carb runing lean

[gsxr750dude33]

i have a 2000 gz250 and it is runing lean and cant find the air fuel screw can anyone help me

[Easy Rider]

i have a 2000 gz250 and it is runing lean and cant find the air fuel screw can anyone help me

It's on the bottom, covered with a metal "plug".
A downloadable service manual is available on here.

What leads you to believe it is lean? Even if you get to the idle mixture screw, it doesn't have much range of adjustment. Does it have a stock air filter on it? That is an important part of the mixture setting.

[gsxr750dude33]

i know by the way it runs and yes it still has a stock filter but i made a new ram air intake for it and i just didnt feel like just turnin screws

[Easy Rider]

i know by the way it runs and yes it still has a stock filter but i made a new ram air intake for it and i just didnt feel like just turnin screws

Maybe I should bow out of this discussion because I am about to say something that might be construed as unkind:

If you can tell by the way an engine RUNS that it is a lean mixture (versus several other things that might make it run rough), then you might have a promising career as a mechanic !! :roll:

Unlike most air filters, on the GZ, the air comes into the middle of the filter and the outside of the filter and the whole air box has a slight vacume because of the filter restriction. If you have done anything to make an air leak in the air box, you need to seal that back up because it is letting in unfiltered air. That includes the plug on the bottom of the air box drain hose.

If anything you have done FORCES more air through the filter, then you need to see the threads on here about doing a jetting and needle change and idle mixture adjustment. Like it's name, the idle mixture adjustment will only have a noticeable effect at or near idle speed. Above that, other things come into play. At what engine speeds do you notice the problem ??

[gsxr750dude33]

Its not at what speed but at high rpm and i am good with engines but better with cars. This is one of the first bikes i have worked on and the first 4 stroke. I have worked on more 2 strokes so you can see why im askin for help.

[Easy Rider]

Its not at what speed but at high rpm

I SAID "engine speed" which is the same as RPM.
I quit.

[gsxr750dude33]

sorry i missed engine i just saw speed

[cnorman70]

[quote="Easy Rider"][quote="gsxr750dude33"] That includes the plug on the bottom of the air box drain hose.quote]

What is the air box drain hose. I noticed, for the first time this afternoon, a small, narrow black hose running from "something" (can't remember now what it's attached to and will try to post pics another time) just under the seat and just hangs down and the other end is not attached to anything.

Can anyone tell me that might be? LIke I said, I'll try and post pics tomorrow. They are on my phone and I need to transfer them to a computer I can save them on first.

[alantf]

That includes the plug on the bottom of the air box drain hose.quote]

What is the air box drain hose. I noticed, for the first time this afternoon, a small, narrow black hose running from "something" (can't remember now what it's attached to and will try to post pics another time) just under the seat and just hangs down and the other end is not attached to anything.

Can anyone tell me that might be? LIke I said, I'll try and post pics tomorrow. They are on my phone and I need to transfer them to a computer I can save them on first.

Yes, thats the drain hose. It doesn't attach to anything at the bottom, because that's just what it is, a DRAIN HOSE. It should have a plug in the bottom end, to seal it & keep the vacuum in the air filter, that easy mentioned. If you haven't done so before, remove the plug & drain off any gunge that may have accumulated in the pipe. (the pipe's there to collect any gunge!) Then replace the plug. If the plug is missing, that means that the partial vacuum is missing from the air filter, & that could be your problem.

The hose hangs down from "just under the seat" because that's where the air filter is! :whistle:

[cnorman70]

alantf,

Are you saying there should be something at the "bottom" of the hose? There is a clamp up by the air filter, holding it in place, i presume...but nothing at the end of the hose.

Would i need to call my suzuki dealer to get this plug? or "create" one? I guess if there's no plug on it, it may just be draining into oblivion?!?!

Thanks for the help!!

Here's the pics I took...
(I have no plug at the bottom of the hose)

[JWR]

Just screw a bolt in the tube.
Put a wire or tie wrap to hold it in.

[music man]

That is the wrong hose, if you will notice that one is attached to the bottom of the Carb, NOT THE AIR FILTER box. You need to find the one that leads up to the bottom of the air filter box, the one you found is to drain the carb bowl.

[alantf]

Now that you've put up a photo, I can see that this ISN'T the tube you were referring to earlier. The tube in the photo is definitely the carb drain hose, & it's attached to the carb. The tube you were referring to earlier, as coming from under the saddle is DEFINITELY the air filter drain hose (which should have a bung in the bottom) Have another look under the bike, find BOTH drain hoses, & tell us which one you REALLY mean. :cry: :whistle:

[Sarris]

His airbox drain hose may be missing. My airbox drain hose is a thin wall hose slightly larger in diameter than the carb drain and has a plastic plug in the end with a metal clip.

If his is missing, he probably is running lean.

:)

[alantf]

His airbox drain hose may be missing. My airbox drain hose is a thin wall hose slightly larger in diameter than the carb drain and has a plastic plug in the end with a metal clip.

If his is missing, he probably is running lean.

:)

:plus1: :plus1: :plus1: :plus1:

[cnorman70]

I'll take a look for the airbox hose.

Is there supposed to be a plug on the carb drain hose? There definitely isn't one.

[bonehead]

No, no plug on the carb hose, just the air box drain.

[jonathan180iq]

GSXR750DUDE33,
If you're lean at high RPMs, then you need a slightly larger main jet. Tons of info on the site on how to do that.

This should only be done after you have ruled out air leaks, as suggested for Cnorman70 by everyone else.

PS: Take that ram air crap off. It's useless. This isn't a fuel injected car engine. Any gains that there might have been will be lost through the filter and air box.