Hello,

I recently purchased a D&D slip-on exhaust. I tried to research more about the exhaust, but there is no model # on the exhaust.

However, I found a video of another owner of a GS500F with the same exhaust:
https://www.youtube.com/watch?v=WGpDH2cT6Pg

In the video description the GS500F owner states he didn't need to rejet, but I think I need to do it in my situation.

It seems the bike runs super lean at the moment. I have stock air filter and air box in (I would like to keep these items stock if possible).

Problem: Rolling up to a stop light the bike will stall before I stop completely. Idle RPMS are below 1200 RPM sometimes even below 1000RPM.

I have no idea on how I should approach this rejet stage. I've read through many posts, threads, and even the wiki from gstwins.

I do not know what size of main and pilot jets I should purchase. I would ask the knowledgeable members and gurus on this forum to shed some of their knowledge and opinion on this matter.

Thank you! Your input is much appreciated! 

The only symptoms are a low idle / stalling when you stop? If so, you don't need new main jets (at least, they won't solve your stalling problem). First, try turning your idle screw in so it idles around 1400 rpm. Then try setting your mixture screws to 2.5 or 3 turns out. You have the stock pilot jets, correct? You might have to go more turns out on the mixture screws or even larger pilots.

Once your idle circuit is dialed in, be sure to set the idle back to factory spec (I believe it's 1200 +/- 100 rpm).

Quote from: Big Rich on July 03, 2014, 11:22:57 PM
The only symptoms are a low idle / stalling when you stop? If so, you don't need new main jets (at least, they won't solve your stalling problem). First, try turning your idle screw in so it idles around 1400 rpm. Then try setting your mixture screws to 2.5 or 3 turns out. You have the stock pilot jets, correct? You might have to go more turns out on the mixture screws or even larger pilots.

Once your idle circuit is dialed in, be sure to set the idle back to factory spec (I believe it's 1200 +/- 100 rpm).

Thank you, Big Rich for your help.

Yes, I have low idle and stalling when coming to a complete stop.

I forgot to mention that there is some popping sounds coming from the exhaust when I decelerate. I believe there may be some popping sounds when I accelerate too.

The jets should be stock. The previous owner didn't rejet the bike when I asked him. I will double check tomorrow, and see if I can make the new adjustment to the pilot jet/idle screw.

I will report back asap!

hi iceman86, im from the uk and have recently been having similar problems trying to work out similar jetting for a can i plan to use, if your pilot jets are still the stock 17.5 i suggest fitting 20's, this stops the rpm dips you encounter,

have a read of the jetting wiki if you havnt already.
http://wiki.gstwins.com/index.php?n=Upgrades.Rejetting

"2001 - 2007 Carburetors
The advantage of these newer carbs are the inclusion of a Mid Main Jet that allows finer tuning of the fuel to air ratio of different throttle openings.
YEAR + Jet Size
2001+ Stock - 17.5 Pilots / 60 Mid Main / 127.5 Main
2004+ Stock - 17.5 Pilots / 60 Mid Main / 130.0 Main
These bikes use Mikuni Carburetors / Jets with the following part numbers for their jets:
Pilots = N224.103 or VM28/486 (apparently they are the same)
Mid Main & Main = N102.221

To what degree
A conservative Starting Point for upgraded Jetting (Pilots/Mid Main/Main) for a:
Stock GS500 = 20/60/135
Drop in K&N Air Filter Only = 20/62.5/140
K&N Pod or Lunchbox Air Filter Only = 20/65/142.5
Drop in K&N Air Filter + Sports Exhaust = 20/62.5/142.5
K&N Pod or Lunchbox Air Filter + Sports Exhaust = 20/65/145
Unfortunately Re-Jetting is a black art (so many variables including humidity, altitude, engine condition etc etc) so often much tweaking of jet sizes is needed to find the perfect combination.
See the Matrix for what other users have found to work.
Remember: The GS500 has two carburetors so you will require two of each jets!"


