[oreo_n2]

My KTM 560 is making 70 PSI... is that low?
(its got an 11:1 compression ratio... i dont know how to relate those two numbers!)

[TLRMan]

Originally Posted by oreo_n2

My KTM 560 is making 70 PSI... is that low?
(its got an 11:1 compression ratio... i dont know how to relate those two numbers!)

It means that the swept volume is 11 times greater than the total volume of the head and cylinder with the piston at TDC.

Does it have an automatic decompression device? This will show it low.

OK.....hear you go....
The piston sweeps up and down inside the cylinder from Top Dead center (TDC) to Bottom Dead Center (BDC). The distance it travels vertically doing this is known as the "Stroke" of the engine and this is determined by the length of the crankshaft throw. The volume swept out is known as the "Swept Volume" and this is the capacity of each cylinder. Above the piston at TDC is the volume contained in the cylinder head gasket and combustion chamber - this volume is called the "Clearance Volume". Each time the piston goes through a cycle it compresses all the fuel air mixture sucked into the engine into the clearance volume before ignition takes place.

The volume of a cylinder is calculated by multiplying the area of the bore of the cylinder by the stroke.

Bore Area = Bore x Bore x pi / 4. then multiply this by the stroke (pi has a value of 3.14159) or Pi "r"(radius of bore)squared x stroke

COMPRESSION RATIO
The compression ratio is defined as (Swept Volume + Clearance Volume) / Clearance Volume

[oreo_n2]

yes it does.

i also tried dumping some oil in the cylinder and redo-ing the test. then it was 130 psi.

so then i dumped the oil.

and the bad news got worse... LOTS of metal bits and pieces of bearing races.

D'OH!

[TLRMan]

Originally Posted by oreo_n2

yes it does.

i also tried dumping some oil in the cylinder and redo-ing the test. then it was 130 psi.

so then i dumped the oil.

and the bad news got worse... LOTS of metal bits and pieces of bearing races.

D'OH!

Too much oil!
You may have hydraulic'd the engine.......You gotta take it apart now....and look for bent rods and stuff too

[oreo_n2]

oh no it wasn't too much oil. i only used a touch. the metal bits are all from when it popped on the track. the broken stuff wasn't much of a surprise.

[TLRMan]

Originally Posted by oreo_n2

oh no it wasn't too much oil. i only used a touch. the metal bits are all from when it popped on the track. the broken stuff wasn't much of a surprise.

OH! OK....
still gotta take it down though.....OUCH!