Also check to make sure both cylinders are running.  If one is hot and the other is cooler then you need to change spark pluges.  Its just a quick thought.

(not my image)


The flower-shaped screw labeled "1" in that picture is the idle adjustment. Tightening it will increase idle speed - loosening will reduce. Yours will look slightly different and is plastic from what I can tell in your pics. One full turn should grant you about 200RPM, give or take. It's not super critical that it be exactly a certain number, just that it sounds like it's idling smoothly and that it isn't above 1500.

Also, did you happen to sync the carbs? Normally, most people recommend that you sync the carbs after you do anything to them. It's not a big deal. It's just a little time consuming making the tool and taking the tank back off.

I adjusted the idle a little higher and that resulted in the engine racing a little.  While riding it it accelerates a little when I'm not turning the throttle.  So I don't think that is the solution.

This is the same problem I had prior to cleaning the carbs, so I don't think it was caused by anything I did. 

As far warm up, I warm it up the way you describe.  It seems to warm up just fine.  Like I said the engine sounds good and strong at idle and revving and while riding.  It's just when I slow to a stop that a problem occurs.

I changed the spark plugs when I cleaned the carbs.

No I didn't sync the carbs.  I'll put that on my list of things to do, but would the carbs being out of sync cause the engine to die?

I'll feel the engine next time I run it to try and see if both cylinders are firing.

Thanks again for all the input.

Oh yeah, why shouldn't I leave the fuel petcock on PRI?  What should I leave it on, on or reserve?

thanks

Quote from: Karl with a K on February 08, 2012, 03:55:27 PM
Oh yeah, why shouldn't I leave the fuel petcock on PRI?  What should I leave it on, on or reserve?

thanks

PRI or "PRIME" bypasses the vacuum operation. The GS500's are known to have somewhat weak float needles. What can result is fuel flooding into your airbox/intake. Both "ON" and "RES" are operated by the vacuum. In other words, the petcock is "off" when the bike is not running. Suction from the carb causes the petcock to turn "ON" in both RES and "ON".

Quote from: Karl with a K on February 08, 2012, 03:34:46 PM
I adjusted the idle a little higher and that resulted in the engine racing a little.  While riding it it accelerates a little when I'm not turning the throttle.  So I don't think that is the solution.

This is the same problem I had prior to cleaning the carbs, so I don't think it was caused by anything I did. 

As far warm up, I warm it up the way you describe.  It seems to warm up just fine.  Like I said the engine sounds good and strong at idle and revving and while riding.  It's just when I slow to a stop that a problem occurs.

I changed the spark plugs when I cleaned the carbs.

No I didn't sync the carbs.  I'll put that on my list of things to do, but would the carbs being out of sync cause the engine to die?

I'll feel the engine next time I run it to try and see if both cylinders are firing.

Thanks again for all the input.

So what happened was you turned the screw a little and all of a sudden the RPM jumped way up?

If that's the case, you've got a vacuum leak. Someone else will need to comment on the common places for vacuum leaks on the newer gen carbs since I'm not as well versed with them as I am the older model. A good place to start looking, however, is the boots that connect the carbs to the motor. Also check the tightness of the clamps.

You could also check the diaframs in the carbs.  They are easy to pinch when you are putting it back together.  Good on you for changing plugs.  Dont worry you are narrowning it down and we will help, just keep at it.  The more info you give us the more suggestions we may have.  Keep going.

I also have a new air filter waiting to be picked up at the dealer.  I know that may not be a contributor to the problem, but the old one looks dirty and it couldn't hurt to replace it.

The rubber diaphrams looked good when I had the carbs disassembled.  Taking the advice from this board I looked carefully for any small holes or tears and I didn't see any.  They were soft and pliable, not dried out at all.  The carbs looked really clean and in good shape overall. 

I wonder if soapy water sprayed around the carb boots where they meet the engine would reveal a vacuum leak?  Any other suggestions for trouble shooting that?

Quote from: Karl with a K on February 08, 2012, 08:18:13 PM
I also have a new air filter waiting to be picked up at the dealer.  I know that may not be a contributor to the problem, but the old one looks dirty and it couldn't hurt to replace it.

The rubber diaphrams looked good when I had the carbs disassembled.  Taking the advice from this board I looked carefully for any small holes or tears and I didn't see any.  They were soft and pliable, not dried out at all.  The carbs looked really clean and in good shape overall. 

I wonder if soapy water sprayed around the carb boots where they meet the engine would reveal a vacuum leak?  Any other suggestions for trouble shooting that?

WD-40 or starting fluid is the preferred method of detecting leaks around the boots and carbs. WD-40 won't evaporate like starting fluid but isn't as volatile. Take your pick. Personally, I'm a little weary of spraying something as flammable as starting fluid around a hot motor but I guess it'll be okay. Many, many people have used this method successfully. The idea is that when it sucks the stuff in, it'll cause the idle to increase.