Ive sent a few messages back and forth with Buddha who's the main bloke for jetting advice and he suggested a 132.5 over a 135 main jet, so maby get the 20 pilot jets and 132.5 and 135 main jets as they are dirt cheap to buy.
That way you know your bikes definitely going to be fueling spot on, Buddha is even able to supply a comprehensive kit for your carbs including float bowl screws as the sock ones usually get mangled when you remove them, all you need to to is send him a message.

hope this clears eveerything up

If it drops to below the set idle rpm when you release the throttle and comes back to idle - you're rich.
If you are lean after fully warm, the bike will idle @ 3K or somewhere round that, if it idles 1200 or so when cold.
If it takes longer than 30 seconds in summer to where it will hold idle without choke - you're lean.
OTOH, if it will start without choke in summer - you're prolly a wee bit rich ... if it will do that in winter you're very rich.
Cool.
Buddha.

The above is for jetting @ idle or @ very small throttle opening only. You may be rich there but lean elsewhere ... and you can also be lean there but fine elsewhere.
Cool.
Buddha.

Hello,

Thanks for everyone help on this!

I am little confused and uncertain, but is this the mixture screw Big Rich is referring to?

Note: I have a GS500F 2005.

Quote from: Big Rich on July 03, 2014, 11:22:57 PM
The only symptoms are a low idle / stalling when you stop? If so, you don't need new main jets (at least, they won't solve your stalling problem). First, try turning your idle screw in so it idles around 1400 rpm. Then try setting your mixture screws to 2.5 or 3 turns out. You have the stock pilot jets, correct? You might have to go more turns out on the mixture screws or even larger pilots.

Once your idle circuit is dialed in, be sure to set the idle back to factory spec (I believe it's 1200 +/- 100 rpm).

Taken from: http://gstwins.com/gsboard/index.php?topic=56601.0

Here are pictures of my carbs:



Would anyone be kind enough to help me confirm and identify the location of my mixture screw? I am concern I may taper with the wrong screw

Yours are basically in the exact same position. And yours are all nice and shiny brass, not dull and corroded like the first pic.

Quote from: Big Rich on July 07, 2014, 04:24:54 PM
Yours are basically in the exact same position. And yours are all nice and shiny brass, not dull and corroded like the first pic.

Thank you very much for replying back and answering my question, Big Rich!

I will make the adjustment and go for a test ride. I will report back asap on how she runs with the new adjustment.

Thank you to everyone once again!

Hello,

I made some adjustments with the mixture screws. I did 4.5 turns.

I went for a quick ride after warming up the bike and the results are:

1) I haven't stalled yet upon coming to a completely stop.
2) The popping sounds still occurs when I am decelerating.

Correct me if I am wrong, but the mixture screw on the GS500F 2005 controls the amount of fuel that flows thru only right?

Since I did 4.5 turns on the mixture screw and I no longer stall when coming upon a complete stop. I am and should be running a little rich now?

If that case should I reduce the amount of fuel being intake? Possible down to 3 to 3.5 turns? I am idling steadily between 1300-1200 RPM I believe.

If you need 4 turns on your pilot screws, you probably need to go up a size on your pilot jets. I'd never go past 4 turns myself.
If it still lags when you blip the throttle, larger pilots would be my guess, if everything else being OK.

Hello again,

Just follow up with some updates:

1) I went for a quick ride. Warmed up the bike for about 35-45 seconds. Idles around 1200 RPM.
2) The first 2-3 few stop lights I stalled as I came to a complete stop. The RPMs were struggling to stay at 1200 RPM (it was hanging low 1100-1000 RPM). I had to adjustment the idle screw on the spot a few times.
*The only way to prevent the bike from stalling as I come to a complete stop is to give a little gas so the RPM hovers above 1200 RPM.

I stopped at a nearby friend's house for 20 minutes, and then I continue to ride to a nearby coffee shop.

1) Upon starting up the bike the idle speed was hanging steadily at 1500 RPM. I couldn't bring it below that with the idle adjustment screw.
2) As I rode home coming to a complete stop the bike didn't stall, and was steadily hanging at 1200-1100 RPM.

Am I not giving enough time for the bike to warm itself up?

