bbk and pipe need some carb help!!

[7m-iata]

hey guys finally finished my new engine build and frame is now redone along with all the plastics painted etc. I installed a "matched" kit off ebay on my 1e40qmb (minarelli/jog clone) its a 47mm piston (73cc) kit I'm good on my top end so my main jet is good but it dies at idle and my pilot jet is basically maxed out. I've replaced all the gaskets/seals and verified that there is no vac leaks. I have to basically close the air bleed all the way to allow it to idle but when I do that I lose all midrange power and have to baby it up to about 20mph before it gets any sort of power. I have a 120 main (1.2mm) and a 60? pilot (.60mm) my issue is that the opening in the 19mm mikuni for the fuel from the pilot to enter the carb is a .60mm hole so even if I use a larger pilot it won't make any difference...
basically I'm asking is there any way I could drill the hole in the carb a little bigger to allow a larger pilot or is that going to mess with the flow of fuel at idle i.e. is it angled or chamfered?
Any help is greatly appreciated I'd love to have the power I know this thing is capable of while still being able to stop without shoving my hand over the carb to enrichen it lol

[7m-iata]

down jetted the main by .10 mm now I have no top end -__- tryed the fuel pin at all the levels seems to be working backwards as I lowered the clip raising the pin I lost more and more speed. I now have great low to mid range but right as the variator reaches its full extension I'm right under the powerband of the engine and it starts sputtering. I'm not getting any pops so I'm assuming the jet is really close to correct. Could this be a spark curve issue? I'm running a dc voltage kymco box but I think the stock kymco is lower compression than this engine with the bbk installed??

[patthesoundguy]

the hole for the pilot jet is to let air in to mix with a set amount of fuel that is metered by the jet. so if you are getting not enough fuel for that amount of air simply enlarge the pilot jet to meet your needs. You need to get a bunch of spark plugs and start doing some chops and get a cylinder head temp gauge. Go back to the previous carb settings that worked. And work from there with cyl head temps and plug chops. And by your description in the first post you just need a bigger pilot jet. there is a tutorial in the wikipreedia on how to drill a pilot on a spree carb, it has been done. you might just need a better carb to beable to swap jets out. open up the carb and take a pic of the jets and the carb as a whole and post it and maybe every one can give input on drilling the jet, or what carb might work.

[7m-iata]

I've already drilled the jet. What I'm unsure of it that the hole in the jet is at .60mm and the hole that is casted/drilled into the carb itself where the fuel that enters the carb for idle it also at .60mm. I may be wrong, but should't that mean even if I enlarge the pilot it will still only draw as much fuel as the .60mm pilot due to the hole for the fuel to enter the carb only being .60mm?

[bakaracer]

The hole in the front is for the air fuel screw metering hole. Don't mess with that.

[bakaracer]

Drop the pilot down. A 60 is way to big for that 19mm mikuni. Should be around a 45 if not smaller. Or you got something plugged in the pilot jet system or major intake leak

[7m-iata]

no leaks every gasket/seal is brand new and I've checked every one of them with carb clean while running. The pilot might not be a "60" size but it is a .60mm which by looking at the way they gauge sizes through mikuni would probably be like a 40 or 45. I'm not talking about the front hole, if you were to take the throttle slide out of the carb you would see the hole for the main/pin then directly behind that you can see the hole for the pilot almost looks like this O. the "O" being the main and the "." being the pilot. It is an air bleed carb so your not adjusting fuel with this carb your controlling the mount of air to go "unmetered" basically. (I deal with fuel injection in my line of work so thats the easiest way for me to explain it)

[bakaracer]

So the carb your using is a vm looking carb that doesn't use the short vm jets ?

[7m-iata]

yeah I guess, but I got it figured out I wasnt getting enough fuel supply from the tank, pulled the line off and it was dribbling out not pouring out as it should. I fixed the flow problem and got it tuned pretty good, but I guess it had too much POWAHHH!! lol because then I found a hidden secret D:< aparently the P.O had an issue and welded the output shaft to the output gear because the press fit let go and I managed to snap all the welds /:

[bakaracer]

Oh s h i t !!! That's not good! At least got a lot of those parts around online

[7m-iata]

I have another full engine that I took the bore kit and pipe off of. it has a broken starter gear boss so my buddy never ran it. For the tie being I just rewelded it but did it the right way unlike the small tack welds that were on it before it'll work to get me from point a to b then back to a to pick up the extra egine tomorrow. Rolling burnouts are fun d: gotta get some clutch springs and variator weights and get this thing really going.

[deuce217]

Cool looking bike, any more pics?

[7m-iata]

I have a build thread here viewtopic.php?f=16&t=25357

[7m-iata]

Found out I had the wrong plug in it the whole time -__- my fault, but oh well. I installed the new plug it was a night and day difference. Got it tuned perfect even with the long stretch it wants to lift the wheel when it hits 3 mph (clutch springs??). BUUUTTTTT I believe my carb might be too small ): I just can't get the revs out of it like I should be able to the carb just won't flow the cfm the engine needs at that speed. what size is good for a 73cc? I've read alot of people say 20mm then alot of people running the malossi kits are running 24mm okos I can get my hands on a 24 mm mikuni for a good price at the local scrap yard. It'll need a rebuild but thats nbd just wondering if its going to be too big? Thanks

[bakaracer]

Unless your running a kit that is designed to make 17hp+, no need to go bigger on the carb. A 17.5mm carb for those motors can support up to 15hp turning 12.5k rpms. So keep that in mind.