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Scooters - 50cc => zx50 => Topic started by: Blacky on August 08, 2010, 11:54:03 PM

Title: KB is the off road version of zx
Post by: Blacky on August 08, 2010, 11:54:03 PM
Hello and thanks for a great forum  :)
i have found this forum and its great fun to read about kymco models. i own a KB (same as zx but with off road tires), its the same scooter, both models share the same frame engine parts and variator. i also own a B&W 250.
i have installed on my KB (zx) the following: big bore kit, rear pully 2000 rpm springs and tourqe spring, open air filter and a larger main jet (actually the original jet was drilled), and iridium spark plug. i will install a quicker variator soon. all electric parts have been refreshed to new ones.

since the installment of the big bore kit the idle rpm is not reducing on stop after an intense ride. i can get the performance parts rather cheap since i am in good relationship with my mechanic. he claims that i need to lose the open filter and install back the original air box. since i lost the original air box and i need to buy a new one just for trying solving this rpm issue, i prefer to invest my money on something else for my scooter. but its really impossible to keep on riding like that since on every stop light the scooter is extra jumpy.

can anyone give me an opinion what to do next?
thanks  ::)
Title: Re: KB is the off road version of zx
Post by: thebatman on August 09, 2010, 12:05:14 AM
what up? welcome to the forum.....i had a similar issue recently, my return to idle sucked, took forever..the mix screw needed to be set at 1 turn out, then adjust idle according to your taste...fixed it right there.....if the scoot wants to jump, the idle is off or your fly springs are getting weaker....hope any of this helps...post back any results.......
Title: Re: KB is the off road version of zx
Post by: thebatman on August 09, 2010, 12:11:57 AM
oh yeah blacky...if you have changed all that..NO WAY put that oem box back on..youll restrict the scoot again and be wasting that money from mods..what exhaust are you running?? yours definately needs to breathe now...who makes the kb??  kymco??
Title: Re: KB is the off road version of zx
Post by: Blacky on August 09, 2010, 12:43:59 AM
Thanks Bman, i will try following your advice first thing tomorrow morning. can you please advise me which of the carb screws is the "mix" screw? i know the idle is tuned with the top screw on the carb isn't?

KB is made by kymco, same scooter as the ZX. my scoot is a year 2000 model (yep totally old).

the weird thing is that the idle rpm goes wild only after riding for few miles. after start and when the auto choke is turned off, idle is tuned perfect.

still runing with the stock exahust. i have made sure its in good condition and not cloged with burned oil.

i have been thinking about installing a bigger carb and a new exahust to complete the modification. can you write what adjustments have you done on your ZX?

Title: Re: KB is the off road version of zx
Post by: art on August 09, 2010, 01:01:02 AM
  Hey blacky welcome to the forum your crazy idle is most likely the air idle mix is to lean. It should be the only other adjustment usually a little left of the idle set screw,not familiure with the 2000. But turning in ritchens it and out leans usually.
Title: Re: KB is the off road version of zx
Post by: thebatman on August 09, 2010, 02:18:20 AM
yeah, turn the mix screw, that should fix it, (thanks art..lmao)..smaller one under the bigger idle screw..have you drilled any holes in your exhaust or beaten out the catalyitic converter??...wordslinger drilled 6 3/8 holes in his pipe..i had cut a hole,beat out the converter, welded back up on my oem exhaust... dont think i have ever seen a kb..cool.. my mods are slight: upgraded tires, unrescrited(boss drive,cdi)..adige clutch(4 now,have motorio to put in) w/1000malossi contra, 1500flys..race var from s.a on ebay(heavy as hell)w/7g rollers(4 now,thinking 6.5), technigas next r chrome exhaust, shaved head for squish, open filter w/rejetting.(made my own jet,around a 94).....have polished belt cover, chrome grips, integrated eruo turn signals front/back,red running/speedo lights,removed stickers..i think thats all... next list is: port reed cage till i get one, port exhaust(pay someone for that job..lmao), then bout a 17mm carb i guess..advoiding bbk for now anyway, want a bad stock..lmao 
Title: Re: KB is the off road version of zx
Post by: thebatman on August 09, 2010, 02:22:00 AM
i cant believe your getting by with the oem carb anyway, if you have a bbk on that..yeah, get a bigger carb/exhaust..the technigas is a good one but ppl say the technigas rs2 is better(is bigger, for 70cc+ bbks).. z is running a 28mm carb on his zx(many more mods than i..lmao)..shaka has a 19mm on his...
Title: Re: KB is the off road version of zx
Post by: art on August 09, 2010, 02:53:04 AM
 Some of the older kymco's have real honda type carbs,may be ok. the 2000 peoples have the real deals you can like set the neddle and everything  ;D
Title: Re: KB is the off road version of zx
Post by: thebatman on August 09, 2010, 02:55:52 AM
did not know that...i need me one of THOSE carbs...lmao ;)
Title: Re: KB is the off road version of zx
Post by: art on August 09, 2010, 03:28:47 AM
 yep I think word and dru have them.someone does on a 1999 and a 2000. Was talking about the carbs and shim trick and they had no clue what i was talking about  ;D
Title: Re: KB is the off road version of zx
Post by: thebatman on August 09, 2010, 12:37:14 PM
lmao...i didnt either.  ;D   ;) wondering if I should try it... :D
Title: Re: KB is the off road version of zx
Post by: art on August 09, 2010, 06:54:58 PM
 It may help your just off idle pick up.
Title: Re: KB is the off road version of zx
Post by: Blacky on August 09, 2010, 10:39:27 PM
Wow, thanks for your replies guys its warmimg my litlle kymco's heart. i didnt try changing the mix screw yet, i am delying it for the weekend, i am using my other scoot this week due to longer distance rides. i will be posting the results here..

