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2005 Suzuki z250 quadrunner carb problems

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I just purchased a used z250 as a Christmass present for my son and it seems that it has some carb problems. Any help to get this figured out would be much appreciated. The vacum line was plugged and it would only run on prime when i got it. Seems the petcock needed to be replaced and this was the way to make it run without replacing it. This was done by a shop for the previous owner and I only learned of it after purchasing the quad and questioning the seller. A new petcock was installed and that's where I come in. The previous owner never had the job finished. So I pulled the carb cleaned everything, set the adjustment screw in the bowl to 3 turns out, reinstalled it and checked for vacum leaks. The bike will start right up and run pretty good but the problem is with the idle. When I use the idle adjustment screw to get the idle where it sounds good and then rev the bike up it hangs at a high idle before settling back down. The only way to get it to settle faster is to lower the idle adjust ment screw, but then the idle is too low. I have tried 3 turns out on the screw in the carb ( not the idle), 4 turns out, and now 5 turns out. At 5 turnsout and fiddling with the idle screw, I can get a decent idle and she will hang very slightly then come down. The hanging occurs when you rev it up and keep it up for a few seconds Not if you are snapping the throttle. Can someone help me out with this? Is the idle hanging normal? I have a 80 honda dirt bike for my son and ride a bike myself and this is not something I can say I have heard before. Thanks for any help in advance.


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Check you valves Those quads have to be checked often !!5 turns out is way to much !Did you check what jet is in there ?

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I didn't check the jet size. What should it be or rather what is the stock size? I'll take it off again today and check. I guess I should back it down to three turns if 5 is way too much. I'll look for a shop manual today also.

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I didn't check the jet size. What should it be or rather what is the stock size? I'll take it off again today and check. I guess I should back it down to three turns if 5 is way too much. I'll look for a shop manual today also.

Yea 5 turns is way too much !! I`m not sure what jet size is in there You may need to change you jetting a little !! Let me know what size is in there !

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There was a 138 main jet and 20 pilot jet. After a little more searching it looks like it was jetted to run with a modified box and the slip on. I found this out after installing a stock rebuild kit. So now I am at a 125-126 ( that's what was printed on the main) and the 20 pilot. The bike has a yoshimura slip on and I guess I'm going to be too lean the way it is now. I orderd a Dynojet kit which is what I should have done first. I am not looking for this bike to have every last drop of power just yet. It is my sons first quad of his own and it is much bigger than what he is used too. I'm still a litle confused about the "hanging idle" as the bike was running very rich and so far what I have read says that too lean was the culprit.

Can you tell me what the third jet is for? I can't make out a number on it but in the schematic it as listed as a main jet( part number 17) with a note. The only thing is the schematic doesn't have the note. Also should I run it with the stock jet first and see what I have or is that a waste of time? I don't want it to be too lean. Thanks for the help so far.


Edited by archer292

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