How to Adjust Valves on OHV Small Engines (Valve Clearance / lash)



Video on how to set valve clearance or lash on OHV small engines, using a 14.5 HP briggs and stratton as a example, which it is basically the same setup on most engines, just some my have different size bolts or different type of lock screw. Thanks for Watching!

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36 thoughts on “How to Adjust Valves on OHV Small Engines (Valve Clearance / lash)

  1. Hey,
    I have one at the moment thats dragging while trying to start, Although the valves have been adjusted it is still doing this..So have come to conclusion that it is the cam advance..How is the best was to verify this with out taking the engine apart for you?
    Ive adjusted many valves but have never had this problem come up..so either cam..or I know on some could be the key way slightly sheared..out of time..
    Thanks!
    Bruce.

  2. Why does the decompression valve opening too wide cause the decompression valve to fail to decompress the power stroke ? Is it because at TDC of the compression stroke the bottom of the decompression valve strikes the top of the piston causing the decompression valve to snap shut before or just as the power stroke fires?

  3. Ok I finally took apart the engine on this Briggs 18.5 H.P. Intek Engine..It turned out to be the Advanced timing spring loaded mechanism had broke, thats on the cam itself with a spring on it….So if you replace the starter,The starter solenoid ,the Battery..All that you can think of, ignition switch..Just know the advancement on the cam can also be your problem..Makes it seem like weak battery..bad solenoid..and or connection..about 70.00 dollars and do it yourself with a gasket about 80.00 your good to go..This releases compression during the initial start..So just keep in mind that this may be your problem which I have seen no one mention this problem ..Your welcome!..

  4. I did a tune up on a 20KW Generac. On this Generator I tried to adjust the valves as recommended by the manufacturer. Felt the compression build ( with finger over the spark plug hole) when the piston reached the top. I used the feeler gauge I realized mine only went to hundredths instead of thousands. .02" instead of .002" But I figured it would just be a little noisy for the test. But it wouldn't start, and I figure it's either the valve lash is off, or there is air in the NG line from shutting it off. Have to go back to get it going. Any idea on your end from your experience ? Also, by rotating the flywheel to get TDC, I was told the direction mattered ?

  5. Hey thanks for showing this video. I learn o lot. I would like to ask you a favor. I'm going to adjust my lawn mowers valves is a briggs&stratton 20 hp engine. What's the filling gauge # for this engine?

  6. Briggs manual says PISTON 1/4" past TDC. Just turn engine where one valve fully opens and adjust opposite valve. Never had an issue like this.

  7. i've seen the valve cap missing on the intake in someone else's video also and questioned it. maybe that's correct? on mine the cap is on the intake and missing from the exhaust but i know somebody has been in the engine before me and may have swapped it accidentally. Obviously makes a huge difference in how far the valve is being pushed in.

  8. hey I really like your videos, very entertaining. When a mower doesn't work and all hope is lost then it fires up it really is like MAGIC!!! I have a craftsman briggs and straton 18.5 quit on me while I was riding it. flywheel turns, valves are fine, quik start does nothing, it gets a spark cause I got shocked twice…..any ideas?  thanx!!!!!

  9. I have a problem with a Briggs 14.5 OHV, the adjustment of the valves would not stay after being torqued down. I discovered (what is called in the briggs parts diagram) the valve keeper cap was loose and came off on the exhaust valve. Does this just snap back on or are there other parts that keep it on the valve stem? Thanks!

  10. thanks this is great. I'll grab a gasket and give it a go. Have the same over compression on start. Way better than replacing the compression release/camshaft.

  11. I have a honda gx240 8hp with OHV. Its an older pressure washer from 1989. I looked up the specs and intake=.15mm and exhaust=.2mm. The intake valve was already to spec. The exhaust valve tappet was way in, it has no play, no gap or anything. The motor was at TDC. When i put the exhaust tappet at .2mm clearance the engine became difficult to turn over, almost impossible. When i put the exhaust valve back in to where it was it works ok, but is hard to start and runs a little rough. Why is the exhaust valve tappet needing to be pushed way in at TDC?

  12. Hello, First off your videos have helped me so much! Thank you.. I have a 15HP briggs the Valve is really lose. But here is what has happening. After running it for 10 – 15 min smoke starts coming out not alot but enough. When I opened the hood the air fileter was covered in OIL and it seems has if it coming up throuh the carb into the filter. WHY is this happening?? could it be because the valves are so lose, which they are. Just wondering your thoughts. THank you Kindly Dev

  13. I have a 15 horse briggs that is hard to start. ITt will turn over ok and if it back fires once the next over it fires up. is that the valves?

  14. I have a riding lawnmower that I have been trying to fix for my dad. It is a craftsman 6 speed / 42 inch cut with a 15.5 hp OHV engine. Dad's lawnmower is doing the same thing. I have replaced the starter and the ignition coil pack and it still will not start. Do you think this valve adjustment is the problem? Also I really found your video very informative. Thank you Denise Brown.

  15. Great instruction! Thanks. My Briggs manual says that you should go PAST top dead center on the compression stroke by 1/4 inch and then adjust the valve clearances. I noticed you didn't do that. Does it matter much? My 28W707 Vertical shaft briggs won't start and backfires very loudly only, I found small pieces of gasket on the floor after that happened. Could I have blown the head gasket?

  16. I have a 22hp briggs & stratton Engine. when I pull off the right valve cover there isn't any oil in the cover while on the left, oil runs out when I loosen the valve cover. How to correct this problem?

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