Hello to all, new here to the forums and basically a novice when it comes to anything mechanical (forewarning).  I just bought a 93 GS500E two weeks ago and I have started to encounter problems with the bike hesistating and then stalling.  Whenever I get the bike to about 5000 RPMS it bogs out and then it will start to hesitate and stall.  After the stall it takes about 10 to 15 minutes to get the bike to start and then it seems like it drives fine.  Does anyone know what the problem could be and maybe what needs to be checked/fixed?

My Dad does all the mechanical work on my vehicles and any help may assist him in diagnosing the problem.  He thinks it could be a fuel line or the carburetors from the description I've given him.

Here's a picture of my motorcycle:

I'm guessing that with that ebay car muffler that's on it; it's running extremely rich or not getting enough fuel. I would probably start with the carbs, checking to see what size jets it has in it. With that free flowing car muffler, i can't begin to tell you were to start but with your dad's knowledge and your; I'm sure you two will figure it out.   

I was thinking the same thing about the muffler.

Think about making or buying a restrictor for that muffler and make sure the carbs are jetted for it. What's on the intake?

Yep, if it doesn't have a silencer; find one for it and start there. I'm sure that wouldn't fix the probelm but it should help tremendously.

Dad just checked the engine compression and it's low at 105 lb/in^2 (Standard is btw 142 to 199, right?).  It needs new spark plugs and I think I inherited a piece of crap.  Also, the muffler is a car muffler (3A Racing), so that's probably something else that will need to be fixed. 

Anyone want to buy a gun?

Oh man, I hate that problem. Fix it, and let me know what it was so I can fix my bike!

Quote from: tt_four on June 11, 2009, 01:53:32 PM
Oh man, I hate that problem. Fix it, and let me know what it was so I can fix my bike!

I won't even know what he does when he fixes it.  I'm a moron when it comes to anything mechanical.

I had the same exact problem with my 92 right after I bought it and started looking around to check everything out.  I figured it was the carbs or something so I took off the seat and tank and got a good look at them and they looked completely fine.  At that point I figured I would just take it to someone who knew what they were doing, but when putting everything back together I realized that someone had connected the tank drain hose to the top T on the carbs, and the hose that goes to the top T on the carbs was just in there not connected to anything.  I re routed the hoses and seemed to get rid of the problem but the bike still did run a little bit rough.  After an oil change and new NGK iridium spark plugs the bike is running so much better.  Still have to replace the air filter which should take care of the rest of it I'm hoping. 

Anyway, long story short, pull up the hose routing diagram from the wiki and make sure that they are all run correctly.

I'm painting my basement this weekend, which means I can spend next week putting up the pegboard, hang up my tools, put my work bench back together, and then next weekend I can start pulling the GS apart so I can ride it again! I'll make sure I look into those hoses as well.

Not a bad looking bike, and welcome to the board!

Before you have Dad tear it apart, try to save him some work.  He works hard all day and he will appreciate it, believe me.

Try running it with the fuel petcock set to PRI (prime) instead of ON or RES.  The vacuum operated petcock is notorious for getting cruddy inside and not opening all the way, strangling fuel flow.  Setting it to PRI by-passes the vacuum operated safety feature and allows gas to flow to the carbs without any restriction.  If it runs good set to PRI, you need to clean your petcock.  Some change them with manual petcocks.  Putting 2 ounces of Marvel Mystery Oil or Seafoam in each tank of gas has been known to help this sticking valve.  MMO worked for me.

As for the low compression, it's possible the valves have never been adjusted.  How many miles are on the bike?  If they're too far out of adjustment, particularly the exhaust valves, they can stop seating completely, losing compression.  They should be checked before you tear the engine apart.  If your valve seats are worn to the point where they're way out of adjustment, it will be hard to start.

Good luck and keep us posted!

Quote from: bill14224 on June 11, 2009, 07:23:15 PM
Not a bad looking bike, and welcome to the board!

Before you have Dad tear it apart, try to save him some work.  He works hard all day and he will appreciate it, believe me.

Try running it with the fuel petcock set to PRI (prime) instead of ON or RES.  The vacuum operated petcock is notorious for getting cruddy inside and not opening all the way, strangling fuel flow.  Setting it to PRI by-passes the vacuum operated safety feature and allows gas to flow to the carbs without any restriction.  If it runs good set to PRI, you need to clean your petcock.  Some change them with manual petcocks.  Putting 2 ounces of Marvel Mystery Oil or Seafoam in each tank of gas has been known to help this sticking valve.  MMO worked for me.

As for the low compression, it's possible the valves have never been adjusted.  How many miles are on the bike?  If they're too far out of adjustment, particularly the exhaust valves, they can stop seating completely, losing compression.  They should be checked before you tear the engine apart.  If your valve seats are worn to the point where they're way out of adjustment, it will be hard to start.

Good luck and keep us posted!

Thanks.  I'll attempt the petcock later in the day after I get off work.  The bike has 11,*** miles on it, so it is possible that the valves need to be adjusted.

Going for a ride today and I'm going to have the petcock set to PRI to see how it runs.  I will update if I encounter any problems or if I don't.

Dad came over to replace the spark plugs, but the bike wouldn't hold an idle, so we put the old ones back in.  After that the bike idled fine, but I still need to get new spark plugs.

Well I kept the bike set to PRI and it drove wonderful.  The only down side was that the bike would sometimes idle at 2000 RPM, but that's the only thing that I can think of that was somewhat off.

The exhaust doesn't seem to affect the bike whatsoever, so I don't know if it should even be replaced. 

All in all it turned out to be a good day.

With my petcock set to PRI, will I burn more gas?  Also, I seem to be smelling gas from the bike, is that b/c of the petcock setting on PRI or maybe there might be a gas leak?

if you smell it, there's a leak. Might want to have Pop's check the floats on that bad boy. Also, check your gas lines. On a bike that old, i'm sure you have some dry rotted lines.

end of line....

Thanks for the advice.

Well I am about to throw my bike into the river b/c I'm going to have to put too much money into it.

At first I thought I only needed a rear tire, so I bought one.  Of course that's not the only thing it needs.  Now I have to buy a needle and seat kit, a rear brake rotor, rear brake pad, spark plugs, kreem (for the rusted fuel tank), bowl gaskets, o-rings for the carburetors, and an air filter.  I knew I would have to spend money, but this is getting ridiculous.

And to make matters worse, while trying to take the fuel cap off the tank I dropped an alan wrench into the tank and I now cannot get the wrench out.

<----if this were my bike.

From the pic that you posted of the bike, it's not that bad. It may take a little time but it will be well worth it. The biggest enemy of the GS is neglect/not being ridden. Once you fix these, you have a pretty cheap and reliable bike. And who said you needed a rear rotor? Any pics?

The rear rotor has grooves.  My Dad said it should be replaced b/c of the grooves.  Is this correct?