Suzuki carb question

[Stunmai]

LTZ250, 03 but like new condition. Bone stock everything. Several tanks of new gas run through it. This bike is extremely cold natured as far as getting it to idle when cold or warm. After it's warmed up it rides nice, but seems that after a couple hours of riding the idling problem comes back, refuses to idle. If I turn the idle screw up or adjust the cable at the throttle lever (same thing, right?) the idle soars, there is no just giving it a few more idle rpms. Here's something else- when revving it while in neutral, the revs take a long time to come back down to idle.. No, nothing in the cable is sticking, it's something in the tune.

Now I'm sure the answer will be clean the carb, which I am going to do, but I would like to know what I am looking for instead of just cleaning blindly and 'hoping' that fixes it. Thanks in advance.

[TRX450R_Racer]

Cleaning the carb is a good idea. While the carb is off you need to take the plug out that covers the air/fuel screw so you can adjust it.

There is a diagram here.
http://www.bikebandit.com/2004-suzuki-lt-z250-carburetor/o/m19085sch648708

You can use a self tapper to make a hole in it the grab it to pull it out. Now after you clean the carb you can adjust the air/fuel mixture so you can smooth out the idle. The mixture screw is #27 and the plug I spoke of is #23. The plug can be seen with the bowl on the carb. It comes up from the bottom so it's hard to get to. They make a special tool for getting at it but you can use a 1/4" drive 1/4" socket with a screwdriver bit in it. You can usually do it with the socket/bit and you fingers.
I would clean the carb by removing the bowl, which for some reason doesn't have a part # in the diagram. Hopefully you know what the bowl is. Don't try to take the bowl off with a phillips screwdriver. You will strip them out. Use a 1/4" drive ratcket, 3" exstention with the 1/4" socket and a #2 phillips bit. This will remove them without stripping the heads out.
Next remove #16, 28 & 29. Use carb cleaner on them. Then get a piece of stranded wire and push it through the jets. Shoot carb cleaner in every opening of the carb body. Then full the bowl of the carb cleaner high enough to soak all the jets for a day. After that reasembly it.
Then back off the cable and idle screw. Warm it up then play with the idle screw, probably by going out until it idles. I would start by turning the air/fuel screw #27 in until it seats. Don't tighten it. While turning it in count how many turns it is out by 1/4 turns. The back it out to where it was and go another 1/2 turn. Then go from there after it's warmed up. Don't go past 2 3/4 turns. After that it might fall out.
Good Luck

[Stunmai]

Thank you for the quick and thorough response. I will let you know how it turns out. Btw do you know of problems with the fuel tank valve, I read in another thread that they are problematic and to plug the vacuum line going to it and run it on prime.

[TRX450R_Racer]

You're welcome. I'm not familiar with the problem with the petcocks on those quads.  Doing that should be fine as long as the needle is seating properly in the carb.

[yfz122]

Those petcocks are a problem. It could be causing your trouble now. Check for fuel in the vacuum line. If the diaphram is leaking it will fill your crankcase with fuel.

[hatchdemon89]

the petcocks are a common problem on them.From what ive read everyone just swaps them for the raptor one and solves any problems due to the petcock

[johndoe83]

I would take a old toothbrush, pull the pilot jet, use degreaser or carb cleaner or acetone, scrub it good get the bristles in the tiny holes on the pilot jet, then blow it out with a compressor, clean carb again, reinstall with the fuel screw 3 turns out.

This sounds like a classic pilot jet issue.

[Stunmai]

Thank everyone for the replies and I will let you know how it works. Now if I could ask a second question in this same thread

I have a second LTZ250, runs good with mild idling problems which I will attempt to improve with a petcock and carb clean. Now this bike has a performance muffler on it.. Should I change the main jet while I'm in there to richen it some? Any suggestions?

[TRX450R_Racer]

Main jet has nothing to do with the idle. If it runs good when on the gas the main jet is fine. The pilot jet circuit is what influences the idle. You need to do to that carb what I described in my first response. You need to pull the plug covering the air/fuel screw and adjust it once the quad is warmed up to running temperature.