Hey Guys,

So I finally got an air filter in the mail a couple of days back, so I put it in the air box, put the tank back on, connected the hoses to the right places, put the battery back on and tried to start up my 1989 GS500 to no avail - I kept trying for about five minutes.  I confirmed the following:

-Fuel is flowing to the carbs
-Lights dim upon trying to start
-PRI and ON do not seem to make a difference
-Choking also does not seem to make a difference
-Oil light turns on as normal when keys are set to ignition but when trying to start, after a second it turns off but turns back on after several seconds.
-Engine started up for about a second and then died shortly after (after it 'died' it immediately went back to trying to start) - this happened twice.  I can't seem to make it happen again.

What's strange is that it started up with very minimal coaxing of the throttle about 3 weeks ago (no air filter installed then and this was after I had rebuilt the carbs).  The bike has been used sporadically over the past couple of years but when I started it up then, she ran beautifully. 

Any ideas? Any sort of insight would be greatly appreciated!

Drain the carbs, hoses, tank. Fresh gas in there.
Replace the spark plugs.
Check the oil.
Jump it from a car battery.

Got spark ?
Got gas ?
Got choke ?

I'd bet on a broken igniter wire or water in the gas/carbs myself.

Good luck !

Great!  It works now.  It turns out the previous spark plugs were cold plugs meant for racing - given that the weather is 40 degrees, that's probably why it wasn't starting.  So I went on my first ride last night - wow!  Lot of fun!  One thing though... It doesn't seem to have that "oomph" that I thought was possible with this bike.  For example, when I was traveling down the road at 30 mph and I quickly wanted to speed up to 40, the throttle would seem quite unresponsive and overall sluggish and slowly reacting - then again, I think I was in 3rd gear and only pulling 3K RPMs.  I guess I'm too used to driving a car but I do have some speculations...

Either I'm too used to driving a car and not willing to take up the RPMs to a higher amount at a lower gear for some quicker acceleration... OR the petcock valve seems to be messed up and would starve on the "ON" position even when idling so if I transfered it over to "PRI" it would work fine BUT when I was putting everything back together I took the petcock valve with nothing connected to it, put it on prime and blew through the hose port on the back-end of it.  I don't know if it's supposed to be unrestricted, but I had to blow somewhat hard to get any air through it.  So either it's me not being familiar with a motorcycle or it's the petcock - or maybe even both!

Any thoughts?

I would also advise anyone changing spark plugs to change to Iridium ones. My bike was having misfiring problems, was hard to start even though plugs were not fouled. I swapped to Iridium plugs (reasonably more expensive than standard copper core) and will never go back. They are impressive the spark is about 10 times stronger and starts just touching the button whether its freezing cold or whatever. No choke or anything they are excellent. Just a top tip for those planning on changing plugs!

Quote from: OPTheory on October 09, 2007, 09:44:47 AM
... It doesn't seem to have that "oomph" that I thought was possible with this bike.  For example, when I was traveling down the road at 30 mph and I quickly wanted to speed up to 40, the throttle would seem quite unresponsive and overall sluggish and slowly reacting - then again, I think I was in 3rd gear and only pulling 3K RPMs.  I guess I'm too used to driving a car but I do have some speculations...

You won't have much power at 3K rpms. Power doesn't really start much below 4K. For cruising around, I try to keep it between 4-5K, if you want to play a bit, keep it between 5-8K. There isn't much reason to go beyond 8K unless the engine's been modified, even though the redline is at 11K.

Quote from: Kasumi on October 09, 2007, 10:03:25 AM
I would also advise anyone changing spark plugs to change to Iridium ones. My bike was having misfiring problems, was hard to start even though plugs were not fouled. I swapped to Iridium plugs (reasonably more expensive than standard copper core) and will never go back. They are impressive the spark is about 10 times stronger and starts just touching the button whether its freezing cold or whatever. No choke or anything they are excellent. Just a top tip for those planning on changing plugs!

*what's the part number description for NGK iridium plugs for the gs500E?

thanks...

