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Main Area => General GS500 Discussion => Topic started by: Chilly Willy on October 10, 2006, 06:29:38 PM

Title: Racing engine at intersections, stops, etc.
Post by: Chilly Willy on October 10, 2006, 06:29:38 PM
Hi all,

I've had this happen a couple of times now and it's starting to freak me out a little.  I'll come to a stop at an intersection, pull in the clutch, roll off the throttle, and the engine will rev up all by itself.  I've even taken my hand completely off the throttle while this is happening.  Each time, I just hit the engine kill switch, started back up again, and rode away just fine.

What's going on?

Thanks,

Chilly Willy
Title: Re: Racing engine at intersections, stops, etc.
Post by: rangerbrown on October 10, 2006, 06:40:32 PM
choke is sticking sounds like
Title: Re: Racing engine at intersections, stops, etc.
Post by: Chilly Willy on October 10, 2006, 06:43:21 PM
Cool.  So how do I fix this?

Chilly Willy
Title: Re: Racing engine at intersections, stops, etc.
Post by: rangerbrown on October 10, 2006, 06:46:15 PM
remove seat
remove gas tank
and check cable all the way down to the carbs.

if cable is find then check the carb linkage on carb (remove carb)
Title: Re: Racing engine at intersections, stops, etc.
Post by: Chris_B on October 10, 2006, 07:30:20 PM
Sounds more like its running way lean. Check for vaccuum leaks, your mixture screws may need adjusting, or your carbs could be dirty. Or the choke is sticking, but I dont think it would be back to normal after shutting it down and starting it back up if it was the choke sticking/not closing fully.
Title: Re: Racing engine at intersections, stops, etc.
Post by: Turd Ferguson on October 10, 2006, 08:54:11 PM
Quote from: Chris_B on October 10, 2006, 07:30:20 PM
Sounds more like its running way lean. Check for vaccuum leaks, your mixture screws may need adjusting, or your carbs could be dirty. Or the choke is sticking, but I dont think it would be back to normal after shutting it down and starting it back up if it was the choke sticking/not closing fully.

+1

My vote is for lean.

-Turd.
Title: Re: Racing engine at intersections, stops, etc.
Post by: Chilly Willy on October 10, 2006, 08:55:31 PM
How do I fix lean?

Chilly Willy
Title: Re: Racing engine at intersections, stops, etc.
Post by: Chris_B on October 10, 2006, 09:19:00 PM
Check to make sure the vaccuum line coming off the left carb isnt cracked or poor fitting, make sure the boots arent cracked or dried out, and make sure they form a good seal around the carb and onto the cylinder head. The pilot jets are pretty small and can be clogged fairly easily, taking the carbs off and cleaning them is never a bad idea. Adjusting the mixture screw may fix the problem, in makes it leaner, out makes it richer.
Title: Re: Racing engine at intersections, stops, etc.
Post by: thirdman on October 10, 2006, 10:09:33 PM
I had the exact same thing happen to me, and adjusting the mix screws out (richer) fixed it right up.  :thumb:
Title: Re: Racing engine at intersections, stops, etc.
Post by: Chilly Willy on October 10, 2006, 10:11:17 PM
Thanks all,

I'll give it a look and a try. 

Chilly Willy
Title: Re: Racing engine at intersections, stops, etc.
Post by: Chilly Willy on October 11, 2006, 08:33:24 AM
Quote from: thirdman on October 10, 2006, 10:09:33 PM
I had the exact same thing happen to me, and adjusting the mix screws out (richer) fixed it right up.  :thumb:

Can I adjust the mix screws without removing the carb from the bike (i.e. how complicated is this process)?

Thanks,

Chilly Willy
Title: Re: Racing engine at intersections, stops, etc.
Post by: mjn12 on October 11, 2006, 08:47:39 AM
Yep

I use a small flathead bit that you would normally slide into one of those magnetic screwdriver handles (spinner handle, whatever you want to call it). Don't try and put it in any kind of handle, just hold it with your fingers.   It takes a little feeling around and you have to pay attention to the oreintation of the bit to determine how much you are rotating the screw. 
Title: Re: Racing engine at intersections, stops, etc.
Post by: Chilly Willy on October 11, 2006, 09:03:51 AM
Cool--how much should I rotate it and when do I know if I've gone too far?  How do I tell when it's "just right"?

