Wednesday, September 14, 2011

What are the basics of setting the valve cam timing?

I have a Honda parallel twin motorcycle (CD200 Roadmaster) and i recently took it apart to change the cam chain. I cant reach any repair manual. how on earth do i set the timing of the valves? i got two dots on opposing ends on the camshaft sprocket. Do both the cylinders fire together in parallel twins? and all the valves do not close together at any point on the cam. hence im in deep water someone help me please ill be forever indebted to you. thank you.What are the basics of setting the valve cam timing?
The pistons rise and fall together since it has a 360' crank. It also has a single over head cam. Even better yet it has a single set of points driven from the end of the cam.

So set the engine at TDC. Install the cam and chain so one cylinder is in the over-lap position. That means both valves are just barely open and if you turn the engine a little one way, one valve will open more and the other will close. Or if you turn the engine over the other way the opposite will happen. The manual say don't turn an engine backwards but for this measurement you can get away with it this one time. If the engine turns over some then it feels like the piston is hitting something don't force it you are way out of time. And the piston is hitting a valve.

Now adjust the valves to speck. When one cylinder has its valves in over-lap %26quot;TDC exhaust%26quot; you set the other cylinders valve clearance and visa versa.

Since both cylinders fire together you dont have to worry about getting the spark 180' out. Just set the gap then the timing.What are the basics of setting the valve cam timing?
You line up the dots at TDC. Both cylinders fire alternately.What are the basics of setting the valve cam timing?
If both pistons are at top dead center at the same time, the valves on one cylinder should be closed and the others in overlap. (both valves cracked open or the lobes pointed down towards the valve stems. At that point it would be in time between the cam and pistons. If both plugs fire at the same time, the engine should run. If it has a twin cam system it would depend on the timing marks (indexing of the cams) Mercedes had an engine that one side of the engine's cam timed 15 degrees (I think) later than the other one.
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