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Main Area => General GS500 Discussion => Topic started by: iv76erson03 on April 28, 2012, 09:14:42 PM

Title: Please help troubleshoot my poor gas mileage
Post by: iv76erson03 on April 28, 2012, 09:14:42 PM
So I quit using fuelly last year and I wasn't keeping track of my mpgs, but I started again cause I got a 17t sprocket and wanted to see if it made a difference. Last couple fill ups, I'm getting 45, which is much lower than the 56-59 I always got before. The bike is a stock 2004.

Symptoms which may or may not be relevant.
-dropped the bike pretty good last fall on the right side.
-After riding hard for about a half hour, it idles at like 3,000. normally it will idle where it's supposed to
-Sometime it smells like gas, sometimes like hot oil. my nose isn't very good, so i don't know which, but i've never noticed it before
-feels more sluggish than normal. i recently put a 17t in it, so that may be it

My choke is all the way off, but the high idle makes it seem like its stuck. Maybe it's running rich somehow. I'm clueless, like to know what you all think.
Title: Re: Please help troubleshoot my poor gas mileage
Post by: slipperymongoose on April 28, 2012, 09:23:05 PM
Ok somethings going on with your carbs/fuel system. First up pull your carbs off and give em a good clean out, check out baltimoregs's video on how to. Next make sure all your fuel lines etc are running clear, while your carbs are off let some fuel out of your lines and see if its clear and not got crap in it. Give your air filter a good clean out, put it back together start her up n see.
Title: Re: Please help troubleshoot my poor gas mileage
Post by: Kijona on April 28, 2012, 09:44:20 PM
High/hanging idle is usually attributed to lean condition.

It's possible the cable for the choke got screwed up. Might check that the choke isn't engaging when you turn the handlebars.

If you rev the bike when it sticks at 3k RPM...does it take a while to idle-down?
Title: Re: Please help troubleshoot my poor gas mileage
Post by: jestercinti on April 29, 2012, 07:16:32 AM
^^ besides the above, also try this:

Tire pressure
Spark plugs
Air cleaner
Your use of the throttle (jackrabbit starts)
Carbs (already been covered)
Valve clearance

All attribute to gas mileage. When I had my Kawasaki Vulcan...was surprised to hear how bad my gas mileage was when my tires were 7-10 psi low from sitting all winter.
Title: Re: Please help troubleshoot my poor gas mileage
Post by: craigs449 on April 29, 2012, 08:21:51 AM
What is a good tire pressure to run with the stock BT45's?  I am also getting around 42-45 mpg with mine and I run 25ish PSI front and rear......
Title: Re: Please help troubleshoot my poor gas mileage
Post by: BaltimoreGS on April 29, 2012, 09:13:34 AM
Suzuki stock is 33psi front/41psi rear.

-Jessie
Title: Re: Please help troubleshoot my poor gas mileage
Post by: jestercinti on April 29, 2012, 12:31:06 PM
Quote from: BaltimoreGS on April 29, 2012, 09:13:34 AM
Suzuki stock is 33psi front/41psi rear.

-Jessie

Sometimes the simplest things are the answer.
Title: Re: Please help troubleshoot my poor gas mileage
Post by: Funderb on April 29, 2012, 01:06:21 PM
My in town and highway milage are vastly different. Even with stage 3 jets k&n and open exhaust:
in town: 42ish
highway: 62ish

It sounds a bit like a lean condition, you may have a leak somewhere that gets worse when very hot.
Title: Re: Please help troubleshoot my poor gas mileage
Post by: BaltimoreGS on April 29, 2012, 03:30:40 PM
Is the bike running on both cylinders?  Have you checked the valve clearances recently?  If an exhaust valve is not closing correctly raw fuel will be pushed out of the engine leading to a gas smell.

