I read dozens of articles, watched numerous videos...actually got it started a couple times! But for some reason, I just can't seem to get "adjusting the valve lash" right. I did it a couple times, and it worked. Now, it seems to be getting worse.
First Question: I think I'm at TDC: both valves closed, put a screwdriver loosely in the spark plug hole, rotate the top of the motor until the screwdriver is pushed out as far as it goes. There are two times when the piston is at it's highest mark and the valves are closed - how do I know which one is the compression stroke?
Second: When I rotate the motor so the piston moves 1/4", do you move it clockwise or counter clockwise? (Is CW and CCW from above looking down, or under the blade looking up?) Should I see a valve move?
Each time I mow, I need to adjust the valves - that not right either. I should adjust it and be done for a year, right?
What am I doing wrong?
Thanks,
(from the middle of what is quickly becoming a jungle)
Nic
#2
nplsdvr
Update: I'm 100% positive I'm at TDC. I put my finger over the spark plug hole and when I feel pressure build up, I know I'm on the compression stroke. That mystery solved.
Assuming that you are properly adjusting the valves at .003-.005 IN and .005-.007 EX, and are having repeat problems, and they valves are staying at the proper clearance, it is starting to sound like a faulty compression release mechanism on the camshaft, Camshaft replacement is the next step.
if you remove the engine to examine the camshaft, just go ahead an replace it while the engine is torn down.
Did you check the studs to make sure the rockers are not being pushed out, requiring you to reset them each time. Had that problem more than once on OHV design.
I always set my valve clearances a 1/4" pasted TDC on the compression stroke, to make sure that the compression release does not come into play. After I set the clearance, I rotate the engine by hand at least 4 complete cycles and recheck the gap. Are you sure that you are tightening the lock properly when you complete the job and then recheck the clearances.
#7
pugaltitude
There was issues with certain model OHVs that the cam lobes wore out and you would need to check clearances often as the gap would be wide and not allow starting.
Also Rivets is it not on the power stroke!! :thumbsup:
Did you check the studs to make sure the rockers are not being pushed out, requiring you to reset them each time. Had that problem more than once on OHV design.
I remember seeing that on a youtube video - studs are fine.
#10
nplsdvr
o.k...time to come clean.
The short story: it works. I got it started.
What I did, in order to save myself some time (plug, try, unplug, reset, plug, try, unplug, reset, etc.) I didn't attach the spark plug wire. I figured, if it didn't rotate past the compression stroke, what good is that extra step? Well, guess what I discovered (what you already know, I'll bet.) It seemed like the motor was stopping at the beginning of the compression stroke, not 1/4" past TDC - but just for the heck of it, I hooked up the spark plug. Lo and behold, it fired right up.
I guess I was adjusting it correctly and my assumption was not a valid test.
Thanks for the input, guys. I double-checked everything you told me to check, so I definitely learned more. And my own lesson taught me the most.
