from my understanding you seem to be getting slightly more than just normal blowback if the things spraying it over the motor... you did say youd expect something...
as yank says, tis piston ported. at certain rpm there will be a lot of backspray. at other rpm, there wont be any. nature of the beast.
firstly. you jet the motor for performance, not backspray minimisation. ill forgive that, this once
what the
is 0.025 inches?
jets are one thing that is measured in MM. dont quote that. some are measured by flow rate. blah blah
(and if you measured your jet as being 25.4/1000x25... lemme see now... oh no. 0.635mm. thats pretty normal after all... would be a 65 jet
down to 24 thou would give you 0.6096mm or a 60 jet. pretty standard. imperial drills can be handy for getting those "in between" sizes.)
now. how certain are you that its the backspray?
overflow on that carb feeds into the airfilter too...
normally, if its overflow is an issue, floats are too high or stuck.
and normally, in this case, the engine will flood.
flood as in half your fuel tank will drain into the crankcase and the thing wont turn over until emptied out...
you dont mention this happening so i can either assume this isnt the issue or you turn your fuel tap off all the time.
meh. a dooozy
pull carb apart if you havent already, make sure its guts are in order.
sure its not a leak elsewhere? fuel line, gaskets...tiny lil leak and youll end up with an oily motor pretty quick.
my $4.50 worth. pay up to purser