What is involved with boring a carb out 1m? Is it a even 1m around from the center? What about the slide opening? Surely the cutaway will be enlarged also. Won't this lean it out?
If you go too far the slide will leak.
There is keyhole boring and taper boring in addition to just centering the id and boring it straight through.
Different applications seem to respond to different approaches.
What are you looking for?
I have a modified 134 cyclinder. I want to bore the carb out to 37m from 36m. I have no idea regarding the different boring techniques you mentioned. I work in an automotive plant and have access to a rather large machine shop area. I was hoping for one of the machinists to do the work and not be down for a couple of weeks sending the carb out. I am sure they have the equipment to do the job. But i need to tell them what needs to be done.
First of all if you wanted a 37 mm carb and you have a 36 you would only be removing a 1/2mm of material all the way around the bore. It is measured by diameter not by radius.
Second I dont think you can bore out some Mikuni carbs becuase you cannot takeout the needle jet<nozzle or whatever it is called>.
The slide of your carb is going to be a limiting factor. I dont know how close you can get but one thing for sure is the bore of the carb cannot be bigger than the dimension of the slide. The machine shop should be very helpful on giving you ideas and advice on that.
I believe keyhole boring would make the carburator an oval instead of round. I could see this being very advantageous to keeping the stock carburator size feel at 1/2 throttle and below, with a little bit more airflow past 1/2 throttle.
although I woudln't be no where near an expert on this I believe my statements are kinda common sense.
tell you what though if I had access to a machine shop like that I would be buying all sorts of junk carbs with the same body as yours and buying the guys at work lunch once a week just to play around with different ideas.
I have a 36mm carb of a 00 kx 125 that was bored to 38mm / 39mm oval. looking at the carb the hard bit is boring round the areo foils at the rear. the jet stack in center can be removed . The problem is matching front and rear of the carb because of this.
Weve done this also un a rod hone machine and made heart shaped bores . You could go 37 or so on that Kaw . I also tried extending those ribs for more of a scooping affect to the jet area to try to get better signal for better throttle response .
i think you cant just bore it out, because you wil chance the intake radius angle. and you wil get a bad flow.
i think you can better buy another carb, i like the keihin pwk's but i dont know if i sould take a 38 or a 39mm (ktm standart on sx). for my tuned yz125.
Sorry to upset you symen but the slide is the widest part of kx carb. I boutgh a 36mm carb of a 99 kx 125 only to find it was a 36mm carb bored out. I boutgh a new carb only to find I only neede the throttle body.(now I know) A new carb cost (£290 +VAT). Luckily I found a second hand for £85.