hello. i got a phbg caruburetor 21mm. i use a 72cc bike 2-stroke. this isn't a mini its a little bit bigger. im just trying to figure out how to tune this carb. i need somebody who knows how to tune a dellorto. whats going on when you turn the screw. i cant figure out some basic stuff.
like what does the motor do when you cut off the fuel mixture screw? an air screw carb, well, depending on how much fuel, it would just quit. im just wanting to know, what a tuned scooter would do when you cut it off. on this carb. i would think it cuts the mixture off, bike dies, all it has is fuel from the next jet.
so i got this bike. well. so watch this video of it. i turned the screw in almost every direction trying to tu.. ok. there are 2 videos. at teh beginning of each i try to tune some. turning the pilot screw. and turning the idle stop screw. the first video, which is actually the second, i made it after, is just tuning the carb. this is whats going on. i do a little trick
ok. stock jetting. i start it up. or its running there. the mix screw, oh 1 1/2 turns out. turn the idle screw, got a good idle. ok, so then i turn the mixture screw. i turn it out, nothing much happens. i turn it in, revs a little higher, gets to where its almost off, revs pretty high. close off the fuel screw? it makes a little whistling noise and revs the highest... ok. so maybe its somethign to do with pressure. i lower, the idle stop screw, turn it out, you know. it gets pretty low rpm. then i turn out the mix screw, wondering if it will kill it, it for a second seems to drop, then it starts revving higher. after 1 1/4 turns it starts to stall.
ok. but if you read the manual. it says well, they shut off the slide on racing bikes. and tune it with teh idle at 1400 rpms. then you tune it to around 1200 rpm, you knmow for idle. after setttign their tune, racing bikes, close the idle stop screw by turningn it out until the slide is closed.
well. seems like the slide was close to closed and mabe instead of tuning my bike i was doing that.
im thinking i might be tuning with the slide closed. or myabe it was close. but. they say in the manual. tune at 1400 rpm. turning yoru pilot screw. then set idle to 1200 rpms. then if you have a racing biek they sometimes turn the slide down so when they wreck, it quits. well.. it says they do that. doesnt say they wreck or it quits.
and they say dont turn the mix screw after youve done this you can seize it.
so what am i doing? ive just down a leak down test and it didnt leak. sealed off everythign and no leaks. the only thing not tested, would be my new vacuum line, i thik does work when i suck on it, it doesnt leak air. and the rubber around the carb. one thing i sort of squish it a little, i use this intake. http://www.scooter-center.com/scowe...arget=productdetail&category1=A&category2=CAT
ive got another intake i could switch. i had to change the reed cage cause it leaked. so i switched to that intake. is a 23mm connection rubber too small? for a 25mm connection intake? the intakes not leaking aroudn teh base or anything. it has a rubber connction around it thats 23mm and the spigot on teh carb is 25mm. i sprayed starter fluid around the spigot on the carb near the rubber. didnt check around the intake and rubber. i tighten it a little too. cant think of anything else this would be.
the two videos. https://vimeo.com/44081952