zx50 fever 2 stroke. carb problems ?

[steve w hebburn]

hi, re, the zx, £40 project !  possible carb problems?. having been off the road for 10 years. i have cleaned the jets,& blown thru the carb with a air gun ( 24ltr compressor)   removed& flushed fuel tank /pipes. fitted new plug,air filter, fresh fuel,2 stroke oil, and the scoot starts 1st kick ( starter  relay u/s) then after a minute or 2 the revs go up& down , and it stops.( sometimes will bog down when trying to rev it,)with quite a bit of blue smoke . most times it will not restart .unless its left for a couple of minutes. possible bystarter ?  carb jets ?  or replacement carb. any advice guys. thank you. steve.

[CROSSBOLT]

Gravity tank, vacuum actuated fuel shut-off valve sticking shut or something in the fuel supply toor on the carb. Fuel tank, tubing, vac. fuel valve, tubing, carb, float valve, main and idle jets then intake. In that order, start your search.

[steve w hebburn]

 hello & greetings from england !  thank you for your fast reply. and for the info. going to run a direct feed from a motorcycle tank to the scoot carb, to see what that does. then  will start the work you suggest over the weekend.  best wishes. steve.

[CROSSBOLT]

Good test! Hurry up! Am holding breath to hear what happens.......

[steve w hebburn]

hi, the sealey  1 litre portable motorcycle fuel tank arrived.  filled it with fuel, rigged it up diirect to scoots carb with new fuel pipes. ( blanked off carb vacuum pipe) still exactly the same problem.  runs ok on electric choke,until it warms up then revs slowly drop until engine cuts out. !  then i removed  carb, cleaned out float chamber ( a bit dirty) cleaned jets again, set pilot/ mixture screw 1 & a half turns out,( as per kymco info) now idles for 4or 5 minutes. revs still up & down a little, but  better than before. cuts out now & again but at least starts 1st time with a kick. cant take it out on the street to give it a good run as  it  has no vehicle ( roadworthy test) certificate, or road tax.. still think its got to be the carb  ! ! seen  new complete carbs on ebay @ £18.  its now 8.30pm gonna have another go at it tomoorow. best regards, steve.

[CROSSBOLT]

You will probably have to clear the passages in the carb as well as the jets. Ten years you can bet the passages are plugged. I do not know what restrictions you face but carb cleaner where the carb parts except rubber and plastic stuff is totally submerged for a time then flushed with water, then BLASTED out with air. Then I will bet it will work!

[eamartin]

Cleaning these carb passages can be difficult.  On my Super8 50 2T I cleaned it numerous times with carb cleaner/dip basket setup (nasty chemical).  The carb still did not function quite right until I used the ultra-sonic cleaner as well.  The passage carrying fuel through the small jet up into the carb throat makes two 90° turns so it's impossible to see straight through or to get a brush through there.  Clean it. Blast with compressed air.  Repeat.   

[steve w hebburn]

hi, yes, i think the carb is no good. 10 years off the road has been too long. removed carb from scoot ( the zx50 ) have cleaned everything again. new o rings, carb cleaning spray,air jet clean, still got problems.  i give up with this zx carb !  will post results when i buy & fit a replacement. otherwise my big hammer is gonna bash it. ha ha. only joking ! regards, steve.

[steve w hebburn]

hi, scoot is running ! bought a replacement carb( from a daelim 50) exact match, from a bike breaker. only £ 10. just over $12.  cleaned jets with carb cleaner and air jet. now for a derestriction variator sleeve, a free flow/sports exhaust. thanks very much guys for your info & help. regards, steve.

[CROSSBOLT]