when i released the throttle and she would idle normally. I went down the road another mile or so then turned around. All with the same issue. When i got back in my driveway and shut her down, it would not start back up. a day or so of troubleshooting, i ordered an ICM. When i installed the icm, the engine started right up. i reinstalled the old one and the engine started right up. i reinstalled the new one, fired up the engine put it in gear and off i went. About 20 feet. Spitting and sputtering.

i didn't have spark to any cylinder. now i do. I've played with all the wires and cleaned connections, metered pretty much everything in the service manual. This is my girlfriend's bike that i bought her for christmas and it's driving me insane. The gas should be fine, I filled my '13 triumph from the same nozzle, and it's had no issue. i'm reading 12.7 v from the battery, i've had it sputtering with the charger connected.
 

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between that fact and my Aviation electrician background, i think i got stuck on the electrical side of things. pulled the brand new plugs today and they were white. reinstalled the old plugs(that were a bit more black than they should be), no change. I'm now thinking that I did something weird with the twisting and turning of the gas tank. i have a clear filter that was looked fine. i did buy a new filter that i will install tomorrow with some brand new gas.
 

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Have you checked the stator and regulator/rectifier output as well as the "three yellow wire" plug? I have a 1994 VLX and was having similar symptoms. Turns out the R/R was shot and the three yellow wires were fried. When you give it throttle and the ignition system starts drawing power, the battery might not be keeping up with demand (hence the dimming headlight). Check the three yellow wires first (the plug between the stator and R/R first. May need to be cleaned of plug cut out and wires soldered. Several videos on Youtube showing how to test stator output and R/R. Can't hurt to at least test them before buying any more parts.
 

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Discussion Starter #6
Have you checked the stator and regulator/rectifier output as well as the "three yellow wire" plug? I have a 1994 VLX and was having similar symptoms. Turns out the R/R was shot and the three yellow wires were fried. When you give it throttle and the ignition system starts drawing power, the battery might not be keeping up with demand (hence the dimming headlight). Check the three yellow wires first (the plug between the stator and R/R first. May need to be cleaned of plug cut out and wires soldered. Several videos on Youtube showing how to test stator output and R/R. Can't hurt to at least test them before buying any more parts.
I have not checked the stator and R/R yet. I'm going to do some fuel checks first. I'm beginning to think i knocked something loose when i was yanking the tank off, and clogged the fuel system. hence the white spark plugs. it's currently quite torrential outside and i don't want to open my garage door.
 

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You don't mention any history on the bike. Was it in extended storage before you bought it? Not that you may not have an electrical problem, but I'd be looking at fuel delivery. If the plugs are white, they are way lean. If they weren't firing properly, they'd be wet and dark. Get yourself some seafoam and run it through. You may just have dirty carbs. I'd also open up the a/f screws a bit temporarily to give it more fuel. You can always close them down a bit later if needed after running the seafoam through it.
 

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Discussion Starter #9
You don't mention any history on the bike. Was it in extended storage before you bought it? Not that you may not have an electrical problem, but I'd be looking at fuel delivery. If the plugs are white, they are way lean. If they weren't firing properly, they'd be wet and dark. Get yourself some seafoam and run it through. You may just have dirty carbs. I'd also open up the a/f screws a bit temporarily to give it more fuel. You can always close them down a bit later if needed after running the seafoam through it.
i don't have much in the way of a history on the bike. It's 22 years old with 23k miles, so it sat up at some point. It had been running smooth for 1000 miles before it instantly turned to crap, a bit rich, but not too bad. The old plugs were blackish and dry. I've been using startron with every fill up. A friend suggested some crap got past the filter and stuck in the carb. The carbs could use a cleaning, but i wanted to get it running properly before i take them apart. If i do something improper during reassembly, i want my problems isolated. One of the things i have done is reinstall the old plugs. No effect. I know the fuel pump runs, now i need to check the flow rate.
@jstulman, i've had the same issue with the tank on or off, with the hoses in full view. Also, i have run it with the tank open, so it's not a vent issue. I had run it dry with the tank off, when i reinstalled the tank it seemed like it took a long time for fuel to flood the filter (clear filter). I have blown through the petcock, that worked properly in all positions. The hoses are not collapsing or kinked.
 

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Put a meter across the battery and run it and rev it up to see if it can put out up to 14.5 volts or drops down. If the ignition is starved for power it can feel just like it is running out of gas.
It doesn't have aftermarket air intake and filters does it?
Even running with the air box disconnected from the carbs causes some bad running on a lot of these bikes.
 

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Discussion Starter #11 (Edited)
Put a meter across the battery and run it and rev it up to see if it can put out up to 14.5 volts or drops down. If the ignition is starved for power it can feel just like it is running out of gas.
It doesn't have aftermarket air intake and filters does it?
Even running with the air box disconnected from the carbs causes some bad running on a lot of these bikes.
i'm getting 12.7 on the battery with the engine revving, 12.3 engine off. I've taken the air filter off , no change. the airbox is connected.
I guess i'm fixated on stuff i messed with right before the problem started (plugs/wires/ shaking/removing gas tank). I only went a half a mile and turned around, the issues started instantly.
The fuel filter and pump flow fine.
I know the battery has a sticker from 4 or so years ago.
 

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If you never get it to increase over 13.5 volts the charging system is not working properly. It should go up to about 14.5 volts revving normally. If the symptom shows up just sitting still in neutral and revving you could put a car battery across it to see if a stronger power source will stop the problem.
Possibly when you were working on the coils and wires you moved the primary terminals on the coils and now they are loose and allow vibration to cause intermittent connections. That on and off spark situation makes me think it is loose connectors for the ignition.
 

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Discussion Starter #13
installed a new stator and voltage regulator and battery, no change
i've checked all the coi connections. clean and tight.
it idles fine, doesn't rev worth a crap. won't idle with the clutch out. (i put a velcro strap around the clutch lever while i'm starting the bike alot, remove it when i want a test drive. then it runs like garbage.)
even with the clutch in i don't think it's revving past 2k or so. just loud enough that my neighbors most likely are running out of patience.
 

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Discussion Starter #17
except for the carb, i've disassembled and tested all of that. blown through hoses and checked routing, tested the relay, the pump has looks to have a good flow rate.
Taking the carbs off and cleaning them out is my next step.
 

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Discussion Starter #19
took the carbs off a cleaned them up, had fully clogged jets. During the removal process, i found a dangling wire tucked under some stuff. It's the ground for the front coil. Now the bike runs like a champ. Thank you all.
 
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