Ok my 99 gs500e runs like $hit, its only getting like 30mpg and it back fires like crazy. I think its kinda obvious that its running rich, but when i went to check the mixture screws they still had the factory caps on them (could the still be lose?) so my brother told me it probably needs to have the carbs synched. So i searched on the forums for carb synching and all i found were posts asking how to make a homemade manometer and few showing exactly that. But, i havent found one that shows how to use that tool...could someone please show me how to synch my carbs

shaZam! actually im only getting like 28mpg

The backfiring sounds more suspicious of something other than just carb syncing. I would be more concerned about valve adjustment and timing chain tension first.

I don't remember a GS How To thread about syncing. Most of us have a Clymer or Haynes manual. Both have nice How To regarding the carbs and syncing them up. I remember a thread about the Motion Pro carb sync tool. Maybe it was one with Kerry?

I'm just rebuilding two sets now and will soon enough be having to do it myself. So maybe it would be a good time for such a thing? Who knows? I might get another FAQ posting.

so should i just take it to my local bike mechanic and have him work on it...how much do you think i should expect to pay for a full tune up. Valve and carb work.

BTW the bike has over 11k miles on it and going by the condition its in i doubt it has ever seen the inside of a shop since it was bought...so it could have all sorts of problems

Hmmmm. Do you like riding more than wrenching? This GS sounds like a many of them we hear about - poorly maintained.

They actually are a great bike to learn to wrench on. Do you have a place to do this and tools to do it with?

The shop can fix it, but your pocket book will take a beating if it is time consuming to do it.

i dont mind wrenching...i mean i got it running in the first place, i bought it on ebay not running. its just that i think the valve adjusting is above my skill level, that and i dont have the tools for it.

Ah well, a GSer after my own heart! I bought mine not running on ebay also. Check out my webpage (look in my signature at the bottom of the posts).

I haven't done my valves yet, but we have a great video/valve adjustment kit running around the GS world. I have no idea who has it now, but if you've gone this far, why stop now?

Check out Kerry's page (click me) also. It has tons of GS stuff on it. We haven't heard from Kerry in months, but his page is still up.

^ umm are you sure the page is still up...cuz that link isnt working. BTW i think i can do the valve adjustment if i really put my mind to it, but id like to do the carb synching while i have the bike apart. I heard there is a way to "visually" synch the carbs if they are completely off the bike...how do i do that?

Quote from: cell_491 on March 12, 2006, 07:24:01 PM
^ umm are you sure the page is still up...cuz that link isnt working.

Kerry's page is still working...at least for me. I even refreshed it. He doesn't have carb sync information there though. He did a video and put it on V-CD. It is somewhere in the GS community. There is a thread about it in this section.

Quote from: starwalt on March 12, 2006, 07:32:04 PM

Quote from: cell_491 on March 12, 2006, 07:24:01 PM
^ umm are you sure the page is still up...cuz that link isnt working.

Kerry's page is still working...at least for me. I even refreshed it. He doesn't have carb sync information there though. He did a video and put it on V-CD. It is somewhere in the GS community. There is a thread about it in this section.

thats strange...its not working on firefox or IE. Also i have a question... once i removed the head cover breather a piece of steel wool (well sorta) popped out... does it fit on the side closer to the vacuum tube or what? ALso to remove the haed cover do i need to remove the two bolts that were underneath the head cover breather?

The link to Kerry's homepage just worked for me...

You can download Kerry's Valve Adjustment How-To video from this link:

http://www.jackardisana.com/gs500/GS500ValveAdjustment.wmv

Just right-click that link and choose "Save Target As..." (or "Save Link Target As...", or whatever option is available with your browser). The video is BIG, more than HALF-A-GIG (550 MB), so be prepared for a LONG download, unless you have a broadband connection...

Quote from: cell_491 on March 12, 2006, 07:46:09 PM
Also i have a question... once i removed the head cover breather a piece of steel wool (well sorta) popped out... does it fit on the side closer to the vacuum tube or what?

The mesh filter should cover the exit port the tube uses.

QuoteALso to remove the haed cover do i need to remove the two bolts that were underneath the head cover breather?

The two bolts/screws under the breather cover are for the cam chain guide under the valve cover.  There are six (6) Allen bolts that hold the valve cover on the engine head. All are metric, of course.

I commend your wrenching spirit, but a Haynes or Clymer manual will do you wonders! It will also be a great item to include with the GS if you ever sell it. Hopefully you will never want to.

i had all the bolts off the head cover it just needed to be persuaded to pop off...that persuasion came in the form of a hammer.

pretty cool video...however i still would like to know how to visually synch the carbs if its possible

you 'visually' synch the carbs by looking at the throttle butterfly plates and adjusting the screw so the same amount of light shows behind each plate.  That being said, I don't like this method.  It's imprecise, and doesn't account for airflow differences through each carb.  It can give you a ballpark setting after seperating the carbs but you really should use the proper method.

The proper way to synch the carbs is with the vacuum test.  You hook up some kind of vacuum-measuring device to the port on the top of each carb and start the engine.  Let it warm up fully and adjust the idle to ~1750 rps.  Monitor the readings from the tool while turning the synch screw.  Set the screw so that each carb pulls the same amount of vacuum. 

For pics of a homemade manometer check this thread and others by the same author:

http://gstwins.com/gsboard/index.php?topic=3521.0

-M

ok, the very best way to sych carbs with no special tools, firstly ensure that the carbs are free from each other, so any adjustment you do on one carb does not upset the other, then on the first carb wind the throttle stop up high, disconnect the spark plug lead from the other cylinder, then fire it up on one cylinder. Adjust the throttle stop down untill the motor just adles without stalling, stop motor reconnect plug lead and disconnect the other plug lead, do the same as the first carb. Then reconnect both plug leads fire up on two cylinders, it will run at reasonably high revs, and adjust both throttle stops evenly to get a good idle, lock the carbs together, carbs are perfectly balanced, thats the way we used to do it on earlier twins, I am thinking that it would work on the GS.

robinm1's method sounds interesting, but it probably won't work with the Mikuni carbs on the GS.

The "slave" carb has no throttle stop. If separated from the "master", the slave throttle just flops around.

Interesting method though. A rookie might be tempted pull the plug lead while the engine is running. The rookie would only do it once. 

It could work if you first set the master carb with the idle screw, then the slave with the synch screw.

I don't feel too bad about synching by eye. I don't go for the light gap, however, I adjust the butterflies to identical position over the small holes that are in the region of their edge when they are closed. In a way I trust this more than a cheap pressure gauge whose reading depends very much on the attenuation of the input pressure line (you have to throttle this down to almost nothing; else the needles flowp around like mad.)

I synched my carbs similarly to robinm1's method to get it running decently until I can get the valves adjusted. I simply unhooked the spark plug wire on one cylinder and hooked it to a spark tester to keep from frying the ignition system.  I then went back and forth adjusted the synch screw until the carbs idled at the same speed individually.  It got my left cylinder running fairly well. 

I also built the homemade differential manometer.  It seems to work okay, but something seemed to be causing balancing issues.  They will be balanced at low rpms, but then the right cylinder will increase vacuum much more than the left with just a bit of throttle input.  I am going to adjust my valves before trying this method again.