xs650

[pinstripe_chuck]

when im putting on the timing chain i line up the mark on the stator to put in on TDC, but which cylinder should be on the compression stroke when the mark on the cam is up.

I assume it will be the left one but i just wanted to be sure.

 

[shaas]

I could be mistaken but I don't believe you have to worry about that as the cam determines compression. That is what timing marks are for.

 

[JDS1]

I'm no expert either but isn't both cylinders on the compresion stroke? I thought that one of the vibration issues had to do with the cylinders operating in unison. Rephasing is the answer to this I believe.

 

[Kingwj]

I'm no expert either but isn't both cylinders on the compresion stroke? I thought that one of the vibration issues had to do with the cylinders operating in unison. Rephasing is the answer to this I believe.

The cylinders move up and down in unison but they fire 360 degrees apart. When the left cylinder is rising on compression the right is exhausting spent gases. You can look at which points set is opening on the stroke to determine which cylinder is firing, the crankshaft cannot make this determination.

 

[angus67]

even though both pistons rise ad fall in unison, when they are at tdc, one is on compression, and the other has the exhuast valve open for exhale.
but yeah, thats what the marks are for. line it up, and the cam does the rest

 

[grizld1]

Right you are, shaas; the cam controls valve events. And since you're dealing with a 360* twin with a cam turning at 1/2 crank speed, it wouldn't matter if you installed the cam 180* out (timing notch down), except if the bike has breaker point ignition. In that case you'd only need to move the points leads from one coil to the other. All this stuff makes more sense if you remember that a 4-stroke cylinder fires every second revolution of the crank.

 

[pinstripe_chuck]

yeah once i got to thinking about it, it seemed like a dumb question. It was that damn clymers manual that confused me, it said the make sure the cylinder is on the comp. stroke but didn't say which.
Thanks guys.