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Discussion Starter #1
So I bought this bike is a 1986 sp250 susuki carb was junk and needed a new one being so old I could not find one I bough a aftermarket carb that fit at first is was getting to much gas to start so I lowered the needle and grabbed a high flow filter now it runs fine at higher rpms but as soon as it drops down to idle it will die the idle screw didn’t do much or the air fuel screw I also tried a hotter and colder spark plug my only guess now is the stock exhaust is not letting enough flow past it I’m out of ideas other than that thanks

carburetor nibbi 34mm
Air filter uni high flow two stage pod
 

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Simple check re the exhaust is to remove it....if it runs then that was the problem...I dont think it will be though. More likely is some crud got sucked through and has blocked the idle circuits. Check the filter for debris...also the tank fuel filter if still fitted and the tank itself for internal corrosion.

As to getting the carb clean you may be able to dislodge any debris by applying compressed air...this will mean pulling the carb off though and minor dismantelling. I would be tempted to run some carb through to see if that works.
 

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Discussion Starter #3
Ok I will try some of this but when I was working on it it had very low compression it had some but I could move it with my hand easily and it is a 250
 

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Given the "very low compression", you probably need to investigate that first.......because anything else you do likely will just be a waste of time.

Note: With the plug OUT, you should be able to turn it fairly easily.
And with the plug IN, there are small parts of the rotation that it might turn easily too.
IF.....you can turn it several rotations by hand with the plug IN.....then there is a MAJOR problem.
 
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