zx50 with Taiwanese 80cc upgrade and 24mm PWK

[Quintin79]

Hey all

i recently bought some Taiwanese parts from ebay, the quality is decent and they were cheap as.  this is my first build so i was happy to go cheap while i am learning in case i break something or get the wrong part.

Cylinder Kit
http://www.ebay.com.au/itm/330899005635?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649#ht_1502wt_931

Carby Kit
http://www.ebay.com.au/itm/330901615725?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649#ht_1368wt_1163

everything fit together quite nicely and i am able to get the scoot to run - WOW the power increase is incredible! it goes so hard!

But i am having a problem where after riding for a little while (2-3 mins) the scooter dies and needs a few minutes before it will start again.  i have a strong feeling it is running out of fuel and right now i am thinking its because i am using the original vacuum valve on the fuel tank, and possibly im not getting enough vacuum when the throttle is open so the valve is shutting off.  i cant think any other reason. 

So how do you guys run your upgrade PWKs - do you replace the vacuum tap with a standard tap?

also i am still using the standard jets that came with the carby - any advice on what size jets i should run?

thanks in advance!

[twhit]

sound like you need to get abigger jet what size is in there now? I'm doing the same thing you are will be fireing up in a day or so. mine came with a 105 jett

[Quintin79]

thanks for the reply!

im not sure, i havent looked.  i reckon that if we bought the same kit, its likely we have the same size.

what is the purpose of the jet?  could it stop the flow of fuel to the carby from the tank?  i thought they determined how much fuel went into the engine from the carby.  if that is the case then the scoot would not have died completely and then taken a few minutes to restart?

[twhit]

do you have 2 hoses coming off the gas tank 1 if fuel and the other is vacuum for the fuel pump, the jet is set by size and is give fuel to the engine, if it is cuttingout wile riding you might need a bigger jet

[Quintin79]

No its not needing a bigger jet, the engine wasnt starving - well it was but the carby was starving first.

what i have done so far is replace the vacuum fuel tap with a standard brass barb i got at a local hose fitting shop (Enzed in AU) which has allowed the fuel to flow freely without any complications.  i also added more fuel to give it more hydraulic weight.  i was doing my testing with 1 litre at a time which could have also caused problems.  also added a clear filter so i could see flow.

We think that the problem was either with not enough vacuum from the inlet on this motor when the throttle is open, or a faulty tap.

anyway i am now getting continuous rides without starvation and am onto tuning the jets.  will keep you updated with results of jetting.

Jetting/Tuning so far

my 24mm motoritec flatside PWK carby came with a 105 main jet and a 45 pilot jet.  the needle has markings that say PW24.  most information out there seems more geared around the 3 letter standard in sizing and as far as i can tell there is no clear comparison.  this is just a standard needle for this carby.  some say that the first step is put in a JJH needle so that is what i will do

the scoot has incredible top end power and if you keep the revs up it runs great.  but it is very bad off the line or at idle or 1/4 to 1/3 throttle.  it dies, coughs - you have to keep playing with it.  we are going to work on the fact that it might be too rich so first step is looking at a larger diameter needle and/or a smaller low speed pilot jet.

i have ordered a selection from scootRS.com ranging up and down from the current jets and needle in the carb.

Some good tuning guides are here, ill be following them closely

http://www.duncanracing.com/TechCenter/KeihinCarbJetting.pdf

http://scootrs.com/tech.cfm?tip=tunecarb

[twhit]

I'm doing the same as you, my scooter is acting the same @1/4 throttle. I,m waiting for my jets,i'm going a 95 main and a 45 or 42 idle jet

[Quintin79]

my idle jet is a 45 and main is 105.  the main shouldn't be the problem.  reading the guides i posted above it is likely the needle, idle jet or mixture.

i have received my jets and needles but i wrecked my stator plate trying to remove the variator and now i have no spark.  stupid mistake so im now waiting for a flywheel puller to try and repair it.

i am going to start with a new needle - JJH.  visibly it is different and seems to be the most common that people use.  it seems to have more meat down low so im guessing less fuel.  ill try that first, and then try the idle jet.

[Quintin79]

So I dropped in a JJH needle and a 42 primary jet and its sharp and tight off idle.  Plenty of power now i can play with main jet.

Now the other problem is back where the carby is being starved of fuel again after a few mins riding.  I am convinced this is a needle and float problem.  I need more input flow

[twhit]

Just waiting for my stuf to come in. What is your mix raito ? 50/1

[Quintin79]

im running 25:1 as advised by autotech355 but its pretty rich.  actually to be over cautious i i made it even richer like 20:1 during run in phase.  ill lean it out over time.

[Raindrop]

so curious why did u change ur pilot jet ?

i run 120 main .. plenty ! .. 45 pilot about 1 and 1/4 turns ... put a bb yes a bb in that stupid power jet line .. trust me

after ur so called break in .. run 45/1 ratio ... dont get full synthetic oil get semi .. we dont have lc bikes .. i use lucas ..
run 93 gas or lower no turbo blue runs like sh** with oil

remove oil pump .. plug it .. seal it .. pep boys 4 bucks

racing throttle a plus 20 bucks all metal guts .. f*** plastic

2 k clutch springs stock clutch

racing variator .. 5.5 grams i run

racing exhaust ..


Do all this stuff my friend and trust me u push 65 mph .. but my 0-40 fast as hell


im about to buy a lc super 9 .. im done with the air cooled i want 90 mph

[Quintin79]

so curious why did u change ur pilot jet ?

because it ran like sh** with the 45 and runs perfect with the 42

i run 120 main .. plenty ! .. 45 pilot about 1 and 1/4 turns ... put a bb yes a bb in that stupid power jet line .. trust me

what is a bb in the powerjet line?

[Quintin79]

raindrop what are your specs?  are you running 80cc bb kit and a 24mm pwk? 

what needle are you running?

[Raindrop]

top speed 60 mph .. but 0 -40 ... amazing ...

48mm bbk 80cc -- pushing like 10 rpm red line on good day .. just wait to i bore it and the 52mm wesco piston kit .. and port intake to thin walls =]

ps .. the make water cooled kit af18 bore kit  now but get ready to spend around 600.00 in parts. dont come with radiator

24mm oko power carb .. 45 pilot 125 main need in middle clip set ..  40/1 oil ratio - if u look there is a a line on carb  one hose to 2 nipples .. stick bb in middle .. u dont need that .. there is no point ...  makes carb easy to tune .. crabs are a bitch just saying have fun some carbs dont have power jet .. just saying

racing throttle with pro taper grips.

v8 racing pipe
racing variotor  i think 6 or 7 grams not sure

racing clutch .. came with springs takes off at 3,000 rpm

about to add super 9 rear shock ..mmmm sick trust me makes look better

umm oil block off kit ..i mix own gas trunk hold 1 gallon in trunk  can perfect

im adding purple neon lights next week .. cops will hate it  .. f*** them

i just ordered black carbon vinyl for all plastic ... 


Kymco zx fun scooters to mod .. but once u get one u want a liquid cooled bike trust me way more balls =]

[thebatman]

Do all this stuff my friend and trust me u push 65 mph .. but my 0-40 fast as hell


im about to buy a lc super 9 .. im done with the air cooled i want 90 mph



90?...LMAO.... your funny... No offense homie but uhhhh, it is not happening... I own 2, see my threads.. 63gps'd was the best...
65?  onna zx?.. without gears?... naaaaaa...