# 21HP B&S Motor OHV Valves Setting



## willie (Jul 17, 2008)

Hi everyone,how are y'all doing?
I need some help resetting the OHV valves on a (Husqravna YTH 2148-21HP-
B&S Motor# 385777-0349-E1) riding mower.
The on-line Web shows different ways of setting the OHV B&S valves.


THANKS, willie


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## OptsyEagle (Jul 17, 2007)

Is that a twin cylinder motor. Your specs should be intake 0.004" to 0.006" and your exhaust should be 0.004" to 0.006"

First you remove the valve cover. Then remove the spark plug. Now turn the flywheel clockwise, by hand, and observe the movement of the valves to determine which one is intake and which is exhaust. (usually the bottom is the intake but make sure). When the piston is moving on the compression stroke, place the rubber end of a pencil in the cylinder hole onto the piston and observe when the piston is at top dead center. Now make a mark on the pencil and another mark 1/4" above it. This is just to measure the movement of the piston inside. Now turn the flywheel so that the piston is 1/4inch past top dead center (roughly. You are just ensuring that both valves are fully closed).

Now I like to measure the valve lash before and after adjustment, so do that now. If either needs adjustment, take a torx screw driver and loosen the lock on the hex nut. I think a 10mm wrench turns the hex nut. Once the lock is off, place a 0.005" feeler guage into the intake's valve lash and turn the 10mm wrench until the valve is very snug against the 0.005" feeler guage. Jiggle the rocker arm if you have to. Once set, tighten the torx screw to about 4 ft/lbs. Do this for both valves. I usually turn the flywheel a couple revolutions and measure the gaps again.

Once the valve lashes are set rotate the flywheel again and keep a very close eye on the intake valve. What you should see is that as the motor moves onto the compression stroke, the intake valve will close fully. As you keep rotating the flywheel slowly you should see a very small bump in that valve. If you do, then you know your compression release is working and with the valve lash set, she should start up just fine. If you don't see it, give starting it a try anyways, but you may have a camshaft failure and unfortunately that is more difficult to fix. I bet you don't. Valve lash adjustment is basically regular maintenance and if it has never been done for a long time, it is probably due and will probably fix your problem.

Put the valve cover back on and put the spark plug back in and try it again.

Here is a video to help if you have never done this before. Different motor but everything is pretty much the same, except perhaps the specs.

https://www.youtube.com/watch?v=hGkn0jR9RJM


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