Backfiring won't rev

[Gateway]

I have a 1980 GS 550E. It sat for many years. I did the " 20 years worth of maintenance " on it .... rebuilt carbs, rebuilt brakes, wheel bearings, valve adjustment, all new clutch plates and a seemingly endless list!! The bike ran fine for about 500 miles. Tonight I drove about a mile and it started having a slight cough and hiccup. I checked the fuel. Valve on, plenty of juice in the tank. Then all of a sudden the hiccup-cough turned into .. It won't rev and backfires, but idles fine. I sent my son back to fetch the van and I took it home. I pulled the plugs and they looked fine. I checked for spark and there appeared to be none... then there was, wasn't, was , wasn't. Then there was and it stayed, but still backfired and won't rev. Any clue were to start!! I am a vintage dirt bike guy, this is my 1st vintage street bike so, ... where to begin??

[chef1366]

Either your petcock is bad or you have a rusty fuel tank.
Check the battery also.

[chuck hahn]

The issue doesnt seem to be fuel to me..SEEING THAT you have sopark...then no soark..then spark..then......


Take off the tank and clean and check all the connectors under there. Pay close attention to the 6 pin white one...is it melted?

Also check the connections in the headlight bucket. the kill switch, ignition, etc etc all plug in inside there.

Youve got to check all the connectors AND the grounds fron the wiring harness to where they bolt to the frame..,.also the timing plate..did the crews get loose and it move around?? Points or solid sate ignition?? Check it all and report back.

[Big T]

Igniter gone bad

[RobG1970]

I have a 1980 GS 550E. It sat for many years. I did the " 20 years worth of maintenance " on it .... rebuilt carbs, rebuilt brakes, wheel bearings, valve adjustment, all new clutch plates and a seemingly endless list!! The bike ran fine for about 500 miles. Tonight I drove about a mile and it started having a slight cough and hiccup. I checked the fuel. Valve on, plenty of juice in the tank. Then all of a sudden the hiccup-cough turned into .. It won't rev and backfires, but idles fine. I sent my son back to fetch the van and I took it home. I pulled the plugs and they looked fine. I checked for spark and there appeared to be none... then there was, wasn't, was , wasn't. Then there was and it stayed, but still backfired and won't rev. Any clue were to start!! I am a vintage dirt bike guy, this is my 1st vintage street bike so, ... where to begin??

confirm the plug wires are on the correct plugs.. (yep, been there, done that)

[AJ]

Definitely sounds like ignition to me.

Check for corrosion on the low tension leads (small wires - 12V and ground) to your coils.

Check that the spark plug caps are making good connection to the high tension (fat wires) off the coils. These get worse with age. They screw into the wires and vibration kills the internal connection with time. You can often unscrew them, clip half an inch off the high tension lead, and then screw the caps back on.

Don't remember if this is points or electronic ignition. If points, the point gap and timing could be off, the points severely pitted, etc.

If electronic, then igniter as BigT suggests. Also, everything ChuckH suggested. But I'd start right at the coils.

[Steve]

Did you try turning the petcock to REServe?

.

[Gateway]

I connected a fuel line to the fuel valve and verified that there is excellent flow. the wires are on the correct plug and it does not have points.

[Gateway]

How can you diagnose/verify if the igniter is bad?

[Big T]

when it starts misfiring to the point it's shooting flames out

There's a procedure in the shop manual

Did you download a manual from the BassCliff site?

[Gateway]

No I didn't!! I forgot about that Thanks! There were actually flames shooting out too. Does that sound like a bad igniter?

[Gateway]

One last question! Will an igniter from a different model work ( 750, 1000 etc )

[Gateway]

My solution

On all my vintage dirt bikes I run a PVL ignition, When a machine gets to br 20 plus years old the OEM parts are just not reliable. So with that in mind I bought a Dynatek digital ignition system. Hopefully it won't be a PITA to install. I will let you all know how it works when it arrives!!

[Big T]

That's a good idea

The ignitors, if available, are mucho expensive

[Gateway]

Well, I canceled the order for the Dynatek 2000 digital ignition. After speaking to a rep at Dynatek, I found out all i need is the Dyna S-3 kit. It replaces the original stator plate and pulse coils, eliminates the igniter box and is SIMPLE to install. The best thing... it was only $133.00 + tax cuz I live in NY! I bought it from Z1 Enterprises wich is only about an hour away from where I live. I have it all installed and she fired up NO Problems!! The engine has never run this good since I have had it. I highly recomend the swap for ANYONE with a 550, 750, 850, 1000, or 1100. The best $133.00 you can spend!!