Another stupid question

#1
Hey everyone well as my journey into learning about small engines continues I have another question that I would appreciate an answer to. I purchased a stage 1 performance kit for my gx200 clone and the kit comes with 18lb valve springs as well as a timing key. I'm planning on installing these myself and have seen a few tutorials that have given me a fair idea on how to do so only thing is I don't know what these parts honestly do.
So there's to valves (exhaust and intake) right? What exaclty do the springs do? And why is a heavier spring a boost to performance? How do the valves work as well?
The next head scratcher is the timing key? What's the function and how would it improves performance?

Sorry if these are face Palm worthy, I just felt the ethical need to know what they do before I try change them haha.
Thanks everyone! This place is a crazy good resource for help!
 

chrisr

Active Member
#2
In simple terms--Most small 4 cycle engines will have one intake and one exhaust valve. The heavier valve spring allows you to run a wilder cam (more duration and valve lift) and run the engine to higher revs without floating/bouncing the valves on/off the valve seats; which depending on the motor the valve may be open when it shouldn't be and the piston will make contact with it... The adjustable timing key allows for timing changes, where advancing the cam will allow for more low end, whereas, the default timing tries to give you the best of low/high end power. Cam timing can make a few more ponies, but if not done with care can also cause more problems and meltdowns.
 
#3
In simple terms--Most small 4 cycle engines will have one intake and one exhaust valve. The heavier valve spring allows you to run a wilder cam (more duration and valve lift) and run the engine to higher revs without floating/bouncing the valves on/off the valve seats; which depending on the motor the valve may be open when it shouldn't be and the piston will make contact with it... The adjustable timing key allows for timing changes, where advancing the cam will allow for more low end, whereas, the default timing tries to give you the best of low/high end power. Cam timing can make a few more ponies, but if not done with care can also cause more problems and meltdowns.
I see, so is replacing the timing key worth doing?
Or just valve springs and cam work?
 
#4
Graphic depiction of the four-stroke cycle, including valve springs, follows. Unlike this diagram, however, your clone engine has just one camshaft located down inside the crank case and operates the valves through pushrods and rocker arms instead of pushing directly on the end of the valve. The valve springs in your motor work just the same as in the picture. When you have it all together again, turn the engine through slowly before you put the valve cover on, watching the valve springs closely to make sure they don't bind. There should still be some daylight visible between each coil when the spring is fully compressed.

Offset timing key? That just makes the spark occur a little earlier before the piston gets all the way to the top on the compression stroke. Advancing the spark like that is generally better for high speed running. Just try it and see if it makes a difference.

Have you already or are you planning to remove the governor from this engine? Most people recommend a billet flywheel for your safety and a billet connecting rod for the engine's safety. Use the search feature to see more on that topic.

 
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