Idle issues. HELP!
 

Hey everyone.

I just bought a 99 gz. I'm loving it so far, or rather, would be if it was idling properly. I'm hoping somebody has run into this problem before and knows what's up.

The bike starts fine, but requires constant revving to stay running. If I close the throttle the idle will slow down slowly till the bike dies. I've adjusted the idle speed, but when I get it to a place where the bike idles "properly" it will stay at a very high idle after revving and sloooooowly work itself down until again, it dies.

EDIT. Also, the bike will only run with full choke. I was stupid and assumed that when the lever was pulled all the way towards me choke was off. It's actually opposite, choke pulled forwards is choke on, choke pushed all the way back is no choke. This leads me to believe, as Raul said, there may be a vacuum leak as when I turn the choke off, the bike dies. My first step will be to make sure everything is sealed, then to play around with the fuel/air mixture screw, and lastly pull the carb and give it all a good cleaning and reset.

Anybody have any other advice for me? Think it could be something other than carburetion?

check for vacuum leaks

Alright, and how would I go about checking?

I'm not sure, use the 'search' here for 'vacuum leaks' I'd say. I think you need a can of starter something (ether) and then spray it near the hose between the air box and the carb, then if the revs/sound changes considerably, it means the vacuum hose gets some false air. Take apart, clean, put back together.

Other info, when the engine is hot the idle is faster than when it's cold, so don't adjust the idle until the negine has completely warmed up.

The way you describe it, it could also be a clog in the carburator but (knock on wood) I don't have any experience with that either.

Like they said while engine is running spray some carb cleaner around not in the air intake tubes going from air box to the carb where they connect to each other and listen for a change in the sound of the motor. if it changes you do have an air leak. If no leak then clean the carb. and as 5th bike stated only adjust idle knob when the engine is warmed up. You do have fresh fuel right?

WD-40 will work also. ;) :)

When I got my gz it had the same issue t was a 01 and I had to tear down carb. Didn't even need choke after so I yanked it off. It's not too difficult to clean em and it's a good idea when you get a bike to get new oil gas and clean carb,save many bloody knuckles and headaches later.

Thanks for the info everyone. I pulled and disassembled the carb tonight after work. I checked the jets, they looked clean but I ran some copper wire through them just to be sure. Didn't have any carb cleaner on hand though so I will have to blast everything with it tomorrow night. What's the best spray for me to buy to get in all the nooks and crannies?

Any pressurized carb cleaner will work. Buy the stuff at Walmart because it's so cheap and get 2-3 cans just to have on hand. If you have a lawnmower, you need some around anyway ;)

You have to be a little careful with poking anything into the orifices, even brass, because it can stratch if you're too man-handed.

Based on the symptoms you've described, I would say you definitely had a leak somewhere in the system. Giving a good cleaning is going to be beneficial in the long run, but I don't know what you will stumble across what was making the slow idle-down problem to start with.

There are only 2-3 vacuum hoses that you would need to check. And the rubber connectors at the carb inlet and outlet are known to deteriorate over time, which would be a place that air can sneak in.

Let us know once you get it all buttoned back up and running again. Once you do, blip the throttle. The behavior of the idle after you blip the throttle will tell us a lot.

Well, I got everything all cleaned out tonight and got the carburetor back on the bike.

When I put it back on I made sure the rubber boot on either side was properly seated and the clamps were cinched down as tight as I could get them. I started the bike choked and it started up perfectly and sounded pretty normal. As I slowly cut the choke though the bike started revving higher and higher so I panicked and closed it again. I let it idle for a few more minutes with the choke on before I tried again and this time it was good! Revs up nice and comes right back down to an idle!

It seems like this bike just needs an extra few minutes to warm up before cutting the choke completely. Other than that, it's running like a completely different bike than when I got it. Thanks for everyone's help and advice. I think you were right about the seals letting air in.