How to derestrict the Kymco ZX50 Super Fever 2 stroke

[yajblackburn]

Here it is.  There are two that I am aware of.  I have performed both of these on my 2004 ZX and the result is a top speed of 50mph.  The first one is the variator.  I purchased a complete race variator kit (weights, ramp plate and face plate) from VT Cycles for around $60.  I never tried to just replace the boss drive and leave the stock weights to see what happens.  The bike might not move right with a derestricted boss drive and stock weights, I'm not sure.  It did work on the People model though so who knows.  So after the variator is replaced, the next restriction is the CDI.  You cut the light green wire comming out of the CDI unit and splice it into the dark green wire comming out, thats it.  The results went like this.  Bone stock = 30mph, CDI modification = 37mph, aftermarket variator = 50mph.  I still use the original stock drive belt which has 11,000 miles on it and absolutley no problems. 

[sthomas904]

I found an ebay store in The UK that ships to the US and they have Unrestricted Exhaust, FULL POWER CDi BOX, racing coil. Now I haven't ordered these parts so who's to say they actually work

http://cgi.ebay.com/RACE-COIL-for-KYMCO-ZX-50-Fever-Scout-People-50-125-150_W0QQitemZ300291564779QQcmdZViewItemQQptZUK_Motorcycle_Parts?hash=item300291564779

[yajblackburn]

I've heard that the free flow exhaust only works well on the bike with an aftermarket bore kit rather than the stock cylinder.  I've heard that it's only good for a few mph on stock, maybe 3mph.  I don't think it's worth the investment of a couple of hundred dollars for a louder bike and a few mph.  The CDI can be modded by splicing two wires together, I don't think you need to purchase a race one as it will have the same effect as doing it yourself for free.  As for the race coil?  Not sure, I honstly don't think it will make any improvement over stock.  Maybe someone out there can prove me wrong?  If your going to invest money to make it go faster, the first things I would do is by a bore kit with the exhaust and airfilter.  You will have to re jet the carburetor to make up for the more fuel it needs.  I don't know of anybody who has done these mods, so I don't know the performance gains.  It might only be 5-8mph, 10mph max.  Thats a costly modification too, all that money for an extra 8mph is kind of steep.........but that's just my opinion.

[OtoHNS]

When I pull my CDI out, I only see a dark green wire coming out.  Where's the light green one?
The electrical section of the manual doesn't seem to describe a light green one either...  Am I missing something?

[Shaka]

The green wires are right next to each other.  The light green one doesn't connect to the harness.  It just plugs into an empty slot in the plug.  I just took a splice connector and jumped the two together.  When my bike was stock it bumped me from about 38mph to 44mph on the flat.  Downhill it allowed it to rev up higher so I got about 48mph.    It still would only do 38mph downhill before. At this point I have done a big bore, exhaust and 19mm carb and am still running the stock (derestricted) CDI, but now she screems!

[OtoHNS]

Thanks Shaka. 

I'm curious.  Besides the big bore mod, which of the mentioned mods helped with acceleration most (not top speed)?

[Shaka]

I did all of the big mods at the same time.  I think that putting in lighter roller weights will have the biggest impact on accerleration though!  Stiffer clutch springs as well.  I think the rollers will make the biggest difference right off the bat.  I don't know how much of an impact the two have by themselves, as I did both at the same time.  I did change rollers to slightly heavier ones for a bit and it really hurt my acceleration.  So, I think that just doing lighter ones would have the desired effect.

[OtoHNS]

I must have a slightly different version of the CDI as I only have 5 wires coming out of the CDI box and only one green one.  It's exactly the same as its described in the Italian-English version of the owner's manual that is floating around.  Which makes me wonder if my scooter is a non-US version.

Having said that, I'm still not satisfied with the max speed of 30 mph so I'm going to try some cheaper mods besides re-cleaning some essential parts (carburetor, oil injector) etc..

I see some relatively affordable parts on ebay which I'm also thinking about getting, i.e. race variator, race coil, race CDI, possibly race clutch and springs.

[Shaka]

That's strange!  Mine has the # TYC-D421 on the front of it.  It has 6 wires.  Otherwise, it sounds like you may have something else going on as well.  Mine did a good solid 38mph stock.  I think that the dealer took out the washer between the the two variator halves previously though.  That may be the difference.  I still have the stock variator, but with lighter rollers in it, and I guess minus the washer also. 

[OtoHNS]

So I've concluded that I've got the derestricted CDI.
The only reason why it's so slow (30 mph) is because I think the variator/clutch/belt needed some TLC.

I opened the case for the variator/clutch to find a TON of worn down belt particles and a little rust here and there.
Today, I replaced the old variator with one I found on ebay for $33 (including shipping).
Immediate improvement - perhaps a little better acceleration and increased top speed from 30 mph to 35-37 mph.