-Jessie
Title: Re: Please help troubleshoot my poor gas mileage
Post by: reload on April 30, 2012, 07:22:44 AM
it may be as something as simple as the carbs not sitting in their boots properly after the drop. take it apart and check it out.
Title: Re: Please help troubleshoot my poor gas mileage
Post by: SAFE-T on April 30, 2012, 08:46:01 AM
Highly doubtful it is the new sprocket ~ we put an 18tooth front sprocket on our 2007 GS500F and it never felt sluggish at all.
Title: Re: Please help troubleshoot my poor gas mileage
Post by: iv76erson03 on May 09, 2012, 05:23:36 AM
Quote from: Kijona on April 28, 2012, 09:44:20 PM
High/hanging idle is usually attributed to lean condition.

It's possible the cable for the choke got screwed up. Might check that the choke isn't engaging when you turn the handlebars.

If you rev the bike when it sticks at 3k RPM...does it take a while to idle-down?

Yes, it does hang when its warm. Haven't taken the thing apart yet, ill let you guys know what I find. :icon_idea:
Title: Re: Please help troubleshoot my poor gas mileage
Post by: Toogoofy317 on May 09, 2012, 08:55:21 AM
Check your valves!!!!!!!

I did what everyone else keep saying. Did the carbs at least 7 times. Gas mileage kept dropping and dropping until the valve finally burnt! Flick ended up with a top end rebuild. Reason I didn't check the valves to begin with had a maintenance plan it was supposed to have been done by "professionals" but wasn't. Flick also had the hanging idle when hot get to them valves!

Mary
Title: Re: Please help troubleshoot my poor gas mileage
Post by: HPP8140 on May 09, 2012, 03:42:13 PM
I'm having same hanging idle issue. checked valves, carbs still hanging/low idle and poor gas mileage.

Discovered it's my ignition coil. pulled right coil & bike could idle. pulled left coil & bike dies. Right coil was not working @ idle.
Title: Re: Please help troubleshoot my poor gas mileage
Post by: craigs449 on May 09, 2012, 04:27:04 PM
Quote from: HPP8140 on May 09, 2012, 03:42:13 PM
I'm having same hanging idle issue. checked valves, carbs still hanging/low idle and poor gas mileage.

Discovered it's my ignition coil. pulled right coil & bike could idle. pulled left coil & bike dies. Right coil was not working @ idle.
What was your mileage?  Were you getting spark from both sides?  I have the same issue with mine when I do the "redneck Carb Sync"......Pull the right plug, the idle goes down.......Pull the left plug and she stalls immediately.
Title: Re: Please help troubleshoot my poor gas mileage
Post by: BaltimoreGS on May 09, 2012, 05:00:03 PM
Quote from: craigs449 on May 09, 2012, 04:27:04 PM
Quote from: HPP8140 on May 09, 2012, 03:42:13 PM
I'm having same hanging idle issue. checked valves, carbs still hanging/low idle and poor gas mileage.

Discovered it's my ignition coil. pulled right coil & bike could idle. pulled left coil & bike dies. Right coil was not working @ idle.
What was your mileage?  Were you getting spark from both sides?  I have the same issue with mine when I do the "redneck Carb Sync"......Pull the right plug, the idle goes down.......Pull the left plug and she stalls immediately.

You could swap the coils side to side and see if the condition switches sides.

-Jessie
Title: Re: Please help troubleshoot my poor gas mileage
Post by: craigs449 on May 09, 2012, 05:22:46 PM
Quote from: BaltimoreGS on May 09, 2012, 05:00:03 PM
Quote from: craigs449 on May 09, 2012, 04:27:04 PM
Quote from: HPP8140 on May 09, 2012, 03:42:13 PM
I'm having same hanging idle issue. checked valves, carbs still hanging/low idle and poor gas mileage.

Discovered it's my ignition coil. pulled right coil & bike could idle. pulled left coil & bike dies. Right coil was not working @ idle.
What was your mileage?  Were you getting spark from both sides?  I have the same issue with mine when I do the "redneck Carb Sync"......Pull the right plug, the idle goes down.......Pull the left plug and she stalls immediately.

You could swap the coils side to side and see if the condition switches sides.