Quote from: jp on October 09, 2007, 10:12:16 AM

Quote from: OPTheory on October 09, 2007, 09:44:47 AM
... It doesn't seem to have that "oomph" that I thought was possible with this bike.  For example, when I was traveling down the road at 30 mph and I quickly wanted to speed up to 40, the throttle would seem quite unresponsive and overall sluggish and slowly reacting - then again, I think I was in 3rd gear and only pulling 3K RPMs.  I guess I'm too used to driving a car but I do have some speculations...

You won't have much power at 3K rpms. Power doesn't really start much below 4K. For cruising around, I try to keep it between 4-5K, if you want to play a bit, keep it between 5-8K. There isn't much reason to go beyond 8K unless the engine's been modified, even though the redline is at 11K.

I'll be sure to keep that in mind.  Thanks!

But do you think that restricted valve might be playing a role in this too?  Again, when I blew through the reserve hose inlet while it was set to "PRI", it seemed pretty constricted - certainly not as good as having a free-flow to the carbs.  The 200cc dirtbike I rode at the MSF course seemed to just be so much more responsive so that's why I speculate this could be the cause.

For NGK Iridium Spark Plugs. Use the following link you have to put in your model, year, etc.... and then it will show you the copper core and then the iridium one. Go to the auto shop and find your number

Part Finder

Ok I followed the part find through and found that your spark plug numbers are:

Copper Core (standard plugs) = DPR8EA-9

Iridium Plugs = DPR8EIX-9


You might want to check as i don't have an GS500

Ok lets look at it this way.
5.0 gallons in a tank will take you 200 miles a tank @ 40MPG (I get around 48mpg)
so at 60MPH you will travel about 3.33 hours to burn 5.0 gallons.
So 5.0/3.33= 1.50gallons an hour
Then 1.50/60=.025 gallons an minute or 6.4 Tablespoons a minuite
Then 6.4/60= .1066 Tablespoons a second.
So your petcock only needs to pass around one tablespoon every 10 seconds to keep you going 60 miles an hour.
So I leave it to you to tell us if you think it can do that.

The "ooomph" will come in around 6K on mine. It will often die if I let off the clutch with any speed at rpm's less than 3k. It is hard to compare a GS500 with a dirtbike, the dirtbike will have a lot more get up and go in my opinion. If you want more power you will have to spend some cash and do a filter/exhaust/jet change. The sound alone is worth the money.

Quote from: Oklahoma_Mike on October 10, 2007, 06:36:15 AM
Ok lets look at it this way.
5.0 gallons in a tank will take you 200 miles a tank @ 40MPG (I get around 48mpg)
so at 60MPH you will travel about 3.33 hours to burn 5.0 gallons.
So 5.0/3.33= 1.50gallons an hour
Then 1.50/60=.025 gallons an minute or 6.4 Tablespoons a minuite
Then 6.4/60= .1066 Tablespoons a second.
So your petcock only needs to pass around one tablespoon every 10 seconds to keep you going 60 miles an hour.
So I leave it to you to tell us if you think it can do that.

Well, hello there, its Sunday, I can't do math. You must be correct then.

Keep in mind your battery isn't being charged (much) below 4-5000 rpm. If you want peak power, that's between 6800 and 8000, and directly afterward it tapers off FAST.

A longish 'blurp' is all that's needed to jump from 30-40 MPH if you're keeping the revs up around 5,000-6,000.

My bike is different from yours, and theirs, and hers, so YMMV.

Quote from: ohgood on January 13, 2008, 12:20:51 PM
Keep in mind your battery isn't being charged (much) below 4-5000 rpm. If you want peak power, that's between 6800 and 8000, and directly afterward it tapers off FAST.

A longish 'blurp' is all that's needed to jump from 30-40 MPH if you're keeping the revs up around 5,000-6,000.

My bike is different from yours, and theirs, and hers, so YMMV.

I wouldn't agree with the first part of what you said. I recently checked the charging system on my 2004 GS 500 and I found that my GS charges the battery very well when idling (1400 RPMs) it gives about 14V which is plenty to fully charge the battery.

Also GS5000 has most power at 9000 RPMs. In my rejeted bike I have most power between 5-6K RPMs and between 8-9K RPMs; 6-7K are worse and 9-11 are the worst, at least in my case. So if you need quick acceleration you have to keep the RPMs kind of high (at least 4-5K RPMS).

cheers
KML