Plug fouling saga

hi all,thought i had everything sorted but more problems! vespa px200e running 115 main jet,1/2 turn out of mixture screw was producing a nice looking plug and running great,last night stopped dead on me,kicked and kicked and waited then kicked but not even trying to start,pushed it 4 miles home and had a look this morning,took a lot of kicking but with both mixture and idle screws all way in it went,changed screws to previous settings,tried it,still pulling great and running well,but when cold takes a lot of getting started? also should air filter be wet or dry? it seems mine is getting wet with what smells like fuel?as far as i know standard crank and i have not drained all oil but from filler plug it looks clean(no white milky colour)when its going its going great but very hard to start,any attempt to richen mixture or increase jet size results in engine not running so well,bogs down etc, any ideas anyone? thanks

I recently had a similar experience, had perfect running engine with
beautiful tan brown coloured spark. Was just pulling away from home and
about few streets away suddenly engine cut out… tried to kick start
and roll start nothing…changed plug and re-gapped and fired once then
stopped. Check everything, fuel, electrics, etc. Came down to a shonky
ignition system.

I progressively replaced each part of the ignition system till it worked, ended up replacing everything. I unscrewed the HT plug cap and found that had unusual amount of resistance, so replaced that. On the HT lead I cut it down slightly as I noticed that one end had corroded. It was a black colour. Don’t cut too far back otherwise won’t reach far euongh from CDi Box to sparkplug. Cut long story short, then replaced CDi Box and STILL didn’t fire up then replaced Stator, I noticed a faint burnt smell around coils and there was a black scroch mark on the back of the stator [:(], replaced that and it works now perfectly [:D]

A way to check a healthy spark is to take the plug out and connect it to the HT plug cap and touch a side to the crankcase to earth it, while you kick it over and u should see a spark coming from the plug as you kick the engine over, the spark normally produces a gentle crackle.

Hope that helps. Sorry about long post

hi and thanks for the help, i should have mentioned except it did,t occur to me at the time the spark was there and it was a good spark,as you said a gentle crackle of nice blue sparks,it starts easy when warm its just when cold and the petrol in air filter was a worry as i read something about clutch side seals or the crank causing this? i suppose there are so many symptoms for similar problems.