Next will be new clutch springs, perhaps new clutch compression spring, and if that doesn't work, maybe just a whole new clutch.
Also coming will be a new drive belt and power coil.

I'll post any improvement in performance each step of the way.
Replacing a variator/clutch is much easier than I thought.  10-15 minutes is really all it takes with some tools.

[OtoHNS]

Another quick update,

Replaced the ignition coil to one I purchased on e-bay ("race ignition coil") and the spark plug.  It was appalling to see that the old spark plug tip was almost completely rusted.  I wonder whether any of the former owners ever even touched it.

Performance changes?  To be honest, I don't think so.  Maybe a tad bit smoother early acceleration?  But more likely just my whimsical wish.

So what's next?  Drive belt and clutch springs.

[Shaka]

Lighter rollers if you haven't already will improve acceleration also.

[nickybee123]

I got a weird issue I wanted to ask some advice on - I got my parents a 2007 Kymco ZX-50 (I assume it's the Super Fever though it wasn't marketed as such in Croatia - it looks like the Super Fever I see on google images though)...anyway I bought the thing as a present for my dad to use and he loves it - but when go to croatia for the summer I think it's slow as a snail....I keep reading about how it can be tweaked easily so I wanted to enquire about this (btw my own scooter - in California - is an SR-50 Ditech with performance pipe and lighter rollers/tighter contra spring)

Anyway - the boss drive has been replaced but other than that - that's it - the dealer says no CDI de-restriction is needed on this bike - I printed out the pages I found through this forum describing the light green wire etc etc etc...but he said "not needed on this bike"

I think he's a bit clueless...

So I tried to find the CDI (download that english service manual from the italian site) and the thing is I dunno what I'm looking at...I opened the battery compartment and took out the scooter battery and I found a few things connected in there - but I really don't know what I'm looking for - anybody got a picture of ths stock CDI with a shot of the green wire...

hopefully the picture will allow me to complete this exercise myself

That aside I think I need way lighter rollers (scooter is a dog from a standstill now) - and possibly aftermarket variator/pipe..

Is the pipe worth it ?? variator I can get for $38 or so including shipping.

If I do put in a performance variator how much will that add - like 3mph  top speed and that's it ?

As to the CDI -destriction - has anyone done it with an inline switch (just wanting to make when the yearly road test happens (they test scooters for modifications here) I can turn off the CDI derestrict...

Thanks guys

Nick

The first one is the variator.  I purchased a complete race variator kit (weights, ramp plate and face plate) from VT Cycles for around $60.  I never tried to just replace the boss drive and leave the stock weights to see what happens.  The bike might not move right with a derestricted boss drive and stock weights, I'm not sure.  It did work on the People model though so who knows.  So after the variator is replaced, the next restriction is the CDI.  You cut the light green wire comming out of the CDI unit and splice it into the dark green wire comming out, thats it.  The results went like this.  Bone stock = 30mph, CDI modification = 37mph, aftermarket variator = 50mph.

[zombie]

You have to take out the seat well to get the cdi. It will be mounted on the right side in a rubber strap.It is on the frame rail just in front of the ignition coil. The Light green, and the dark green are on the cdi,so you remove the cdi, splice the wires together leaving the dark green attached to the plug w/ the light green attached to it. I have replaced all the transmission parts w/ malossi, 70cc technigas pipe, delorto carb,k&n type air filter, malossi 70cc bore kit, and kenda 130x60 rr-120x70 ft. I get a verified 65-67 mph,and approx 45mpg. when it's running...

[nickybee123]

that's retardedly fast...I dunno if I would trust the stock brakes...they seem kinda crappy even at 65kmh - not to mention mph

however I'm glad you finally pointed out that I have to take out the seat well. After some (slightly) more careful skimming of the service manual I think I found the relevant page for that anyway - not sure how I missed it the first time.

Will do that in a few months when I'm next in croatia - anyone found a suitable switch for this - so I could turn it on and off - given that it's just a mechanical circuit breaker it can't be a very complicated switch...

hmm -just looked and it seems like it's kind of a pain to do correctly via a standard switch...e..g something like these - http://www.wiringproducts.com/contents/en-us/d88.html

does the light green wire have to be spliced into the dark green or can it just be cut ??

If it can just be cut that's easy because it means a SPST switch on the light green wire will do the job of turning the de-restrict on the CDI on and off...

but if it has to be spliced then I guess I just have to manually Un-splice it once a year before the inspection

I'm thinking I will just do the CDI first - then the variator - then a pipe and after that if I'm still not happy I can do BBK etc...

What weight rollers are you using btw - (do you happen to know what the stock ones are - I weigh 220 and I wanted to get some lighter ones)

Nick