Hey, new to the site, just bought a '93 GS 500. It starts and runs.....kind of.
It'll turn over a couple times, maybe start, and then die.
The seller said it needed new carburetors, but i cant imagine why. I would think they would just need calibration :dunno_white:.
I'd like to fix it myself, if possible, before paying $60 an hour for someone else to do it.
Any ideas? Help me out!
Quote from: SmithvilleFlats on May 20, 2008, 11:10:46 AM
Hey, new to the site, just bought a '93 GS 500. It starts and runs.....kind of.
It'll turn over a couple times, maybe start, and then die.
The seller said it needed new carburetors, but i cant imagine why. I would think they would just need calibration :dunno_white:.
I'd like to fix it myself, if possible, before paying $60 an hour for someone else to do it.
Any ideas? Help me out!
Are you using the choke to start the bike (it's the lever by the left grip)?
If it's been sitting awhile, the bike will likely need new sparkplugs and fresh fuel at a minimum. The battery may also be weak/dead. Most likely, you will have to remove, disassemble, and clean the carburetors.
I'm not sure why new carbs would be required unless the previous owner did something to damage them? Best thing to do is take them off and have a look inside.
Keep us posted and feel free to ask any questions.
I have never replaced carbs on a motorcycle. I can almost guarantee that there is varnish inside the pilot jets. just take them apart and remove the jets. clean them with a strong carb cleaner. make sure you can see through the jet after wards. good luck!!!!
Quote from: 04gs on May 20, 2008, 01:44:45 PM
I have never replaced carbs on a motorcycle. I can almost guarantee that there is varnish inside the pilot jets. just take them apart and remove the jets. clean them with a strong carb cleaner. make sure you can see through the jet after wards. good luck!!!!
+1,000
There are plenty of write-ups on this site that deal with cleaning carbs.
Here's a link to cleaning.
http://gstwin.com/carb_work.htm
Carb float height check.
http://www.bbburma.net/FloatHeight.htm
Carb balancing.
http://cgi.stanford.edu/~sanjayd/gs500/Maintenance/5CarbSync
Another problem that comes up with older bikes is the vacuum operated petcock.Vacuum operation can be eliminated.I do the conversion for $10 includes return shipping.
Here's a couple links to remedy this.
http://gstwins.com/gsboard/index.php?topic=19363.0
http://gstwins.com/gsboard/index.php?topic=36958.0
Thanks!
I got the carbs off, and i can see why someone would just replace them.
The owner had the choke cable jb welded to the carb body, and it looks like he patched it in one spot.
I got them cleaned up so they should be good to go.
I also picked up a fuel filter because there was some grime coming out of the tank, so I'll have to clean that up too.
I'm guessing there will be some vacuum problems, also. The carbs' intake gaskets were a little cracked, but we'll see.
Some people might say it's a little rough, I just say it's got character! O0
Cant wait to get this thing on the road!
Quote from: SmithvilleFlats on May 22, 2008, 01:03:46 PM
Thanks!
I got the carbs off, and i can see why someone would just replace them.
The owner had the choke cable jb welded to the carb body, and it looks like he patched it in one spot.
I got them cleaned up so they should be good to go.
I also picked up a fuel filter because there was some grime coming out of the tank, so I'll have to clean that up too.
I'm guessing there will be some vacuum problems, also. The carbs' intake gaskets were a little cracked, but we'll see.
Some people might say it's a little rough, I just say it's got character! O0
Cant wait to get this thing on the road!
:o pics?
Tank grime, like rust? Or sludge, like water on the bottom? Either way, in addition to the fuel filter, you probably want to get rid of the old gas and rinse out the tank with some fresh stuff.
Post a pic of the broken choke area on the carb.Someone may have a good carb body or slide.
Just patched up the carb and put it back on. It should work fine. I'll take pics next time I take it off.
New issue: I took the spark plugs out and they were coated with black oil, so I'm guessing there's a leaky piston ring or valve somewhere.
How common is this? What will it take to fix this?
Thanks
Quote from: SmithvilleFlats on May 27, 2008, 09:27:33 AM
Just patched up the carb and put it back on. It should work fine. I'll take pics next time I take it off.
New issue: I took the spark plugs out and they were coated with black oil, so I'm guessing there's a leaky piston ring or valve somewhere.
How common is this? What will it take to fix this?
Thanks
it MAY just be that Previous Owner changed the main jets and used too large ones. The plugs would be then covered with black substance. If this is the case you will be too rich on fuel and you need to change the jets to smaller ones. WAIT for others opinion though, I'm not pro so I may be wrong
good luck and I hope to see the pics soon!
Kamel
Quote from: SmithvilleFlats on May 27, 2008, 09:27:33 AM
Just patched up the carb and put it back on. It should work fine. I'll take pics next time I take it off.
New issue: I took the spark plugs out and they were coated with black oil, so I'm guessing there's a leaky piston ring or valve somewhere.
