Poor Throttle...Low Power

[Heffe]

I recently had a fuel-line leak problem (fixed), which led me to a float bowl leak (replaced), and now I'm having trouble with my throttle response.

Basically, the bike idles nicely, but the choke and snapping the throttle sometimes kills the bike.  This would lead me to suspect a lean mixture, right?.

I'd like to know what would be causing my other symptoms, and if it's related to the mixture.

When I'm riding, the bike is sluggish and very slow from a stop (sometimes stalls)
When I finally get up to speed and roll the throttle full on, there is no response.  As I let go of the full throttle, the bike jumps as if the throttle were being revved.
I also checked my float heights and they appear to be alright, although one of my float needles has developed a small groove around the rubber tip. 
Should it be replaced?  That would make it run rich right?

Any suggestions are welcome.

I'll start be replacing the float needle and adding some carb cleaner to my tank.

[Ronin]

Just a guess,but check the throttle cable.See if it's binding.And on the carb end check the nuts to see if somethings loose.Had a simular problemo once,it was the cable sliding with the sleve.Not down tight....

[Heffe]

I thought of that...but ruled it out because the bike changes sound when I engage the throttle, there's just low RPM response.  (really throaty, and lower/emptier)     

On a ride earlier tonight, I was going up a hill and the bike started to slow and feel bogged down....giving more throttle and downshifting a gear did nothing.  It died 100 feet from the top of the hill, so I had to push it up and go from there.

When I'm crusing and put WOT there is no response, but sometimes little jolts while it's held open and always a jolt when I release.  The sound changes so the throttle is opening in the carbs, but the RPMs don't change.  Lean maybe?

Anyone else have any suggestions?

[pkhoff]

What size jets do you have.  Are you using the restrictor that came with the aircleaner? If you are using the K&N without the restrictor you need to rejet. You need a rejet even without the K&N if you have a U.S. bike.

[Heffe]

I'm pretty sure everything in my carbs is stock, as far as jets go.

I took them apart and cleaned them out at the beginning of the summer when I got the K&N drop-in and she ran great. (yes I have the restristor ring on)

Does anyone know a good link or method for cleaning out the gas tank....I know that mines rusty, and I'm thinkin if I don't fix the rust in the gas, it'll just keep clogging my jets.
I have an inline fuel filter installed, but it doesn't seem to be doing that good of a job.

It is a U.S bike, but I was told it'd be fine with the restrictor.  Maybe I should rejet?

[bikejunkie223]

I'd be suspicious of a fuel filter that wasn't designed into the system.

[Heffe]

Well, I just checked my plugs and the left side (one that has the slightly worn float needle) is completely soiled black.

So, guess I'm rich on that carb, which is to be expected with a worn float (not sealing right).

I'll replace that and run some more cleaner through the carbs.  Should I replace the plug now that it's all black and soiled?  Should I clean it, and with what?

Does running rich make sense with the WOT no response, and the jumpy acceleration when i let off the throttle?  That's confusing me, cuz there's zero response except for a change in sound.
Also, my RPMs are slow back to idle, so I had thought lean, but maybe it's from me adjusting the idle screw for the rich problem.  We'll see.

Love this site by the way, priceless.

[Heffe]

After reading a couple other forums, I'm pretty sure my micture is too rich (hopefully due to the faulty float needle)

I was confused about the lack of throttle response and the jumpy accleleration when i let off the throttle, but now I'm pretty sure it's all related to the rich mixture.

I'd like to be reassured by a more experienced rider, so any more input is much appreciated.  Also, what can i clean my spark plug with and does anyone know a cheap place to get float needles for the GS....Suzuki dealership said $41 a piece.

[bikejunkie223]

If the mixture is rich enough to foul the plugs badly then the bike can be misfiring, and instead of a twin you have an intermittent single- that will wreck your acceleration and throttle response pretty quick.

[Heffe]

Makes sense.  Acceleration is hardly the word I'd use right now. 

Hopefully once I replace that worn float needle she'll be back in action.  Weather's been so nice here too...frustrating.

Thanks for the input.

Again...anyone elses 2 cents is appreciated.  I'll update when I replace the needle.

[rylon]

The only thing I can find on bikebandit is the whole float assy.  Don't know if the valve/plug is sold seperate, but it looks like 20-30 dollars depending on what year bike you have.  I would ask Buddah if he has an extra lying around he would be willing to part with, unless you think that float needs to be replaced as well, your call.

While I had everything apart I would balance my carbs, I just did it this past weekend and it made a world of difference, and it was super easy.  I also had an aftermarket fuel filter installed and it played havoc on my fuel system.  Just food for thought.

Rylon

[Heffe]

Is there a good link to balancing the carbs.  I've taken them apart to clean them, but I'm not sure what all goes into balancing them.

My floats all work perfect as far as I can tell, so I would just need the needle/plug.  Gonna check a local salvage shop here in St. Louis.

I've had the inline filter in since May, and this is the first fuel related problem I've had, so I'm not sure if it has anything to do with it.

[JeffD]

I've had an inline fuel filter on my '96 for 27,000 miles with no issues; so I would stick that on the bottom of the list.

A 'cheap' way to clean a sparkplug is to run some sandpaper between the tip (both sides), or just go pick some new ones up for a few bucks a piece.

I recently rebuilt my 96-GS500 and was having a left side carb issue (still am but..), and yeah if one cylinder is not firing you'll barely get anything out of it.  A simple way to test if its a carb issue is to grab some carb cleaner, start the engine and spray carb cleaner into that carb.  If the engine suddenly rev's up you know its a carb issue; if it does nothing then its a spark/ignition issue.

[rylon]

Balancing the carbs is really easy, there are some threads on how to do it but I'll give you the quick and nasty.

1. Disconnect the fuel tank in your usual manner and connect the fuel lines to a temporary/tuning tank  ( I bought a universal coolant overflow tank at my local parts store, works perfect)

2. Assemble the balancer using this diagram http://devils.eng.fsu.edu/~rhunter/gs500/CarburetorBalancer.png  (Fill it with water, don't use oil because if you do and it gets sucked into your carbs it will require you to take them apart and clean them)

3. Disconnect the carbs from the carb boots, leaving everything else in tact.

4. Disconnect the vacum line from the right carb.  (It is a brass nipple on the left side of the left carb if you are looking at the carbs from the side that connects to the carb boots)

5. Connect one side of the balancer to that nipple.

6. Remove the rubber cap on the other vacum port on the other carb.  (It's in the same location as  the first one but is hidden by the choke assy.)

7. Connect the other side of the carb balancer to that nipple.

8.  Set the petcock to PRI and allow the float bowls to fill up

9. Completly open the valve on the balancer setting it to its least sensitive setting.

10. Start the bike and allow it to warm up.  (If all the fluid is sucked into one of the carbs roughly adjust the balance, refill the balancer and start again)

11.  Balance the carbs using the screw between the carbs close to the top side of the idle adjustment screw.

12.  Once you are happy with the balance of the carbs with the valve in the balancer completly open slowly close it, making the balance more sensitive, and adjusting the balance untill the valve is completly closed.

13.  Remove the balancer, replace the vacum line to the petcock and re-cap the other line.

14. Re-install the gas tank and enjoy your freshly balanced carbs.

I have taken pics of the whole process, but I haven't taken the time to make up a how to.  If anyone would like to add to this I would welcome your additions.  I plan on adding a detailed how to both to the forum and the wiki, but lately my time has been taken up planning my wedding!

Thanks Rylon