Quote from: Kijona on February 08, 2012, 04:20:03 PM
Someone else will need to comment on the common places for vacuum leaks on the newer gen carbs

That's cause you've only owned a GS for like a month

Ok, some riding buddies have suggested that the Air/Fuel Mix screw could be a culprit.  Since there are plugs sealing them in, I never removed the screw to clean it.

Tight Valves could be a culprit?

Out of sync carbs?

Ok, so my plan of attact is as follows:

Install new air filter.

Remove the carbs again.  Remove the air/'fuel screw and clean it and all it's passages as best I can.

I'm considering going with a stage 1 jet kit since I'm going this far anyway.

Before buttoning it all back up I'll check the valves.  If they are out of spec I'll adjust them.

Lastly I'll sync the carbs.

I think that will cover all the bases.  What could possibly go wrong?

Thanks for the interest in this thread and all the advice.  I will keep you all posted.

I'm off to search the net for a shop manual.

Karl, I have what I assume is the shop manual, and a supplement for the F model.  PM me your email and I'll send it to you.

Also, I just want to say that this is a freaking awesome thread.  Everyone involved should be proud. 

Quote from: Karl with a K on February 10, 2012, 09:05:17 PM
Ok, some riding buddies have suggested that the Air/Fuel Mix screw could be a culprit.  Since there are plugs sealing them in, I never removed the screw to clean it.

Tight Valves could be a culprit?

Out of sync carbs?

Ok, so my plan of attact is as follows:

Install new air filter.

Remove the carbs again.  Remove the air/'fuel screw and clean it and all it's passages as best I can.

I'm considering going with a stage 1 jet kit since I'm going this far anyway.

Before buttoning it all back up I'll check the valves.  If they are out of spec I'll adjust them.

Lastly I'll sync the carbs.

I think that will cover all the bases.  What could possibly go wrong?

Thanks for the interest in this thread and all the advice.  I will keep you all posted.

I'm off to search the net for a shop manual.

GSTwins sells a shop manual. $20. Other methods are available but most of us here frown upon them. We understand that not everyone is made of money, though.

Checking the valves?  It's a good idea anyway so why the hell not? It sure is a pain to remove all that crap, so, might as well git'r'done.

Now, about jetting. You'll need this information: http://wiki.gstwins.com/index.php?n=Upgrades.Rejetting

Buying a "kit" is going to cost you a lot more than it should. I've seen jets for our carbs for as little as $4 a piece. With that in mind, even if you replaced all 6 jets, that would only be a total of $24 - much cheaper than a jet kit. That wiki should have the sources for you. You can also contact The Buddha or Adidasguy to see if either of them have any extra jets for you.

Onto drilling the mixture screw caps.



I'm sure you probably already knew which caps to drill but I just wanted to be clear. There are a few pics of people's carbs floating around where they mistakenly drilled the caps below those. Needless to say, drilling those lower caps will ruin your day (and your carburetors). The method of removal is simple...drill the hole slightly bigger and then insert a sheetrock screw and pull/bend/whatever to remove them. Do be gentle with them, though. Also, note that there are springs beneath the mixture screws - very weak springs but springs nonetheless. Just be sure you don't let anything go flying! There's an o-ring in there too, which might be the cause of your dilemma.

Putting up links to the PDF's well technically not legal. But, if someone is having a real problem getting a hold of one weather access or money is not frowned upon unless it has changed recently 

Karl welcome to the board. I would suggest checking valve clearances as well. I had these issues with Flick and assumed it couldn't be the valves due to maintenance plan boy was I wrong. I ended up with a burnt valve! So, try to check everything as you can!

mary

Hey Karl, my name is Karl too. Now that that's out of the way, I'd recommend that you buy some socket head cap screws to replace all the JIS screws on the carburetors. Doing so makes future disassembly much easier. Really I just wanted to post because we share our first name.

4 x M5x12mm
10 x M4x10mm

Quote from: k.rollin on February 12, 2012, 02:45:45 AM
Hey Karl, my name is Karl too. Now that that's out of the way, I'd recommend that you buy some socket head cap screws to replace all the JIS screws on the carburetors. Doing so makes future disassembly much easier. Really I just wanted to post because we share our first name.

4 x M5x12mm
10 x M4x10mm

Earlier on in this thread I recommended this to him but I think he wants to keep it stock. 

I didn't replace the JIS screws partly due to laziness and partly due to the impact driver worked so well that the heads weren't damaged.  Lowe's doesn't carry the screws I need so I'll have to find a real hardware store.

I'll probably replace them this time around.

Good info on the jets.  I'll be shopping.

Work is going to interfere with my wrenching this week

I don't expect to get into this until next weekend.

I'll keep you guys and girls posted

Quote from: Karl with a K on February 12, 2012, 10:44:53 PM
I didn't replace the JIS screws partly due to laziness and partly due to the impact driver worked so well that the heads weren't damaged.  Lowe's doesn't carry the screws I need so I'll have to find a real hardware store.

I'll probably replace them this time around.

Good info on the jets.  I'll be shopping.

Work is going to interfere with my wrenching this week

I don't expect to get into this until next weekend.

I'll keep you guys and girls posted

Shoot me a private message with your address and I'll send you a set for free.

You have mail.