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Old Jan 11, 2008, 03:53 AM
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Joined Dec 2006
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OS .91 4 stroke valve adjustment

How hard is it and what do I need? Is there a kit available?
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Old Jan 11, 2008, 10:20 AM
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United States, TX, Weatherford
Joined Dec 2006
1,629 Posts
Not hard to do at all. You do need the feeler gauges, some small wrenches and a little understanding of the system. The valve clearances are the same for OS, YS, Saito, Magnum and Thunder Tiger four stroke engines. They are all poppet valve engines.

Do this job at room temperature. The engine needs to be cold or room temperature.

Remove the valve cover.

Slip the feeler gauge between the valve stem and the rocker arm.

Make sure the engine is at top dead center (TDC) and on the "compression stroke." The compression stroke occurs when the rocker arms are not moving and the engine is on TDC. TDC occurs twice, the second time is when the rocker arms are moving about.

The clearance is between .04mm (or .002 inches) and .10mm (.004 inches), the .10mm feeler gauge should be tight in the gap between the top of the valve stem and the rocker arm.

Loosen the locking nut and set the clearance and tighten the locking nut again.

Oil up everything when you are finished. I use afterrun oil, 3 in 1 or similar oils. Does not matter, the oil will eventually be expelled from the engine.

You should also download an "Operating Insturction" sheet from one of the manufacturers. The one I am looking at at the moment is from Magnum, it is a little better than the OS one, it has a picture to help you understand what you are looking at.

Good luck, take your time, you can do it. There is "no kit" but you can get feeler gauges at any auto parts store. I got a package of little wrenches from Sears, all different sizes.

Cheers,

Chip
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Old Jan 11, 2008, 11:28 AM
Tao Jones industrial ave.
Wisconsin, USA
Joined Apr 2005
168 Posts
O.S. Engines does have a "4 Stroke Cycle Engine Valve Adjusting Tool Kit" for sale. It contains two feeler gauges, a small box end wrench and a hex wrench. I think it cost 10 or 15 dollars. Tower Hobbies has them if you are interested.
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Old Jan 11, 2008, 07:11 PM
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Thx guys.
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Old Jan 13, 2008, 07:46 AM
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Here's a photo GhostRider32:
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Old Jan 13, 2008, 07:07 PM
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Thanks everyone.
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