I have a 48cc sky hawk with an nt carb,My question is why is so hard to run when cold or start.I have a 68 jet in it from sbp I think stock is 70.The plug chop seem to show that it should be good there.I have moved the needle up and down too.I have to give it some throttle to start it.I also have to play around with the choke too,revving here and there,Finally is gets going.So any suggestions.
carb question
- Thread starter wan37
- Start date
I have a 66cc unit with what they called a speed carb on it. Since I put it on, it takes a lot to get it started and have to run partial choke for a long time. This is in cooler weather [about 35 F]. I built another 66cc with a stock carb unit for a friend, and it starts right up in no time.
I had a cns carb that came with kit and it started with no throttle or choke very easy and ran great.I took if off because plastic spacer got ate up from gas and it broke.I made a copper one but never put it back on because I also messed with the float and fuel/mixture screw and got it all out of whack.So I know this engine can start and run better cold.Any suggestions would help.Thanks
How long does it take before it starts running good? These little guys like things warm. A cold start will always produce less than perfect performance for at least the first minute or so of running. They aren't like your car with computer controlled fuel delivery and ignition changes. They're simple little 2 stroke, piston ported engines that need a few moments to warm up and run right.
Having to use some throttle isn't uncommon either. Neither is using a little choke for a rich mix especially when the outdoor temperature is low.
How does the engine start/run when its warm?
Tom
Having to use some throttle isn't uncommon either. Neither is using a little choke for a rich mix especially when the outdoor temperature is low.
How does the engine start/run when its warm?
Tom
I'm not for sure how it will start and run when it's warmer outside.I know it takes about 3minutes of playing around with the throttle and choke then it runs really good.I guess it is suppose to be warmer the next couple days I will see then.
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Being a happy CNS carb rider who has watched the constant comments here telling people to toss their CNS carb in the garbage I just gotta note that you actually said your motor ran and started better with your CNS carb than the NT... Just for the record... on to your current problem.
Typically for a cold start you need to choke off the air (or add fuel from the enrichment jet from the CNS carb) to richen the mix. So my first guess is that your NT carb might be tuned a little lean overall making it harder to richen it up for a cold start. Or perhaps you have a leak that is letting your carb dry out a bit when its parked and it takes a while to get the system all primed up again? Or perhaps your spark plug has gotten fouled a bit and she's not firing like she used to? Just a couple thoughts on what might be the problem.
I must say, warm or cold, when I put my bike on the stand it only takes one kick and a quick pump on the enrichment jet and my motor starts right up every time and idles perfectly with the CNS carb...
)OK I'm the weird one that is going to put the cns back on and try it.I willing to have the patience for it.I need to know where to set the fuel/mixture screw at ?I think about 1and half screws out for a start point I basically know how to do the rest.I have read a lot of your post nightcruiser.I'm just lacking info on the fuel/mixture screw were to set it at a base point and adjusting after I get it running and warmed up.Thanks guys.
Honestly the air/mix screw is over rated IMHO, I found the adjustment to be a fine touch rather than critical. You should adjust it after the motor is warmed up and idling, then set it to the place where the idle is the best. I don't recall the recommended starting point, but I would assume 1 turn would be a fair estimate. Try it a little high and a little low, find the middle where the idle is the best/fastest. It's been a set and forget for me...
What kind of air filter do you have on your CNS btw?
I always have to take it easy for a few minutes, sometimes idleing for a few minutes first.
They like being warmed up.
They like to complain when they are cold.
They like being warmed up.
They like to complain when they are cold.
OK, same carb I am running.
I found the red air filter to be a PITA really. The foam insert would load up with oil from blowback and the motor would start running funky, so I had to keep it clean, so keep that in mind. Last season I changed over to a high flow style air filter and its worked out great, haven't had any problems for lots of miles (I grew very tired of removing the red cover to clean that foam!). I got the low profile filter, but there are several to choose from if you have more room. http://www.sickbikeparts.com/catalo...ter&osCsid=9gh4lklp5bip9mnb9m37akdtg1&x=3&y=7
I also recommend you run and inline fuel filter, cause there is a very small idle jet in the CNS carb that will clog easily. BTW, make sure to clean out all 3 jets, the main jet, the enrichment jet, and the idle jet too, if the idle jet gets clogged you will get rough low end and idle and hard starting. With an inline filter and good fuel line you should run many a mile without any issues if the carb starts out clean with a quality filter....
