Hello everyone , my name is Taylor and I just got my first bike last weekend. It's a 2007 gs500. When I picked it up, my friend rode it home for me since he had a license. Well tried at least. It was doing fine in town but when we got to the interstate, it kept bogging down and dying every few miles. I did some research and decided it was the petcock issue. So I finally got the bike home and started working on it. The dealership said they changed the oil, cleaned the carbs, etc. Turns out they didn't do much at all. So I did all the basic maintenance stuff and I replaced the petcock with an on/off valve. It wouldn't start at first, but I found my mistake and fixed it. This was last night. After that I took her for a spin and it ran fine under about 5k rpm. When I would give it gas to accelerate, it wouldn't rev past 6k. When I was stopped in neutral it would rev fine.  I'm gonna replace the spark plugs and run some seafoam through the tank. It sounds like the carbs need cleaning probably. Anybody have any ideas? Thanks

Was there debris in the tank when you drained it to change out the petcock?
Did you swap out the tank petcock or the frame petcock?
Does it have an inline fuel filter and if so is it clogged?

I changed out the frame petcock. I didn't completely drain the tank, but we did drain some of it when it kept stalling on us and put fresh gas in. I don't have a fuel filter yet but I will be putting one on tonight. I didn't see any debris when we drained the tank though

I would go ahead and drain it all he way into a clean bucket to see what is in there. Might also want to pull apart the tank petcock and clean it out. If you still have the issue OR if there was debris in the tank you should go ahead and take the carbs off and clean them.

Instead of rpms, how far do you turn the throttle?  It almost sounds like a clogged jet (maybe main? depending on throttle position)

I honestly doubt its the petcock (cue adidasguy's petcock rant  ) ... do you try running it on prime before taking it out?  Prime and 'ON' can act like a regular on/off petcock.  Prime when running or off with be regular flow, without vacuum and will allow unrestricted fuel flow that is only stopped by the needle valve/floats working together.  ON position will stop the flow when the bike is turned off.

- Bboy

That's with full throttle it won't rev past 6k. I know for a fact the petcock was bad though because I took it apart and the seals were bad and the o ring was broken. And we did try it in every position with the same results

Ok, just checking since the petcock is a common scapegoat 

- Bboy

Ok so some things I'm going to try when I get the time:
1. Completely drain and clean gas tank
2. Clean and inspect carbs

Anything else I should do or check?

Also would it be a bad idea to run on reserve all the time? Right now I have it hooked up to on. But I would like to use reserve just to be able to use a little more gas. I'm not sure where it picks up fuel from on reserve. Is it low enough to pick up all the debris and gunk that might be in the bottom of the tank?

I would run it from the 'ON' location of the tank... then IF you forget and run out of gas, you can still switch the hose to reserve (and you don't have that concern about debris from the lower portion anyway).  It would be a pain to switch hoses on the side of the road, but its better than actually running out of gas.  Being a new bike to you, you don't know exactly what mileage to expect and for which to calculate.

The reserve is just under a gallon on the 01+ tanks (possibly a little different for California models?) The overall capacity of the tank is about 4.5 gallons total

- Bboy

Thanks I didn't think of that but that's a great idea incase I run out

Start the engine and hold the revs at 2000-3000 RPM and pull each of the spark plug leads and see if it makes any difference. If one of the cylinders is not firing it could lead to low RPM in gear.

Could be I'm gonna change the plugs out anyway so ill check it while I'm doing that. I don't think that's it though because it runs fine and sounds fine around 3k. It feels like it's just losing power when I open the throttle

Fuel Flow - Carbs Dirty, fuel screen in tank, kink in hose.
Air Flow - Air cleaner OK?  Is something blocking it?
Ignition - Try the spark plug test mentioned earlier.  Is there strong spark on BOTH cylinders?

I'm tending to think it's fuel flow more than anything.

Check float heights, read the plugs, make sure the choke is turning fully off, and check your air filter!

Air filter is clean. Could be a pinched fuel line. I'm gonna rerout my lined and see. As for spark, at idle if I pull the right plug wire the bike dies. If I pull the left one it stays running. How do you clean the screen in the tank? It looks like fine but it wouldn't hurt

Quote from: tcoffin014 on February 28, 2013, 05:24:45 PM
Air filter is clean. Could be a pinched fuel line. I'm gonna rerout my lined and see. As for spark, at idle if I pull the right plug wire the bike dies. If I pull the left one it stays running. How do you clean the screen in the tank? It looks like fine but it wouldn't hurt

Well there yer problem right there..
Something going on with the right cyl. What do the plugs look like? Be sure to keep track of right and left plugs..

Petcock, petcock?

Oh boy, do I have a petcock tip of the day for you!

Replace it with a pingel unit and avoid vacuum headaches.

CAL: I think you have it reversed. LEFT is the problem, not right.

If you pull the left wire and bike runs, that means the left cylinder wasn't doing much and the right is running the bike.
Pull the right and bike dies means the right was doing all the work. With it unplugged and bike dies its because the left cylinder isn't doing anything.

If you pull one or the other and the bike still runs but a little different then you can assume both sides are OK and do the Hillbilly Carb Sync where you get it so the bike slows down the same whichever plug you pull. That's also a quick way to see if you do need to do a carb sync.

XUNE: Please don't go there with pingles. Vacuum petcocks are just fine. If it goes bad, replace it. Oh, wait, that was one of Justin's funny fix-it's? Sorry, I missed the joke.

I've decided it's the carbs. When I roll in the throttle easily, it does fine but as soon as I open it up it bogs down. So I'm going to clean the carbs. I might as well rejet them while I do that. Any recommendations on jet size?