Some history - bike has new major tuneup - plugs, wires, valve adjustment.  Carbs have been thoroughly cleaned on the bike and work great, except for idle.  Bike has 21,000 miles and runs great, gets great mileage and will really move out, if pushed.  There was a hesitation right off idle but the can of sea foam took care of that.

The idle is, well, weird.  It seems to rumble.  The tach cycles, running slower then faster in regular rithum.  It seems to have a vacuum leak and, if it was a car, that's what I'd be checking. 

I cleaned the vacuum valve that lets air into the exhaust.  Of everything I see, that seems to be the one possibility that could cause a cycling, rumbling miss.  Are those things known to go bad?  What happens if you just disconnect it, and plug the vacuum line?

I'll bet somebody that has had a lot of experience with the concours can tell me what's wrong right away.  I sure would appreciate it.

Oh, and can I get a brighter headlight bulb?  What bulb should I buy?

I don't claim to be a guru. 

If a shop did the major tune up and the bike doesn't run right, I'd think about taking it back to them.

If there was a slight hesitation after the carb cleaning, and a can of sea foam seemed to take care of it, then I would question how thorough the carbs were cleaned and maybe they need to be cleaned again.

I'm guessing you bought this bike used.

Did the bike exhibit this trait prior to the tune up and did that make any diff?

I'd make sure all the vac lines are attached and in good condition, as well as checking the carb to boot clamps.

You didn't say if the carbs had been synced.

What year is the bike because if older you could have a coil pickup problem.  I did, where one of the wires was intermittently losing contact at various rpms.

I'm not sure what you mean by vacuum valve.  I'm not aware of anything that lets air into the exhaust.

Brighter headlight bulb - I'm not sure if there is a Silverstar option but I heard those are good but the life is shorter.  There is another option to go to a higher wattage bulb but I believe to be safe you will want to replace the headlight wiring harness or something to prevent it from melting.  I believe Murphs Kits has a kit. http://www.murphskits.com/catalog/product_info.php?cPath=1_28&products_id=102

  It's possible to remove the whole vacuum system with these.

         http://www.zggtr.org/index.php?topic=99.msg595#msg595

   gets rid of a crap under the tank.

Hey Mettler1 - thanks for replying.

No shop works on my bike.  I almost got killed once 'cause of making that mistake.  NEVER AGAIN!  All I get done now is tires mounted, 'cause I don't have a balancer, and that scares me to death!

The carbs were cleaned on the bike with different carb cleaning products.  If I absolutely have to I will rebuild them next spring - not much sense in doing that at the end of the season.  I am waiting to get everything else ironed out first, then I will synch the carbs.

Yeah, it was doing this from the start and it has gotten better, but not gone away.

It's a 2001

The thing is called the PAIR system.  http://i247.photobucket.com/albums/gg136/hoggone/Concours%20pictures/027_zps4bb1662d.jpg  - A pic of where it goes, but this guy removed it.

I found the headlight info in another post.

Where was the pickup wire losing contact?  At the pickup?  Oh, I hope not, cause all that plastic would have to come off again...  I have thought of finding and cleaning the place where the pickup wires plug in but have yet to do so.  Do you know where that is?

  Wanna know about carbs on the Concours?  Steve in Sunny Florida has gotten them down pat.

   Here is his website for some good reading.

          https://sites.google.com/site/shoodabenengineering/

             https://sites.google.com/site/shoodabenengineering/intake-and-exhaust

  Also forgot to add about hydrolock  and overflow tubes on the carb bowls. Good reading and could save you a destroyed engine.  Info also on Steve's website.

I do believe that you can get a used set of bowls from the voyager 12 which are a direct replacement, and they have the overflow tubes.

  Yes you can if you can find them. I never looked as I already have Steve's but have heard the kind of rare. If you find a source, grab'em!

  I'm assuming you mean the pickup wire for the tach. My tach works fine so I never had to look for it.

   Idle is the Concours weak spot from idle (1100 rpm) to about 3000 rpm. You will find that on Steve's website also.

No, the ignition pickups.  I can see the wires coming from the left side of the motor but difficult to see where they go?

No, the ignition pickups.  I can see the wires coming from the left side of the motor but difficult to see where they go?

yes the pickups are behind that cover. I assume they were for ignition only but you are right as they probably go to the tach also.

Yeah, where were the wires loose on those pickups?

  I assume that if there were loose wires in there in would also effect ignition also. Last time I was in there all I found was the pickups and the wires went directly out. When it comes to electricity I only know the pain when I grab the wrong one!!

  As far as a brighter bulb I use an 80/100 watt with Murphs' headlight relay kit.uses heavier wire and plug for less resistance and heat.

  I mentioned "hydrolock" early and don't know if you have heard of it but is a video that explains it.

       Concours ZG1000 hydrolock rod test

Obviously there could be a few factors to a cycling idle, but honestly the factory idle isn't anything to write home about from the git-go. The pilot air screws are adjusted very lean, and then capped to be "tamper proof" . Even on totally proper and clean carbs, the idle will be better if the caps are drilled off and the pilots screws set at 2 turns.

Syncing is also important, but needs to be done after a valve adjustment. you may have a tight intake valve causing low vacuum on a given cylinder, and of course that's going to show up as a poor sync and even worse idle / low speed operation. HTH, steve

No, the ignition pickups.  I can see the wires coming from the left side of the motor but difficult to see where they go?

The ignition pickups behind the left side engine cover.  There is a gapping spec too, which is easy to check.  I had narrowed down my choices for a running issue I had and when I adjusted the gap it seemed to go away, only to return later.  I figured they got out of adjustment again but checking them revealed not.  I took a shot and ordered new coil pickups.  Very easy install.  Connection, as I recall, is up towards the seat/tank. 

When I had the old unit off, I figured I'd cut it open to see exactly what was inside that might be causing my problem.  When I started hacksawing on it, one of the wires came out of the pickup.  I thought hmm, I may as well pull the other out but tugging on it couldn't budge it so there was no way that first wire should have come out so easy.  Like $115 for new pickup.  This was on an 87 model and I replaced it about 3 years ago with around 70,000 miles.

I'd suspect the carbs need to be pulled and cleaned.  I've never had much luck with the add-to-gas carb cleaners.  I once soaked dirty carb parts in straight STP add-to-gas cleaner (overnight) and figured that would clean them right up and it barely touched them.  I bought the commercial soak (Chem-something) and it cleaned the parts in about 20 minutes.

  If you're still trying to chase down a vacuum leak, a little shot of carb cleaner around the carb boots & carb assy while its' running, may help pinpoint it a little easier.

Hey Summit, Deans, thanks for replying.

Pulled the tank and checked the vacuum to the aspirator valve and the tank petcock.  No leakage there so I left it alone.  I was able to get a long phillips onto 3 of the 4 carb-side clamps and the right two tightened down a bit - the outside one quite a bit.  Maybe that will help. 

Found the intermediate plug (right where the tank bolts on) and the plug on the ecu.  Resistance to the pickup coils is within spec.  Cleaned the contacts and applied dielectric grease as I reassembled it. 

I'll take it out this evening when it cools off.  Maybe it's fixed.  I started it and it might have sounded better - won't be able to really tell until it's running at operating temp.

Thanks for the tips - we'll figure this out .)

 
'The carbs were cleaned on the bike with different carb cleaning products.'

I am not going to say one word..not one.