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Discussion Starter #1
I’m working on a 71 Z50a basket case ! I just rebuilt the engine . It has a K3 carb , high flow air filter , performance cam from DrATV, stock exhaust . What I really need is a good carb recommendation . Will a 20mm AFT carb from TB work well with this combo . They appear to have plenty of jets available for tuning . I can’t seem to locate main jets for the K3 that came with this bike
 

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Personally, I don't believe that a TB Parts 20mm carb would work all that well on a stock 50cc engine with a 13mm(maybe) intake opening on the head
 

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Discussion Starter #3
I measured the intake port on head at 17mm. I’m running a performance cam ( mid to upper power) . With the k3 carb it ran good at idle but hesitated / stumbled to come up past 1/4 but would come up , running it on bike stand in gear . I put it in the ground and it falls flat unless I choked it . Then i could ride it somewhat as long as I choked it . Idled great no choke . My next step was to riches up the main jet by drilling it to .022 stock was roughly .018 . Ran again with no choke and ran pretty descent up to wide open throttle- then bogged unless I choked it . So I then went to my next size up .032 ( too big I know ) , but when I rode it it was tough to get up to speed but once it revved out some it took off really well at wide open and popped a little wheelie going into 2nd . I turned around and tried to get back up to speed with no luck -running rich . Pulled spark plug and it was black. Cleaned plug and ran again with same result . Tried lowering needle setting several times but the needle on this carb has a severe jump from .062 to .085 with about 1/8 inch . I’m sure I need a needle with better taper characteristics. But can’t find any supply of main jets or needles to fit the K3 carb . So I really hope I get somebody here has had similar issues and can give me a good carb recommendation . Thanks in advance for any advice
 
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