How common is this? What will it take to fix this?
Thanks
The following chart shows spark plug colours and conditions:
(http://bbburma.net/Scans/Haynes_SparkPlugChart.jpg)
Where do you fit?
If the spark plug is in fact oily, a compression test will help to determine the condition of the rings/valves.
Definitely oil fouling on both plugs.
Quote from: SmithvilleFlats on May 27, 2008, 12:34:09 PM
Definitely oil fouling on both plugs.
Yuck. :(
This thread explains how to use a cylinder compression test to determine if the problem is the piston rings or the valves:
http://gstwins.com/gsboard/index.php?topic=38986.msg438007#msg438007
More info on compression tests:
http://gstwins.com/gsboard/index.php?topic=40110.0
Well I went out and got my compression tester and it turns out it doesnt fit the smaller spark plug hole on bikes, so I'm still not sure what the problem there is.
After perusing the pages of this site, it's become clear that my fuel system is not at all stock.
The fuel runs from the gas tank here...
(http://img160.imageshack.us/img160/6449/p00080yv7.jpg) (http://imageshack.us)
...directly into the carbs here.
(http://img369.imageshack.us/img369/981/gaslinevl2.jpg) (http://imageshack.us)
Weird?
The previous owner probably had fuel starvation problems and solved them by using that by removing the frame-mounted petcock and replacing it with an "aftermarket" petcock (the red and black one). The current setup seems to draw fuel from the reserve outlet on the tank. What is the other outlet connect to?
Use the info on Kerry's website to verify that the fuel hose routing is correct:
http://www.bbburma.net/FuelHoseRouting.htm
The second outlet on the tank's petcock is plugged. Also, the vacuum hose to the left carb does not appear to be there.
Quote from: SmithvilleFlats on June 04, 2008, 12:33:38 PM
The second outlet on the tank's petcock is plugged. Also, the vacuum hose to the left carb does not appear to be there.
With this setup, the vacuum hose to the left carb is not necessary. The vacuum hose is normally used to actuate the frame-mounted petcock, allowing fuel to flow only when the engine is running.
http://cgi.stanford.edu/~sanjayd/gs500/Upgrades/Petcock
However, the vacuum port on the left carb should be plugged. Otherwise, the carb will suck a lot of excess air and will run lean.
Quote from: SmithvilleFlats on June 04, 2008, 10:56:55 AM
Well I went out and got my compression tester and it turns out it doesnt fit the smaller spark plug hole on bikes, so I'm still not sure what the problem there is.
Sorry, I forgot to comment on this before: the compression tester usually has a screw-on adapter that will allow you to use it in the smaller plug. If your tester didn't come with this piece, it may be available separately.
If you have or can get a stock petcock convert it to non vacuum.I do this mod for $10 that includes return shipping.
http://gstwins.com/gsboard/index.php?topic=19363.0
Or you can get a cheap replacement.
http://gstwins.com/gsboard/index.php?topic=36958.0
So am I going to have to replace the petcock or is this setup workable?
Quote from: SmithvilleFlats on June 05, 2008, 08:33:56 AM
So am I going to have to replace the petcock or is this setup workable?
The setup looks workable. The important thing is that fuel gets delivered to the carbs. The vacuum port of the carb should be plugged to prevent an air leak.
You can use the float height check to verify that fuel is getting to the carb bowls and to confirm that the float heights are OK:
http://www.bbburma.net/FloatHeight.htm
If your spark plugs are covered in oil, you have bigger problems than incorrect fuel hose routing.
This is a bit embarrassing.
I got the bike running and checked the spark plugs before turning it over again, and what appeared before as oil on the spark plugs I now believe to be unburnt gas on black powder. :oops:
The bike also shoots out black smoke which would be consistent with a rich mixture.
Obviously this is much simpler than leaky piston rings or valves, so I'm not upset that I was wrong.
I'm looking into getting new carbs since mine are in a somewhat shady condition.
I'm going to check the float height first.
What else should be checked/adjusted?
Quote from: SmithvilleFlats on June 05, 2008, 08:33:56 AM
So am I going to have to replace the petcock or is this setup workable?
Looks like exactly what I've done to mine - he used a vacuum cap to seal one fuel tank outlet, running the tubing from the reserve outlet to the filter, cutoff valve , to the carb. Mine works ok, you just don't have reserve warning of low fuel. Put a filter in that tubing somewhere and change it frequently if your tank is rusty.
I like the blue hoses they look fancy I may go get some. As far as your setup goes keep an eye on your tripmeter cause once you start boging down that means your out of gas. maybe you shoudl go two hoses out of the tank chicken and do a small selector valve so you have both main and res.
So here's what's wrong now:
-Bike starts good, but then randomly revs up to around 7k rpm when given throttle.
-Then, once it starts getting warmed up, it dies.
-Still smoking black.
:2guns: :cry:
Suggestions are appreciated.