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Post by peteyparado on Mar 24, 2012 9:58:25 GMT -5
Got a new cvk 23mm carb installed it on my 50mm bbk with matching head with bigger valves.. An a9 cam... I start the scoot idles ok as soon as the trottle is open even a mm or 2 it dies... Tried adjusting with the air mix but still same result.. The carb has a 95 main 35 pilot...timing is spot on
help
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Post by larry001964 on Mar 24, 2012 10:05:00 GMT -5
Got a new cvk 23mm carb installed it on my 50mm bbk with matching head with bigger valves.. An a9 cam... I start the scoot idles ok as soon as the trottle is open even a mm or 2 it dies... Tried adjusting with the air mix but still same result.. The carb has a 95 main 35 pilot...timing is spot on help Are you running the stock airbox or a unifilter ? |
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Post by dude on Mar 24, 2012 10:08:15 GMT -5
Just guessing maybe lean. Try richen up w/ the needle.
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Post by peteyparado on Mar 24, 2012 15:07:32 GMT -5
larry unifilter..
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Post by Deleted on Mar 24, 2012 15:38:14 GMT -5
sounds lean to me too
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Post by larry001964 on Mar 24, 2012 15:48:09 GMT -5
Yep I'm thinking your lean as well, try as a test putting the stock airbox back on and try it.. I'm almost betting it will perform better. The stock airbox will draw less air than the unfilter and this will help richen the air/fuel ratio mixture some..
Your AF screw only really effects your idle mixture, and has almost no effect on anything after idle.. So the airbox will suck less air but your 95 jet will put out the same amount of fuel richening the mixture.. you will have slightly less total flow but that airbox is designed with the 18mm carb in mind meaning its Air to Fuel ratio and flow rate is good up to about 90 cc as I understand it.. So it should still work with your 23mm carb.. If you can get the rubber over the back side of the carb..
Your other option if you can't use the stock airbox is to partially cover up the unfilter.. Ive seen people use duct or black tape to do this. Idea is the same, to slow down the airflow to enrichen the A/F mixture.. It's harder to get it right than using the stock airbox but I've seen others do it..
My Scooter i use a 39 mm flex pipe, got rid of the rubber hose, and I drilled 4 3/8" holes on the under side of the airbox cover lid, I can tape them up or untape them to control my A/F mixture above idle. The carb needle controls fuel flow in the carb and I have the airbox to control Air flow so I have control on both..
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Post by Deleted on Mar 24, 2012 20:30:03 GMT -5
a 23mm carb is kind of big for a motor less than 125cc anyway. too big of a carb will rob performance not gain it..because velocity is less. the fuel will not atomize correctly if you go too big. bigger is not always better. an 82cc 139qmb makes about 5 hp so according to the chart the max is about 18mm.  sources for the above: 49ccscoot.proboards.com/index.cgi?board=carb&action=display&thread=136649ccscoot.proboards.com/index.cgi?board=4ttech&action=display&thread=2758I agree that it should run with that carb but i dont see how you could get any gains from it on such a small displacement....IMO it will rob performance. a 95 main on an 82cc with 18mm carb works great so with that size carb you certainly need to go larger on the main but i doubt the small displacment is going to make the best use of that much extra gas...even with a big valve head and cam. |
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Post by reveeen on Mar 25, 2012 2:34:23 GMT -5
You have something else going on there. Maybe you missed the cam by a tooth, or assuming you are using a 150cc manifold, you didn't trim the shroud, and have a vacuum leak.
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Post by Deleted on Mar 25, 2012 6:04:52 GMT -5
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Post by Deleted on Mar 25, 2012 6:13:30 GMT -5
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Post by Deleted on Mar 25, 2012 6:22:07 GMT -5
your carb doesnt have an accelerator pump either does it?
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Post by peteyparado on Mar 26, 2012 1:34:23 GMT -5
yes it does.. its the 23mm cvk carb from scrappydogscooters.com
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Post by larry001964 on Mar 26, 2012 8:28:35 GMT -5
Have you taken a compression test yet ? Did you try the airbox trick ? If you did what did it do ?
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Post by larry001964 on Mar 26, 2012 10:25:42 GMT -5
a 23mm carb is kind of big for a motor less than 125cc anyway. too big of a carb will rob performance not gain it..because velocity is less. the fuel will not atomize correctly if you go too big. bigger is not always better. an 82cc 139qmb makes about 5 hp so according to the chart the max is about 18mm. sources for the above: 49ccscoot.proboards.com/index.cgi?board=carb&action=display&thread=136649ccscoot.proboards.com/index.cgi?board=4ttech&action=display&thread=2758I agree that it should run with that carb but i dont see how you could get any gains from it on such a small displacement....IMO it will rob performance. a 95 main on an 82cc with 18mm carb works great so with that size carb you certainly need to go larger on the main but i doubt the small displacment is going to make the best use of that much extra gas...even with a big valve head and cam. Thank You for this Fast, this graph sure corresponds with my experience on these engines. I think my little stroker is developing between 6.5 to 10 hp, ( hard to tell exactly without it being dynoed ) the carb is pretty much matching this graph.. And that scoot runs goooood... |
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Post by vegaslightsss on Sept 23, 2012 22:53:08 GMT -5
I am running the same exact setup,if you never got it sorted out,change the needle position to the little "C" Clip goes on the bottom of the 4 slots,(raising the needle) it will run like a different machine,messed around with mine for 3 days before I got it dialed in...
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