largest carb for a chinese 80cc bike kit

dondupuis

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Hello. all
I was wondering what's the largest size carb anyone knows of being installed on these bike kits. I just finnished installing a 42mm Keihin carb on mine and seems to run as well as it did with the stock carb. now it's time to try tune it for top speed. I trilled out the main jet in my stock carb to 1.5mm lol guess what pretty much had to hold a truck box till i was up to speed to match the fuel.. but anyway i figured if i want more fuel ill just install a larger carb. anyway point is will this tune to run right or wasting time.?

Thanks

Carb is now install with the help some of hoses and clamps
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After some more googleing i found this carb is used for 50 - 110cc 2/4 stroke engines. looks like i have some tuning to do.. :)
 
it's not just the engine size that counts but also the max RPM.
20mm is the biggest useful size for your size engine maxing out at 7000 rpm.
anything more than that offers no advantages.
but the Keihin is a fully adjustable carb, unlike the crummy stock carb.
have fun!
 
cool. i had this one already. thought i would give it a go. so much better than the old one. at 1/4 throttle 2700rpm i now cruise at my old top speed @ 5600rpm. i thought i was having jetting issues as it only seemed to be lacking at the top end. i have expansion chamber from a pocket bike modded to fit. but have not done any porting yet. should I? I am currently running rich it seems as its very boggy. what im wondering is while im cruising alone and it's bogging every once in a while it will start to sound like a 2 stroke should and accelerate some but then back to the bogging. it's weird cause to me it acts like it wants more fuel.

any thought and suggestions would be great..
 
I like using 19mm carbs on mild engines, highly modified gets 26mm. any bigger doesn't do you any good
 
i only went with the one i have cause there website said 50 - 110cc use so though has to be better than what it came with.

also looking around online for some info about modding the CDI and coil from the 110 to work.. not so sure how to connect it up..

my compression is at 120psi should i bump it up?
 
I don't recommend any more than 135.
the chrome plating on these cylinders is weak. more compression means more outward force of the rings on the cylinder, leading to flaking off of the chrome.
 
if i take a mm of the head would that be to much. is there a rough average as to how much compression 1mm would add. ? I seen another post with the fella that has a very large expansion chamber installed. love that.. looking at some of my sleds to see what one is going to donat a pipe.. lol im just working on uploading a video. i will post soon. maby you can recommend some things..
 
if i take a mm of the head would that be to much. is there a rough average as to how much compression 1mm would add. ? I seen another post with the fella that has a very large expansion chamber installed. love that.. looking at some of my sleds to see what one is going to donat a pipe.. lol im just working on uploading a video. i will post soon. maby you can recommend some things..

Do you think this CDI and coil will work with these engines?
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Here i have added photos of spark plug,head and piston. things don't look to bad. this kits is just coming on my second year with it. it's my sole means of transportation.

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