-Jessie

Good idea.........If the coil went bad, would I still get decent spark from it?  I still think that my issue is just carbs out of sync........Seems to run fine (as best I can tell) once I get her above 2,000 rpm's......just has somewhat crappy idle and the choke really does not assist in the warming of the bike.....Both sides have new plugs and strong spark...........Sound like a symptom of something? :dunno_black:
Title: Re: Please help troubleshoot my poor gas mileage
Post by: HPP8140 on May 09, 2012, 06:51:10 PM
Quote from: craigs449 on May 09, 2012, 04:27:04 PM
Quote from: HPP8140 on May 09, 2012, 03:42:13 PM
I'm having same hanging idle issue. checked valves, carbs still hanging/low idle and poor gas mileage.

Discovered it's my ignition coil. pulled right coil & bike could idle. pulled left coil & bike dies. Right coil was not working @ idle.
What was your mileage?  Were you getting spark from both sides?  I have the same issue with mine when I do the "redneck Carb Sync"......Pull the right plug, the idle goes down.......Pull the left plug and she stalls immediately.

mileage 41k. noticed bike would also misfire randomly & bog down at low rpm or when I went off throttle the engine braking wasn't as strong. when I went to remove the coil I noticed something strange. I couldn't fit a socket on the nut. the part that holds the nut had shrunk and was close to the body of the coil. that's when I confirmed...yeah something wrong here.
Title: Re: Please help troubleshoot my poor gas mileage
Post by: Big Rich on May 09, 2012, 07:05:56 PM
Ignition coils "usually" go bad at the same time. If it's running on one cylinder at idle, usually your pilot jet is clogged in one carb and not the other.
Title: Re: Please help troubleshoot my poor gas mileage
Post by: craigs449 on May 09, 2012, 08:08:14 PM
Quote from: HPP8140 on May 09, 2012, 06:51:10 PM
Quote from: craigs449 on May 09, 2012, 04:27:04 PM
Quote from: HPP8140 on May 09, 2012, 03:42:13 PM
I'm having same hanging idle issue. checked valves, carbs still hanging/low idle and poor gas mileage.

Discovered it's my ignition coil. pulled right coil & bike could idle. pulled left coil & bike dies. Right coil was not working @ idle.
What was your mileage?  Were you getting spark from both sides?  I have the same issue with mine when I do the "redneck Carb Sync"......Pull the right plug, the idle goes down.......Pull the left plug and she stalls immediately.

mileage 41k. noticed bike would also misfire randomly & bog down at low rpm or when I went off throttle the engine braking wasn't as strong. when I went to remove the coil I noticed something strange. I couldn't fit a socket on the nut. the part that holds the nut had shrunk and was close to the body of the coil. that's when I confirmed...yeah something wrong here.

No, I meant what MPG were you getting?....You said it was real bad mileage that led you to believe something was amiss.....did you check for spark at each coil before pulling them?
Title: Re: Please help troubleshoot my poor gas mileage
Post by: craigs449 on May 09, 2012, 08:10:07 PM
Quote from: Big Rich on May 09, 2012, 07:05:56 PM
Ignition coils "usually" go bad at the same time. If it's running on one cylinder at idle, usually your pilot jet is clogged in one carb and not the other.


good advice, but I have even swapped carbs and the idling problem persists on mine.  It runs better with after the carb swap, but still not as good as what it should.  Gotta hook up with Baltimoregs and sync my carbs.......
Title: Re: Please help troubleshoot my poor gas mileage
Post by: twinrat on May 10, 2012, 12:27:25 AM
check your float levels ,if one is to high it will act like you are running on choke when hot (high idle) .If your impact was real high you could have upset the tang which you bend to set float hight ,they are quite delicate..Question did you do any damage to the ignition rotor or ignition pick ups .
Title: Re: Please help troubleshoot my poor gas mileage
Post by: HPP8140 on May 10, 2012, 07:35:22 AM
Quote from: craigs449 on May 09, 2012, 08:08:14 PM
Quote from: HPP8140 on May 09, 2012, 06:51:10 PM
Quote from: craigs449 on May 09, 2012, 04:27:04 PM
Quote from: HPP8140 on May 09, 2012, 03:42:13 PM
I'm having same hanging idle issue. checked valves, carbs still hanging/low idle and poor gas mileage.

