Carby Keihin carb clone

[Jeffrey gagnon]

Ok so as far as idle what did you do cause mine either reved to high right around 3500-4000 or reved so low the bike would stall at times it would rev up to almost 7000 rpms and i would hit the kill switch to not cause harm the idle screw seems to do nothing and the air screw seems to do nothing as well

 

[SRPM]

I really didn't do anything at all. When I first started it kept trying to die so I turned up the idle screw (the biggest) and then screwed the smaller one in all the way in and screwed it out a quarter turn at a time and revving it up in between and letting it settle out to find the right idle. After I found the sweet spot I adjusted for the best take off because that is the starter jet as well(if i remember correctly). Check out that link and you'll have a better idea of how to set the smaller screw.

 

[SRPM]

http://www.iwt.com.au/mikunicarb.htm this isn't for this carb but it made me understand it a lot better.

 

[Jeffrey gagnon]

So after reading that yes your right does help you understand a 2 stroke carb so after reading went to try adjusting it i know have the c-clip on its richest setting as well as the air screw turned all the way in which is also at its richest setting so after doing some research and watching a good video which was on a dirtbike but was same issues i was having which makes me think i need a richer pilot jet and possibly a richer main jet once i get the jets ill do pilot jet first to see if that fixes my problem but the reason i say main jet as well is vecause that controls from 3/4 to full throttle which is where it cuts out and feels like theres a speed restricting device in my engine but back to the pilot jet no matter how much i adjust the air screw and idle screw she wont idle if i rev she goes up down trys to bog and die then i have to rev again so my conclusion the pilot jet is running too lean and i need one a little bigger once that gets done then i can see where im at as far as the main jet if its even necessary

 

[Jeffrey gagnon]

PS almost forgot one of the other reasons i think its the pilot jet is because if i use the choke lever she runs a little better also meaning shes running to lean so if i use the choke it richens the mixture

 

[skyash]

I got one of them carbys and no luck with eny of my bikes probably rong jet but I only got what come with it. It's in the carby bin with the Arthur one's. I tried every needle setting and turned the 2 screws in and out but no good. Looks nice

 

[Jeffrey gagnon]

You know what im truly baffled right now i set my c-clip to lowest setting did 1 and half turns out on air screw and like 2 turns out on the idle screw and for once she was idling it was a high idle of like 3800/3900 but still no top end can get it 25 MPH downhill only 21 on flat surface throttle cuts out at anywhere from half to full think i might need main jet i dont know yesterday was a bit colder today is a bit warmer so i will have to see how the warmer weather plays out

 

[SRPM]

Sounds like your running too rich. I re-drilled the jet down to .56-57 16mm #74 bit runs a lot better in the top end. I'm now hitting 30-31.7mph on flat surface and pulling strong up my test hill at 22-22.5 mph.
What is your oil mixture, could be that you have to much oil in your mixture and could be fowling your plug. I recommend 32:1 for brake in then 40:1 if I need to. I also recommend changing your plug to an ngk b8hs spark plug part number is 5510, I put the one in that came with the engine and it ran like complete dog poo

 

[SRPM]

Also if you have the high compression head like I do I would put it on and see if that helps at all.

 

[skyash]

I can get idle on all sittings but when I try to ride it goes then a bit to much throttle and cuts right out. To much to play with