As Per Request, I have been asked to share some information that I had jotted down on another thread in regards to 250 carburetors, Particularly the 2007 GT250R as this is the bike I own. After rebuilding the carbs and getting poor results with the service manual specs I dug up various posts/ manual versions/ different bikes with the same carbs and have collected it for your knowledge. Some of these differences include:
-Incorrect float height. No attempts by Hyosung to correct. Called 5 dealers all across America, none had a clue what the correct setting was supposed to be. Mine were set
at 13mm, which was lean.
-No wet setting specification, despite mentioning a fuel level.
-Incorrect arrangement of the vacuum slide/ jet needle parts in all service manuals for the 250 motor. Assembling by the book leads to overly rich midrange due to a +2mm
needle shimming.
-No mention or revision of the carb diagram for the 2006 onward Mikuni BDS-26's, which have an accelerator pump.
-Consequently, No part numbers for those specific parts, and no method to ordering them, which leads to having to buy a whole used set for a single part. If you can find
one that is.
-No mention of the o-ring between the main jet and the emulsion tube, despite there clearly being one in my carbs
FYI vacuum pulse pumps can go suck a lemon. Who would put a pulse pump on a high revving sport bike, whose power range is CLEARLY out of optimal vacuum for the pump. A sport bike of this size sees full throttle and high rpms pretty much all the time. This is where vacuum is low/ and fuel demand is high. Not a good combo for something needing a strong vacuum. A 94 zx600 carbureted fuel pump and mounting bracket can be modified to fit (with some wiring modifications too) without any consequences to jetting. You will notice a smoother ride when ringing the bike out thanks to actual fuel supply happening where it needs to.
The FZR-2KR and xv250, as well as the XJ600 Seca II share the same carbs as this motorcycle, and the xv250 even has an accelerator pump if your looking for replacement parts on the rear cylinder carburetor. The actual pump and associated levers can be ordered ONLY for the rear carb with the xv250, as these bikes did not have ganged carburetors as our bikes do. There are subtle differences in the carb body and bowl, however, so order with caution. The xv250 manual also has a correct arrangement of jet needle parts, and the FZR-2KR's float specs seem applicable to our bikes as a good base line to work with, they both operate in the same rev range with the exact same displacement and relatively similar jetting. The spec is 4-6mm using the clear tube method on the drains for wet bowl fuel level, 6-8mm dry float height in order to ballpark the wet fuel level, with the wet fuel level being the absolute of the specification.
I also dug up an absolutely amazing rebuild on our carburetor model, and while the specs like jet size as well as the amount of carbs in this gang isn't correct, the information about cleaning and assembly is absolute gold considering the lack of information that plagues Hyosungs. A good 95 percent of this stuff applies to us, and is excellent for both beginners and experts alike.
That information can be found here:
http://www.xjrider.com/viewtopic.php?t=668If the author of this thread (or a mod) feels that this can be of assistance, feel free to pin or move it to the front of the original post, except for this line of text.
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Topic: Like Carburetor 101 for the total Idiot? (Read 77026 times)