# Valve Lash on 18hop Twin II (Opposed Twin) 422707-1214



## smata67 (Nov 29, 2005)

I understand that this is not an OHV. I see many procedures online for adjusting OHV, but how would I do this one?


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## usmcgrunt (Sep 16, 2007)

The valves are adjusted the same as any flat head single cylinder,only your doing it twice on the same engine.I included two links that should help you check the clearances and adjust if necessary.Use a file and not a grinder on the valve stems if you find the clearances to tight.A grinder may remove to much of the stem and then you would have to replace the valves and start over.Pay attention to the positioning of the piston at 1/4" "past" top dead center when checking.The section named "adjusting tappet clearances" will help you understand the setup.Hope this helps.

http://www.briggsandstratton.com/engines/support/frequently-asked-questions/Servicing the valves/

http://www.briggsandstratton.com/en...~/media/AA53F45A5DF74CD5A5CD2D0B5DCA17EF.ashx


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## smata67 (Nov 29, 2005)

It talks about what to do if clearance is tight, but what if it is too large?

Does this type of engine keep its tolerances well?


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## usmcgrunt (Sep 16, 2007)

If your valve clearance is to much,you could have a valve seat that is loose and moved upward,or there could be carbon build up on the valves or seats.One of the more experienced on here will hopefully have more ideas.


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## Don L (Jul 14, 2012)

If this engine has sat up for a long period there is a chance the valves are stuck.You could try a good penatrating oil on the valve stems and working the valves open and closed,but it sounds like you'll have pull the heads to diagnose the problem.It wouldn't be a bad idea,just to remove the carbon in the combustion chambers if nothing else.Most of the problems I've had with the valves on these engines have been with the valves wearing into the seats and causing too little valve clearance.


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## Morella (Aug 15, 2012)

If there is crud under a valve, or a valve is stuck, it will show up on a compression or cylinder leak test. Something that we used to do on aircraft engines was "staking the valves", tapping the valves gently with a hammer to try to loosen them up. A little penetrating oil might help as well. The nice thing about a leakdown test, vs. simple compression test, is that you will hear any leakage from the crankcase breather, carb, or exhaust, and that will tell you what isn't sealing. It's as simple as screwing an air hose adapter into the port. Some compression testers have a hose that can be detached for this purpose, but you usually have to remove a valve core inside it to make it work. Good luck!

-MM


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## sboricic (Oct 10, 2009)

I have the same engine on a old lawn tractor. If the valves are out of place, could that cause the engine not to turn over when I'm trying to start it? It has a good battery on it.


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## 30yearTech (Sep 14, 2006)

sboricic said:


> I have the same engine on a old lawn tractor. If the valves are out of place, could that cause the engine not to turn over when I'm trying to start it? It has a good battery on it.


Unless someone recently reset the valve clearance and took too much off the valve stem, then this is likely on the case on your engine. These engines are notorious for having starter motor issues.


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