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Carburetor info. needed CH20

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Can someone help me figure the carb on my Sunstar? I'm trying to figure out why it hesitates when I increase the throttle off idle and does the same when I back it back down. All basic things have been checked. Gas, filters etc... It starts great and seems to run fine on high idle. I've only mowed with it maybe 3 hours total since I purchased a couple of months ago. It has 590 hours. I've commented on here that I thought it missed or was not as smooth as I thought it should be but I've never had a twin Kohler before so I'm clueless b/c of no benchmark. I did check the rpm and it idles low at 1500 and high at 3200. Plugs are brand new. Not sure if the modules could be weak or are they something that either goes bad or are good...? If I remove the air cleaner and fool with it what screw should I mess with to see if I can change the hesitation? I may throw some carb cleaner down it's throat. The base and body look fine on the carb, no leaks etc... I've run seafoam thru it and premium gas.

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Okay, I'll look into it. I realize that could be the delay off of idle if idling up or down but I'm still not sure why it seems not as smooth as I'd like it to be. Is there really much of an adjustment on the carbs for these CH20's? No smoke, starts great...I don't want to chase a ghost...?

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Hi Heron I have a 18hp sunstar that seemed to me was missing,idled rough pulled the cover off pump to grease the u-joints on drive shaft and found the universal wasn't but half way on the pump shaft.I'm going to add a 3/8 spacer to the engine end of shaft to cover all of the spine of the pump shaft.U-joint would wobble on pump shaft.

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