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Post by gy6808 on May 3, 2013 3:18:49 GMT -5
some one gave me a blown 2011 Chinese bigbang qmb139 50cc... so I spent some cash and put new crank, 100cc bore kit, variator, clutch spring, cdi/coil, ngk iridium plug, stroker naraku cam, leo vince exhaust, 8-1 gears... so my 26mm 150cc carb came in today and I installed it with some minor mods with the cable mount so I still can use the 50cc cable. primed it and started right up... I can definitely feel the power difference with the bigger carb.... BUT ONLY ONE ISSUE... once past 1/4 throttle... it bogs and sputters spewing black smoke... i'm guessing the jet that came with the carb is too big... I compared it to my #  jet and it looks twice as big... i'm guessing it's a #  or #100 or something like that... so now that I explained what I did so u guys can get an idea... I want to know what size jet can I use with my 26mm carb on a 100cc engine??? |
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Post by rider95 on May 3, 2013 7:15:44 GMT -5
Is the bbk 47mm piston or 52mm? why did you put a 26mm carb on a 50cc ? its way too rich you really need a 20 0r 22 mm carb
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Post by millsc on May 3, 2013 7:49:24 GMT -5
i run a 24mm carb on my 52mm kits tried 26mm couldn't get it to work regardless of the jet to much air
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Post by ej132 on May 3, 2013 10:11:03 GMT -5
How do you measure the carb? Think mines a stock one, 18mm I think. Im doing a 50mm bbk, would a bigger carb help performance? Im putting in an #  jet. |
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Post by millsc on May 3, 2013 10:35:28 GMT -5
big bore kit cam and big valve head with performance exhaust work great for me with the 24mm carb and manifold
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Post by triker on May 3, 2013 10:42:34 GMT -5
Most stock carbs are 18mm, some are 19mm. You measure the inside diameter of the intake manifold side.  This one is actually a 19mm carb. I don't have enough hands to hold the calipers right to measure correctly and snap the photo. Roy |
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Post by gy6808 on May 3, 2013 18:19:35 GMT -5
Is the bbk 47mm piston or 52mm? why did you put a 26mm carb on a 50cc ? its way too rich you really need a 20 0r 22 mm carb Its a 52mm kit... |
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Post by gy6808 on May 4, 2013 1:48:45 GMT -5
So I played around with the jets... since my 20mm carb was running good with #72 jet... I started with that... #72 on the 26mm carb... it had good power until 3/4 throttle then it would lean out... then I tried #75... almost there with some leaning on top end... then I used #80 jet... hurray.. was good... it ran great with good power without bogging... holds power better now...
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Post by millsc on May 4, 2013 8:29:53 GMT -5
Not sure your set up but i run jets over 100 on my 24mm, check your plug
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Post by hank on May 4, 2013 9:41:19 GMT -5
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Post by millsc on May 4, 2013 9:43:44 GMT -5
The bigger carbs need bigger jets also
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jet and it looks twice as big... i'm guessing it's a #
or #100 or something like that... 
jet.
but i like to run slightly lean and my plug chops look good and she runs very well