posted on Nov, 1 2011 @ 01:29 AM
Mopeds are great fun if you modify them. It's very easy to do this to a 2 stroke engine.
The way we used to do it was cut the piston halfway down and smooth it off, also increasing the barrel inlet and exhaust ports by skimming off a few
millimeters. Also adding fibre racing reeds that flex more than the standard steel reeds. Most times al lot of the factory restrictions are in the
exhaust so at least you need to tear it open and try and hack them out (usually just simple bushes added during the final factory welding to make the
pipe thinner restricting the exhaust to bring the speed down to road legal requirements) or replace it with a straight through one with a larger bore.
This leads to much more exhaust noise which attracts attention but a proper racing exhaust silencer (I used one made by Fresco specifically for the
TY50) takes care of that without significant loss of compression. Sometimes you want that insanely loud exhaust noise though.
I owned a yamaha TY50, a small road legal trials moped. 49cc engine. Standard book speed was around 35mph, mine did over70mph and had a 'power band'
that could let you do power wheelies in 2nd at around 40mph. I could outrun 125cc bikes and cars with it. It was a weapon. Being a trials bike it was
even smaller and lower than other mopeds, almost looking like a childs motorbike. That was the coolest part, nobody ever expected to leave them in the
dust the way it did. It was the fastest moped around and was always just a 49cc without any rebores to the barrel. The most common way to make a mope
go faster is to bore out the barrel to increase the engine cc. Most 50's have room to be bored out to around 70, some a lot less. This is much more
expensive than the cut piston method which I think actually works better. The only problem is the life of the small end bearings comes down with the
increased revs on some engines. and the engine can get hotter than it was designed to. Anything air cooled is usually fine as the increased wind
velocity compensates for the extra heat. If you cut the piston too much it can also shatter due to vibrations.
You have to know what you are doing when you drive one of these, I'm serious. They can be so easily flipped or slide out or not stop in time due to
crap brakes. So many ways to get hurt. In most places these modifications violate the licencing conditions of driving them in the first place so you
are better not to advertise the fact that it's been modified to go faster. Cops hate this, and many times your insurance might be technically invalid
due to undeclared modifcations.
My friend owned a yamaha FS1E aka a 'fizzy' which was origionally a 49 cc 2 geared mope which did around 40. this madman tuned this thing and I think
he had an 80 cc barrel on it and geared for speed with a small back sprocket actually did over 80 mph. Actually made the brakes a bit lighter by
replacing the drums with disc brakes
Mopeds are far from dorky. Its so easy to make them go incredibly fast, just dont add anything that adds weight like upgraded shocks or brakes or
bigger fuel tanks.
edit on 1-11-2011 by angus1745 because: word error
edit on 1-11-2011 by angus1745 because: clarification of
wording
edit on 1-11-2011 by angus1745 because: grammar