1st bike in 20yrs

[jkeiley]

I was given a 1981 sx1100g from my brother 3weeks a go, that he had for 2 yrs but could not get running. I have it to the point it will run but has a miss at low rpms on the #1 piston. once I get it up to speed it fires fine. I've traded out the coils and the CDI? box but still have the low speed miss on the timming llight.
Any ideas?
Thanks JK Colorado

[fxrer]

After 2 years of not running, it sure sounds like you have carb problems. These bikes are notorious for dirty carb problems. If #1 cyl is misfiring (left side of bike), since the bike leans that way on the kickstand, that is where dirt, gunk problems first appear.

Probably varnish in the low and mid range circuits. Time to pull carbs and "triple clean” them.

There are countless threads in this forum on how to do this.

Do a search and you will see volumes of info.

Good luck

[MAXIMAN]

Here here...fxrer is dead on. Also I've seen bikes that needed valves adjusted miss in a strange fashion as well. How many miles?

I hope this doesn't sound like a duh!...but what about plug wires and plugs?

[TopCatGr58]

Hey there JKeiley,

Welcome to the gang. To further eliminate the ignition/coils as the problem, you can swap the #1 and #4 plug wires, just put them on the other plugs, cause that coil fires both at the same time, one is on compression, one is on exhaust, so it's just a wasted spark...no problem. Then if it still has the same miss on the same cylinder, then you know it's the carb, not the plug wires and coil.

I concurr with the carb diagnosis as the probable culprit. IF they haven't been worked on by a mechanic before, then the idle/pilot circuit adjusting screws will NOT be accessible, they were capped off at the factory with little brass plugs. You will need to carefully drill thru them, then use a sheet metal screw to screw into it, and then use a plier to pull them out so you can get to the pilot screw. You really need to remove it to do a thorough cleaning of the pilot/idle circuit.

You'll want to get a manual, and read the tech tips before doing this. They are delicate and can be messed up if you aren't careful.

Until you get these instructional documents, you can put some Sea Foam in the gastank to try to help dissolve some of the varnish....but a good disassembly and cleaning will work wonders!
T.C.

[MAXIMAN]

Actually TC makes a good point. When I got Zilla is was missing a little...not bad just a little.

I pour two (2) full cans of Seafoam fuel treatment into an empty tank and only put about 3 gallons of gas on it and drove that out (about 100 miles). That helped a lot. But..........

Have you even checked the air filter. As I recall now Zilla's air filter looked like black death. It was filthy and oily and had dirt dobber nests in it. When I changed the air filter I saw another quantum leap in performance.

[randy]

Hey, Jkeiley,

Your TCI is on it's way back to you.

[jkeiley]

The carbs I've done after reading every thing I could find on them. The miss is on the timing light when it is hooked up. It is like it just wants to skip a fire every 3rd time at low rpms. I will swap out the #4 and #1 and see what that dose.
Thanks
JK

[Czekus21]

If that miss is at the timing light, you might want to check your pickup coils.

[jkeiley]

It looks like the miss went from#1 to #4 when I changed over the wires. I have another coil that I switch out tonight and see if that takes care of it.
Thanks
JK

[TopCatGr58]

Hey Jkeiley,

There's a tech tip about replacing the wires in the coils, if it's firing then it's good, and it's probably just a bad wire, could even be a bad plug cap. Glad you're getting results with your troubleshooting! Keep at it!
T.C.

[jkeiley]

OK it took a wile but I changed out the wires on the coils. Now she is a runner! Just got most of the snow off the roads and got to take her for a short ride. She ran good. Thanks for the help.
JK