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Hello everyone this is my first post, and it's a shame that it has to be about a problem rather than the joy of riding a GS 
Please bear with my long explanation :P
Anyways, I bought this 78 GS550 last week in really excellent cosmetic shape, but less than excellent mechanical shape... In retrospect I probably should have had it checked out by a mechanic, but I needed a bike quick and this one looked absolutely perfect to me.
In any event, it started and ran fine, both electric and kick in the guy's driveway who I bought it from but as soon as I got it home (200 miles in the back of a pickup truck) it wouldn't start. I figured out that the vacuum petcock wasn't working and it was dumping tons of fuel into the cylinders through the carbs somehow... I guess a float bowl was stuck open or something. I got it running by changing the plugs that got wet with gas and it ran ok for a while, started stalling after about an hour of solid riding at moderate speeds (topping arround 50, but mostly arround 30). I talked to the previous owner and he said he thought it was overheating because I was letting it idle too long. (I left it running for a couple minutes when I called my girlfriend.) Maybe he was right, because it tried to die everytime I would coast up to a stop sign, but it started right up again when it died. The next day however it needed new plugs again (petcock) and ran similarly. On the third day I was so fedup I called every bike shop in town until someone told me to check the petcock, and sure enough as soon as I pulled the gas hose with the engine off gas started spirting out.
So fast forward a couple days, I scored a petcock on eBay, and it's not leaking anymore, but the problems I am having are almost more serious in a different way. Before continuing I would also like to add the side note that I know the carbs are bad and need replacement, a rebuilt won't cut it because some of the fasteners that screw into the carb body are broken off. It's running super rich and that might cause some of my problems but not to the extent they have developed to.
I changed the oil before installing the new petcock, because gas must have seeped in past the piston rings. So it starts now, but it stalls very quickly, far worse than before with the bad fuel valve. I was trying to ride it off campus and made it down to the base before it died. I was cruising down hill at about 50 MPH and as soon as I started easing off the throttle I got that ugly feeling that the engine was quitting, and sure enough it was long gone before I came to a stop. I managed to get it running stably(somehow, feathering the choke and throttle...) and drove it back up to my room. It has done the same thing repeatedly in various situations since then. It will die in about 2-5 minutes or less no matter where I am running it...
So here are my questions, beyond which I am open to any suggestions as well. I know I need to do the carbs, but maybe it would make sense to have someone in town look at it. I am condifent in doing my own work as long as I have a purpose and know that I am attacking the cause of the problem.
1. Is the filter in the petcock necessary? The reason I ask is that the replacement petcock I bought on eBay didn't come with one, and I had to remove some excess plastic from my old filter to press it in, and it still wasn't a very good fit. It's strange because it was listed as being a 78 petcock. In any event I think this stalling could be caused by lack of fuel what do you think?
2. Could trying to start the engine with too much oil (1/2 quart maybe..) in it cause problems like this after the excess oil is removed?
TIA, to those of you who took the time to read this long, boring explanation. I am open to and all suggestions.
-Simon
Please bear with my long explanation :PAnyways, I bought this 78 GS550 last week in really excellent cosmetic shape, but less than excellent mechanical shape... In retrospect I probably should have had it checked out by a mechanic, but I needed a bike quick and this one looked absolutely perfect to me.
In any event, it started and ran fine, both electric and kick in the guy's driveway who I bought it from but as soon as I got it home (200 miles in the back of a pickup truck) it wouldn't start. I figured out that the vacuum petcock wasn't working and it was dumping tons of fuel into the cylinders through the carbs somehow... I guess a float bowl was stuck open or something. I got it running by changing the plugs that got wet with gas and it ran ok for a while, started stalling after about an hour of solid riding at moderate speeds (topping arround 50, but mostly arround 30). I talked to the previous owner and he said he thought it was overheating because I was letting it idle too long. (I left it running for a couple minutes when I called my girlfriend.) Maybe he was right, because it tried to die everytime I would coast up to a stop sign, but it started right up again when it died. The next day however it needed new plugs again (petcock) and ran similarly. On the third day I was so fedup I called every bike shop in town until someone told me to check the petcock, and sure enough as soon as I pulled the gas hose with the engine off gas started spirting out.
So fast forward a couple days, I scored a petcock on eBay, and it's not leaking anymore, but the problems I am having are almost more serious in a different way. Before continuing I would also like to add the side note that I know the carbs are bad and need replacement, a rebuilt won't cut it because some of the fasteners that screw into the carb body are broken off. It's running super rich and that might cause some of my problems but not to the extent they have developed to.
I changed the oil before installing the new petcock, because gas must have seeped in past the piston rings. So it starts now, but it stalls very quickly, far worse than before with the bad fuel valve. I was trying to ride it off campus and made it down to the base before it died. I was cruising down hill at about 50 MPH and as soon as I started easing off the throttle I got that ugly feeling that the engine was quitting, and sure enough it was long gone before I came to a stop. I managed to get it running stably(somehow, feathering the choke and throttle...) and drove it back up to my room. It has done the same thing repeatedly in various situations since then. It will die in about 2-5 minutes or less no matter where I am running it...
So here are my questions, beyond which I am open to any suggestions as well. I know I need to do the carbs, but maybe it would make sense to have someone in town look at it. I am condifent in doing my own work as long as I have a purpose and know that I am attacking the cause of the problem.
1. Is the filter in the petcock necessary? The reason I ask is that the replacement petcock I bought on eBay didn't come with one, and I had to remove some excess plastic from my old filter to press it in, and it still wasn't a very good fit. It's strange because it was listed as being a 78 petcock. In any event I think this stalling could be caused by lack of fuel what do you think?
2. Could trying to start the engine with too much oil (1/2 quart maybe..) in it cause problems like this after the excess oil is removed?
TIA, to those of you who took the time to read this long, boring explanation. I am open to and all suggestions.
-Simon
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