re: valve clatter
Dear Future Andy,
This is Past Andy. For the second time in your life, you made the embarrassing mistake of not remembering that the crank goes through two revolutions for the cam to go through one revolution.
In other words, when the crank is in a certain position, the cam is in one of two positions. When the crank/pistons are on TDC, the cam makes the engine either at the top of its compression cycle, or the top of its exhaust cycle.
Don't set the valves (or the timing for that matter) like the engine is at the end of its compression cycle, when it's really at the end of its exhaust cycle.
Remember that.
Yours Truly,
-Past Andy
BTW: After setting the valves like a mechanic instead of a monkey, my xs400 is back to sounding like a purring vicious animal. I love it.
This is Past Andy. For the second time in your life, you made the embarrassing mistake of not remembering that the crank goes through two revolutions for the cam to go through one revolution.
In other words, when the crank is in a certain position, the cam is in one of two positions. When the crank/pistons are on TDC, the cam makes the engine either at the top of its compression cycle, or the top of its exhaust cycle.
Don't set the valves (or the timing for that matter) like the engine is at the end of its compression cycle, when it's really at the end of its exhaust cycle.
Remember that.
Yours Truly,
-Past Andy
BTW: After setting the valves like a mechanic instead of a monkey, my xs400 is back to sounding like a purring vicious animal. I love it.
posted by veloandy at 9:23 AM
2 Comments:
hey, i just did a valve job as well, and it sounds like my valves are very loud....however i did follow the procedure laid out in the service manual, wait until the intake valve sinks, then rises, then rotate to the tdc mark for that cylinder, and you should be in the right position...
however, i ran into the same problem, felt like i had zero valve clearance,and now they are loud....so what did i screw up?
Hey Nate,
The crank rotates twice for each cam rotation...
I bet you're 180 cam-degrees (or 360 crank-degrees) off...
Pull the valve inspection cover, and turn the crank until it indicates TDC. If the clearances are where you set them, turn the crank 360-degrees to TDC again, and the clearances will probably be super-loose.
When you get the engine turned so the crank is at TDC and the clearances are super-loose, re-adjust them.
When possible (and when I don't blow it), I like to look at the camshaft when adjusting clearances...when the crank is at TDC, the rocker arm is either on the heel of the cam lobe or the nose of the cam lobe. If it's on the nose, Rotate the crank 360-degrees. If I remember right, the cam is kind of hard to see on an XS400, but might be visible with a flashlight in the other inspection cover.
Good Luck!
-Andy
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