zerorev3rev4

that looks awesome

possibly pilot jet blocked , or spark failing at low rpm

at a guess the engine does need to be earthed to frame via the mounts and coil to frame you can check this with a voltage type car tester the type with the dial , turn to constant polarity ( buzzes when testing wires touched together ) and check for a buzz in between motor and frame and frame and coil body also earth the plug body

dont know how someone could miss that , but then again ive heard of lads missing pistons out in tank engines , there were 12 though so maybe they got a bit sick towards the end

i use to run atf in mine ok , i replaced clutch plates springs and cable which made clutch much nicer

fuel tank is prone to damage or wearing through on underside from memory

i thought that aswell like a mid range jet or inbetween ,, it is a dellorto isnt it ?

The difference in size shouldnt cause the problem you have it sounds like its blocked especially if adjusting has no efect

did you clean carb out properly

possibly 12 to 14 maybe a little less but no more

is there enough space for a ball ,i think you need to look at a parts manual , but personally it doesnt look like there would be enough space and the markings left on the pusher dont look as if a balls made them as it would have a shiny indent in the centre

Try removing frame side vents and plastic in front of fuel filler to gane access

good chance the rectifier has gone

when should it fire , are the parts standard

What plug are you running .drop needle by 2 to make up for lifting it what does spark look like on new plug when problem occurs

try dropping needle and lean off pilot circuit as could be rich to start with ( hard to say without hearing ) but Stator could be getting weak when warmed up causing weak spark

what size do you have

its a ty not a yz if you want summat to flog about tracks get an mx bike

is there free play in the lever

no vacuum would cause hard pedal with little travel and no fluid leak unless servo was filling up which would take some doing

was fluid low on first inspection , has fluid been contaminated , determine what leak is and why , is clutch hydraulic and fed from brake reservoir ? try clamping rubber flexes to rule calipers / cylinders out , does it have abs { not sure if c15,s ever had abs ) , could servo be rusted through or has a bake pipe corroded through along bulk head

is it from something else that has been in the van poss building related

the bolts in my hub are right hand thread if you look inside the hub theres no space for anything to be any larger than the stud , ( i dont think ) could you drill in the inside to get some wd40 in the back also a good few wacks squarely on the end with hammer to get some shock through it can help

are you in uk ? might pay to send stator cdi and coil altogether to be checked maybe west country windings

i think the lack of response means that most folk are in shock that you have gone from a 4rt to a sherco , 70 to 1 should be fine , and check the bike fully after every ride for fallen off or broken parts