Thanks,

Chilly Willy
Title: Re: Racing engine at intersections, stops, etc.
Post by: Mandres on October 11, 2006, 09:40:47 AM
Quote from: Chilly Willy on October 11, 2006, 08:33:24 AM
Quote from: thirdman on October 10, 2006, 10:09:33 PM
I had the exact same thing happen to me, and adjusting the mix screws out (richer) fixed it right up.  :thumb:

Can I adjust the mix screws without removing the carb from the bike (i.e. how complicated is this process)?

Thanks,

Chilly Willy

It depends on whether the brass caps that come stock covering the mixture screws have been removed or not.  If the previous owner removed the caps you can adjust the carbs on the bike.  If the caps are still there you'll have to pull the carbs to drill them out.
Title: Re: Racing engine at intersections, stops, etc.
Post by: FearedGS500 on October 11, 2006, 10:09:27 AM
chilly i thought the bike was new ? are you out side of the warrenty date ? if not i'd talk to the stealer and see what they say
Title: Re: Racing engine at intersections, stops, etc.
Post by: Chilly Willy on October 11, 2006, 10:34:52 AM
Nope, the bike is just new to me.  It's a 94 with 10 k miles when I bought it. 

Chilly Willy
Title: Re: Racing engine at intersections, stops, etc.
Post by: scratch on October 11, 2006, 11:00:59 AM
Here's a picture with the brass caps still installed.  Once you take them out, leave 'em out.
Now, for adjusting, I'd gently screw them in just until they seat lightly, then back them out two full turns and half a turn, or three whole turns, depending on your taste.
(http://www.bbburma.net/MiscFotos/DSCF2431_Idle_Drain_Mixture_Screws.jpg)
Title: Re: Racing engine at intersections, stops, etc.
Post by: Chilly Willy on October 11, 2006, 11:15:00 AM
Excellent, thank you!  How do I drill out the brass cap in such a way that I don't damage the screw underneath?  What size drill bit / what depth?  Is this tricky or would I be better off removing the carb from the bike before trying it?

Thanks,

Chilly Willy
Title: Re: Racing engine at intersections, stops, etc.
Post by: scratch on October 11, 2006, 11:18:03 AM
You will have to remove the carbs, so you can turn them upside down.  The cap is about 3 or 4mm thick, and there's maybe a mm of space before the screw.  Just drill til you break through and let your reflexes release the trigger.  Wear eye protection.
Title: Re: Racing engine at intersections, stops, etc.
Post by: RVertigo on October 11, 2006, 11:52:44 AM
Did this issue JUST start?

'cause you may have pinched a hose or something.
Title: Re: Racing engine at intersections, stops, etc.
Post by: mjn12 on October 11, 2006, 12:45:56 PM
wait a sec, I though willy was on a 94? Those didn't have brass caps did they?

When did they start installing those?  Maybe I'm just confused.
Title: Re: Racing engine at intersections, stops, etc.
Post by: Chilly Willy on October 11, 2006, 12:51:44 PM
Yep, I've got the brass caps--I went home and checked at lunch today.  The issue has recently started, happening on my last two rides.  I don't have a whole lot of time logged in on the bike yet, but it seems like a recent issue.

Chilly Willy
Title: Re: Racing engine at intersections, stops, etc.
Post by: scratch on October 11, 2006, 02:32:53 PM
Brass caps have been installed for as long as Federal Emmission Standards have been in place.  I'd say since before 1975.
Title: Re: Racing engine at intersections, stops, etc.
Post by: bobmelvin on October 12, 2006, 06:37:23 AM
I had something similar happen after I had ridden for 15 minutes or so, the rpms would shoot to 3000 to 5000. Adjusted the idle, and it went away. The same problem at stops, though. The bike was new to me, and I had a couple of scary starts before I figured out what was happening. Just a thought. It may or may not apply. It was a 5 minute fix, though, and no problems since.

Cheers
Title: Re: Racing engine at intersections, stops, etc.
Post by: Chilly Willy on October 12, 2006, 07:29:51 AM
Thanks Bob,

The idle was off when I bought the bike.  The RPMs were way too low and the bike would not start moving unless I gave it a lot of throttle.  I adjusted it right after I bought it and now the RPMs sit at the recommended idle spot (1200-1500).

Chilly