Discovered it's my ignition coil. pulled right coil & bike could idle. pulled left coil & bike dies. Right coil was not working @ idle.
What was your mileage?  Were you getting spark from both sides?  I have the same issue with mine when I do the "redneck Carb Sync"......Pull the right plug, the idle goes down.......Pull the left plug and she stalls immediately.

mileage 41k. noticed bike would also misfire randomly & bog down at low rpm or when I went off throttle the engine braking wasn't as strong. when I went to remove the coil I noticed something strange. I couldn't fit a socket on the nut. the part that holds the nut had shrunk and was close to the body of the coil. that's when I confirmed...yeah something wrong here.

No, I meant what MPG were you getting?....You said it was real bad mileage that led you to believe something was amiss.....did you check for spark at each coil before pulling them?

I usually switch to reserve between 150-160. Was only getting 130. Yeah the right coil was intermittent at idle/weak spark.
Title: Re: Please help troubleshoot my poor gas mileage
Post by: craigs449 on May 10, 2012, 08:17:05 AM
Quote from: HPP8140 on May 10, 2012, 07:35:22 AM
Quote from: craigs449 on May 09, 2012, 08:08:14 PM
Quote from: HPP8140 on May 09, 2012, 06:51:10 PM
Quote from: craigs449 on May 09, 2012, 04:27:04 PM
Quote from: HPP8140 on May 09, 2012, 03:42:13 PM
I'm having same hanging idle issue. checked valves, carbs still hanging/low idle and poor gas mileage.

Discovered it's my ignition coil. pulled right coil & bike could idle. pulled left coil & bike dies. Right coil was not working @ idle.
What was your mileage?  Were you getting spark from both sides?  I have the same issue with mine when I do the "redneck Carb Sync"......Pull the right plug, the idle goes down.......Pull the left plug and she stalls immediately.

mileage 41k. noticed bike would also misfire randomly & bog down at low rpm or when I went off throttle the engine braking wasn't as strong. when I went to remove the coil I noticed something strange. I couldn't fit a socket on the nut. the part that holds the nut had shrunk and was close to the body of the coil. that's when I confirmed...yeah something wrong here.

No, I meant what MPG were you getting?....You said it was real bad mileage that led you to believe something was amiss.....did you check for spark at each coil before pulling them?

I usually switch to reserve between 150-160. Was only getting 130. Yeah the right coil was intermittent at idle/weak spark.

Got it, I have to make the reserve switch at 160-170, so I am right on par,,,,just a little throttle heavy  :icon_mrgreen:  On another note, I have strong spark on both plugs, so the carb sync is next on the list......
Title: Re: Please help troubleshoot my poor gas mileage
Post by: HPP8140 on May 10, 2012, 06:30:29 PM
pic of offending coil. notice how close top screw hole is to body compared to bottom end. shifted somehow.

(http://s14.postimage.org/4km88nt01/get_attachment_aspx.jpg) (http://postimage.org/)
image upload (http://postimage.org/)
Title: Re: Please help troubleshoot my poor gas mileage
Post by: iv76erson03 on May 17, 2012, 10:25:28 AM
In the process of tearing apart the bike.

Choke lines seemed to be working fine. Carbs look clean as can be from what I can tell. I was trying to check the float heights but on the one carb, there is something electrical connected to it blocking the last screw. I can't get that something off without stripping the screw. Any ideas on getting these screws out? I tried the hitting it with a hammer method and that didn't work.

I'm going to put a new air filter in there because it look a bit dirty, don't know if that was the problem or not.

Wish I would have seen Kerry's guide on checking the float height before i tore the motorcycle apart  >:(

edit: I got the one float bowl off and checked the height on it. I appeared to be between 11-12 mm, which i know is low. Could low be the problem of smelling like gas, high idle, and poor gas mileage?
Title: Re: Please help troubleshoot my poor gas mileage
Post by: Paulcet on May 17, 2012, 12:54:14 PM
Yes. However,  I found the upside-down-try-and-fail-to-measure technique to yield unsatisfactory results.

Instead, I used the u-tube method, removing the bowls while the carbs are still on the bike. You can do this, too, if you replace the JIS (looks like Philips) screws with socket-head cap screws.