Below is a video I made before I went home to showcase the popping sounds as the RPM descents:
https://vid.me/OmA

Would simply up-sizing only the pilot jets help resolves the 1) stalling issue and 2) popping sound from exhaust? I am uncertain on how to proceed at this point

Quote from: ace50 on July 08, 2014, 05:46:48 AM
If you need 4 turns on your pilot screws, you probably need to go up a size on your pilot jets. I'd never go past 4 turns myself.
If it still lags when you blip the throttle, larger pilots would be my guess, if everything else being OK.

The popping from the exhaust isn't THAT big of a problem. There's a very good chance your stock exhaust popped a little bit, but the quieter muffler hid it.

Try putting in a larger pilot, and then fine tune with the mixture screws. You may be left with slight popping on decel, you might not.

Quote from: Big Rich on July 08, 2014, 07:16:53 PM
The popping from the exhaust isn't THAT big of a problem. There's a very good chance your stock exhaust popped a little bit, but the quieter muffler hid it.

Try putting in a larger pilot, and then fine tune with the mixture screws. You may be left with slight popping on decel, you might not.

Thanks, Big Rich and everyone else

I guess I will try to get a pair of pilot jets @ 20 and main jets @ 135. I think much places online requires you purchase four jets at a time.

I will report back as soon as I get them installed and tuned. I am just concerned about the stalling at red lights. Could be dangerous

Quickly scanned thread, didn't see you mention if you have checked or know where your valves are set at.
Hanging rpms (bad idle) can just be your exhaust valves are too tight.

Quote from: ace50 on July 09, 2014, 05:53:21 AM
Quickly scanned thread, didn't see you mention if you have checked or know where your valves are set at.
Hanging rpms (bad idle) can just be your exhaust valves are too tight.

Hello ace50,

No, I do not know what are my valves are set at.

Is this the correct video to follow to inspect the valves?
https://www.youtube.com/watch?v=j4vRm9xADa8

That'll work!

Hello!

I just check my valve clearance and here are the results:

Left Exhaust
Current Shim Size: 2.62mm
Clearance: I was not able to determine the clearance as my smallest feeler gauge size at 0.02mm would not fit.

Right Exhaust
Currect Shim Size: 2.67mm
Clearance: 0.04mm
New Shim Size should be:
0.10-0.04= 0.06 ----- 2.67mm-0.06=2.61 (2.60mm)

*I got the 0.10 clearance from referring to this video by BaltimoreGS:
https://www.youtube.com/watch?v=5J19aNdXV08#t=630

Left Intake
Current Shim Size: 2.71mm
Clearance: I was not able to determine the clearance as my smallest feeler gauge size at 0.02mm would not fit.

Right Intake (In Spec)
Current Shim Size: 2.62mm
Clearance: 0.08mm

How do I determine what shim size I need to replace the Left Exhaust and Left Intake?

Should I follow this guide: http://gstwin.com/adjust_valves.htm and replace it with 0.05 thinner shim?

So the new Left Exhaust Shim Size would be: 2.62-0.05=2.57mm (2.50mm) and Left Intake Shim Size would be: 2.71-0.05=2.66mm (2.60mm)?

Also just to clarify should the camshaft notches be facing outwards when I am done? And not facing towards each other?

Thank you!

Try swapping the left and right intake shims since you couldn't get a measurement with the 2.70 shim. You'll find out if you need a 2.60 or a 2.65 shim that way. Just remember not to turn the camshafts with no shims under them.....

Quote from: Big Rich on July 09, 2014, 06:42:12 PM
Try swapping the left and right intake shims since you couldn't get a measurement with the 2.70 shim. You'll find out if you need a 2.60 or a 2.65 shim that way. Just remember not to turn the camshafts with no shims under them.....

Excellent idea, Big Rich! I just did that and here are the results

Left Intake
Current Shim Size: 2.62mm (Swap from Right Intake)
Clearance: 0.10
New Shim Size should be: 2.62+0.08=2.70mm? 

I guess I can't check the Left Exhaust clearance without an extra shim in hand

Do you guys think my calculations is correct for the three new shims?