Won't start

[New_rider]

Hey,
I'm working on my 81' GS550L. It was running the first few days i had it but then it began sputtering and wouldn't run. I can't get it to start anymore. The spark plugs are good, i can smell gas coming out of the exhaust when i try and start the bike, and the carbs are on tight. Does anyone have any ideas on what to try?

[fgh]

Get a spark plug and plug it into each wire and crank it. Look to see if the sparks are all relatively equal in brightness and frequency. Make sure the base of the plug is on the engine when cranking. Never crank a GS with a loose plug wire.

[New_rider]

I tried that and everything seems to be fine in that department

[SPARKSS]

Howdy New rider.....The fact that you can smell raw gas in the exhaust means it's probably flooded........IF it was running ok previously, and nothing has been altered, then it's probable that the immediate problem is that you have fuel fouled spark plugs (which likely won't fire in the open air let alone under compression). If that was mine (and it ran ok before and nothing was changed), I'd pull those plugs and confirm whether they're wet and black (fouled) - At this point it'd depend on what I had to work with......if I had new plugs I might try them maybe after disconnecting or pinching the fuel line (so as to prevent an immediate refoul). If it starts, it'll smoke like a bugger burning off the excess fuel and as a result of that fuel washing the cylinder walls down you may have some oil smoke from temporary blowby. If it didn't start, and you are sure you have good spark at all plugs, I might (with the fuel shut off per above) remove the air filter (confirm it's not plugged!) and run some propane into the air box (unlit small propane torch) and see if it'll start like that (this will NOT foul the plugs)......if it fires right up and seems to run strong on this then you know you have a fuel flooding problem but the rest of the engine is basically ok. If it doesn't, then you can start to think about what's missing from the basics of.......compression.........mechanical timing.......ignition.......and ignition timing (as you've already eliminated fuel).

How'd you make out?

[BassCliff]

Hey howdy hey!

Mr. New_rider,

Let it be known that on this day you are hereby cordially and formally welcomed to the GSR Forum as a Junior Member in good standing with all the rights and privileges thereof. Please note that "good standing" implies pictures! :-D

I'm just going to share a couple of things I've learned since joining this fine group of motorcyclists. I'd also check your petcock. If it's leaking you may also have gas in your oil. Don't run the motor if there's gas in the oil. Please change it first. If necessary, I like the idea of buying a new petcock rather than trying to rebuild. The petcock should be passing fuel only when it is supplied a vacuum from the carburetor. Don't use an inline fuel cutoff valve. You'll forget to turn it off and be right back where you started.

Thanks for joining us. There are lots of GS riders here who are a lot smarter than I when it comes to fixing these bikes. But the generous and helpful folks here are teaching me to be a better motorcycle mechanic and a better motorcycle rider. You'll like it here.

Thank you for your indulgence,

BassCliff
(The unofficial GSR greeter)