MY ZX50 O.E.M CARB TUNING

[thebatman]

so i guess im not gonna know whats to far untill i am to far.. i really dont want to go from "sugar to sh**" as some may say. especially since its still an oem carb..

[zombie]

It's almost always gonna happen like that. But you do need just a bit more.

[thebatman]

ok then, so just go back into and go up one more size. i think that bit measures .965mm(.038in).. thatll be going from a .914mm(.036in).   do i want the whole shank brownish from a plug chop??  i thought just ring was colored in.

[Shaka]

Sounds like you are getting close!  The whole plug will not change color until you ride it more than just for a chop.  That's why once you think you have it, ride it for a couple days and check back.  You may still need to go up to the next size from the sound of it.  It won't hurt!  Ride that for a day or two and check it.  Like Zombie said, use solder to close it back up and re-drill with the .914mm.  I've never tried it myself, but I hear it works!  Figure you're this far in, might as well learn to make 'em smaller too!

[thebatman]

what up fellas.. well, sinve i have several agreeing opinions about going up one more size, guess i should try it out today.kindof nervous tho in case its to big..lmao... todays my short day, be nice to ride a bit an test her out. hadnt from yesterday either.  i did recheck chop plug(4 sh**s an giggles) it doesnt seem to be as brownISH as yesterday, seems more tannISH now..

[art]

If it's been wet and humid while testing it will be a little richer may explain the color change,but your in the right range,one more up! I say,You still have an extra jet to start all over again Ha!Don't be scared,you'll be happy when you know its right and performing at it's best.

[thebatman]

well, heres my daily update:  drilled out jet to next size(.965mm)(.038in) from the(.914mm)(.036in) started fine, went on chop test, spit and sputtered most of the way, when she wanted to hit "overdrive",starting spitting badly. she was slower also.. mix ring was black, curved part was creamy again. now i gotta figure out melting solder to go back one....

[sidthesloth]

Ok, so you know where your limit is now. Soldering is not hard, I think zombie heats the jet in an old saucepn, I don't have that as an option so I just heat it with a regular soldering iron, $7 from the cheap shop. Give it a try and you will see it is no biggie.

[art]

Now if you could find a .935 bit.I use a self starting torch(bernzomatic)Heat jet one dab flux core solder to hot jet should do it,It would be nice if you could find another bit in between the two.Damn was hopeing it would not be to big a jump,as sidth has said now you know

[thebatman]

ok, im back... i did it, i did it... did i mention i did it??..lmao  whew!!!. it took me two times but i got it.. too much first time, had to drill, then melt again.. i cant really tell if the same as yesterday/today.. seems to be the same. idle still takes a min to return to normal but cant change idle jet.. guess i better run this for a day or so, sh** i cant go bigger..lmao. i did put a chop plug in for a small ride, bout 15-20mi.? the plug shank was starting to get a rustish/brownish color, the curved part of the electrode was also,rustish/brownish..... yeah, if i could find one i may try it,the .935?.... i was disappointed tho.. oh well.. sid, all i did was put a small piece of foil on the stove, sat jet on it..i actually had some thin solder

[zombie]

Well that's perfect bat. I'm proud for you. You can open the pilot the same way. It is tougher because of the length, but it can be done. I do the same as you w/ the solder I just set the jet on the electric ring itself. No foil or pan, and it has never stuck or left a permanent mark. But anyway sounds good to me. The .0935 may be the sweet spot.

[thebatman]

i couldnt have done any of this w/o all of you...ty btw....would like to have a 15-16mm carb, figure 17+ would be overkill with the stock cyl...on my original carb, i had taken the pilot tube out and bored it also. i had cleaned tube and the 4 cross holes in the tip.  i would have no clue as to what to even look for trying to open it up,  did you only do tube or 4 holes also?

[art]

Ha! sound like your there maybe you reemed it out a little bigger 

[zombie]

Actually a 17-19mm carb would be GREAT on your scoot. More air/fuel=more power. I run a 28mm that most will say is too much but I found it to be perfect. I have almost no sensitivity to environmental factors, and I have almost zero carbon build up. The inside of my pipe is still shiny if I wipe it w/ a dry rag. I really have no ideas on opening the pilot tube. The 4 holes are called atomizers. they draw air that displaces the fuel into a mist. If you opened only them you would draw less fuel thru the jet. I have never tried but MAYBE blocking 2 of the holes will draw more fuel, or at least keep it more liquid (dense). It is worth a try in my opinion.

[Shaka]

Congrats on making your jet!  If it is rustish color you're probably good.  I don't know if I would mess with boring out the pilot or the atomizer!  Those things are so small to begin with it would be very difficult to make small adjustments too!  Have you tired backing out the mix screw a bit more to help with fast idle/lean condition?  It sounds like you got your main jet figured out now.  Get a couple days ride on it and check the plug again.  Once you're satisfied with it you can really dial in the idle and mix screws.  Then you should be done!  Yay!!!