Noobie help... Fast Idle

[ponchopirate]

I took my '89 GS 500 on its first ride since I brought it back from the used bike shop and everything appeared to be fine.  It warmed up quickly, needing choke for only about 30sec before it would idle around 1200rpm without choke.  I headed out for a nearby parking lot to practice and when I got there I noticed the bike was idling at 4000rpm.  I turned around and headed back home.  I shut the bike off and then fired it up again, same thing, 4000rpm.  I checked to make sure the choke was off and that the throttle was closed all the way.  I've never done any motorcycle maintenance before but I've got the Clymer manual in the mail.  Any advice on what to look into?  Thanks!

[Jared]

Hanging rpms at idle means there is a lean condition.  Did they do any carb work on the bike? Aftermarket exhaust?

Check for vacuum leaks (Spray wd-40 around the intake boots (between carb and engine) and see if the idle changes... also check your vacuum lines to see if they need replacing. It's an 89 so if it has alot of original rubber parts -you can almost bet they need replacing.

The 94 I am working on- It's intake boots shattered pretty much from age/mileage when I went to remove the carbs the other day.

[ponchopirate]

Thanks for the info.
When I picked it up from the shop they said they had to do some carb work.  One needed cleaning and another was "missing a part."  No aftermarket exhaust or jetting.  I test rode it and didn't experience any of the problems I'm having now.  Even when it first starts up and is idling in the proper range (1200rpm) if I rev the engine, it drops rpms very slowly.

[Jared]

Well you can give them the option of fixing it ( since it's not right .) -but will you get the same unsatisfactory job they did in the first place...(?)

OR....When you get your clymer manual...try your hand at fixing it yourself. If you're handy and  decent at fixing things carbs aren't TOO bad....

Likely they didn't clean something well or left an oring out ( carb tops have a little oring where the vacuum ports for the fuel petcock is (also used for synching carbs)....It might be something really simple.

I mean if you just picked it up and it's running bad- they should fix it. Unless of course you get a tail light warranty with the bike ( The warranty expires when they see your tail light leaving the parking lot...)...

Good luck....there's lots of info on carbs on this site....both in the forumns and in the site itself.....

[pantablo]

Ultimately you need to rejet your carbs. They come lean from the factory. One thing you can do in the interim is to lower the idle speed when its warm and at 4k. Lower it to about 2k or less when warm. This will make the bike want to warm up longer though when you first start it.

here's a good tutorial with photos on how to rejet the carbs:
http://www.angelfire.com/mt2/mikesgs500/rejetting/

another can be found in the maintenance link in the pull down menu (located in upper right corner of this page).

[ponchopirate]

Thanks for the info.  The clymer should arrive any day now.  I guess I've got my work cut out for me.  Technically I have a 30 day warranty,  but they managed to screw it up the first time, and being over fifty miles away, I don't really think it's worth hauling it back to the dealer.  Now I know this is a dumb question, but the idle adjustment is hanging out the bottom of the carbs, right?  I'm still learning.  Thanks.

[Kerry]

the idle adjustment is hanging out the bottom of the carbs, right?

Yep.

[ponchopirate]

Argh...  turned the screw and got the idle down, but it just shoots right up and stays there after I give it throttle.  Looks like I don't even get a temporary fix.  Oh well, I'll pull the carbs tomorrow.  Trial by fire.

[ponchopirate]

I looked over the site on rejetting and I'm up to the task.  However, can I rejet my carbs and still keep the stock exhaust on the bike?  My cash is tight, but I have to solve this problem.