reading all the modification on Bman's scoot caused me to start making a wish list :)

i have drilled only one hole on my stock exahust. for Bman: did you "open up" the exhaust and just took everything that was inside out? (catalytic converter) making the exhaust all empty inside before wellding it back?

i know the original weight of the rollers is 9g, when installing a race variator what will be the rollers weight that i want for me to achive a better take off rather then better top speed? i am using this scoot in city limits only. i didnt understand if you have mixed rollers or not  8)
on ebay i see race variators for the zx that comes with 9 or 8.5g included in the variator set.

i wish i was in the states, its such a hussle to modify my kymco here in israel. can you belive i need to pay extra tax plus a certificat from the official goverment offices (something similar to DMV) for every vehecile parts over 50$ when reciving a package from e bay! we dont have a lot of stores of race parts here.

p.s: is it really possible to change the speedo light to red (or blue)? i just need to open the plastic covers? is the color determened by the color of the LED only?

thanks a lot everybody  ;D
Title: Re: KB is the off road version of zx
Post by: art on August 09, 2010, 11:04:26 PM
 You can make it any color you want with the right paint   ;)  I forget the recomended one.
Title: Re: KB is the off road version of zx
Post by: wordslinger on August 09, 2010, 11:41:22 PM
..i cut my exhaust open, cut out the cat-con...and part of the baffle..welded it all back up...

..i now have drilled the holes in the bottom and that was the best thing i could have done all around, to my exhaust, other than replace it...


Title: Re: KB is the off road version of zx
Post by: thebatman on August 10, 2010, 01:18:19 AM
man, thats crazy about those extra taxes...damnitt man...maybe you need to try and find used parts..lmao yeah, i had did the same as wordslinger but i had to actually beat some..lmao  hammer and a chisel..    my oem weights were 8.5..i would try some 7.5 in yours..i have 7s at the moment but its not right,maybe 6-6.5..... if you order a race var, i dont know if id get the same one i have.(scooterassasians)?  vt cycles in honolulu has one im thinking i shouldve gotten...    yeah, i just bought red bulbs and placed inside for runners and speedo..parts store has red,blue,green, sometimes you can find purple, never tried painting them as art said tho..........glad to help...im still a newbie on these things..lmao  this forum and ppl here made all the difference......wordslinger, art, sid, zombie and shaka to name a few(still missing BOTH of those guys too)..
Title: Re: KB is the off road version of zx
Post by: wordslinger on August 10, 2010, 01:18:59 AM
..actually, i wish i had left th' catalytic converter alone...

..i get an occasional backfire at low speed deceleration ever since i cut it out...

..very annoying...

..and  the cat was never really exhaust restrictive, once i got a good look at it...
Title: Re: KB is the off road version of zx
Post by: wordslinger on August 10, 2010, 01:22:07 AM
zombie and shaka to name a few(still missing BOTH of those guys too)..

..where th' hell are they..


..  ??? damn...


 :-\
Title: Re: KB is the off road version of zx
Post by: thebatman on August 10, 2010, 01:24:52 AM
i know, right.....damnitt man........after i had spent a needless 3-400$ in the begining to figure out why she didnt run, my converter was clogged up, slap full of oilish residue, carbon, i had to take mine out...lmao fired right up then too.....
Title: Re: KB is the off road version of zx
Post by: wordslinger on August 10, 2010, 01:26:05 AM
..mine was mostly clean...brown, like the firing ring of my plug....
Title: Re: KB is the off road version of zx
Post by: thebatman on August 10, 2010, 01:42:28 AM
my carbon problem couldve been building since THEN.....i doubt the shop even looked when the rings were put in..... shheeeee is waaaakking uuuup!!!!....rlmao