New Top End, Upgrade To 65cc's

46mm bore DR racing cylinder drops right onto the express engine case

here is the New aluminum piston

Complete gasket set comes with the cylinder kit

Start the project with a COLD engine and unbolt the exhaust at the cylinder, then remove the fender bolt, loosen the exhaust spacer bolt at back of engine but do not remove it, let the exhaust hang there

Here is the combustion chamber( inside of head ) after removal from the engine This is the way it looked when I removed it ,only one small carbon deposit that washed off with carb cleaner

the engine with the head off ,there is a thin layer of carbon on top of the piston

the cylinder has been removed , the piston is still on the rod
some of the old base gasket is still on the case

old piston has been removed : LOOK CLOSELY YOU WILL SEE THE OIL FROM THE CRANKCASE this engine is getting proper lubrication

The old base gasket has been cleaned from the case, and new piston has been mounted, ready to put the cylinder on

I also sanded the edge/seam in the case where the two halves meet

The new cylinder is on and the head bolted down ( after cleaning the exterior fins with a wire brush before mounting it )
use a tourqe wrench set for 8 ftlbs and tighten in a criss cross pattern
I removed the autochoke because i am using a 1977 carb with manual choke

here are the new cylinder and old cylinder side by side
the old cylinder is very clean on the inside surface and is reusable if needed
The Intake port of the new cylinder has room to be opened up ( that is a future modification)