Should this be happening

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wbilotta

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I'm new to the kart scene and I'm just learning about the Briggs 5hp 130202 engine on the kart I was given.

After doing some reading I pulled the head off to have a look around. I noticed I can spin the intake valve when it's seated even when the engine is at TDC on the compression stroke. I can't move the exhaust valve when it's seated. It appears the intake valve is not fully seating and maybe I'm losing some compression because of this ?

I used a compression tester on the engine and I'm getting a smidge over 4lbs. Does the valve stem need to be ground or would I grind the part the valve stem rides on ? I'm not sure of the terminology of this part. The part I'm referring to sticks up thru the bottom of the valve chamber and the bottom of the valve rides on this part.

Thanks for any suggestions.
 
freakboy

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if it runs it runs if not take the valve cover plate off and take a look at the push rod and the valve spring.
 
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wbilotta

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The engine does run. I measured the clearance between the valve stem and the lifter and I have .004 on the intake and .009 on the exhaust which is in spec.

I'm curious as to why I can spin the intake valve when it's seated but not the exhaust valve. I would think the spring pressure would pull the valves closed thus preventing them from spinning....
 
freakboy

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i dont think so just open the valve cover and see if its the push rod thats pushin on it.
 
Kaptain Krunch

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Thats the compression release... Thats also why the compression was so low, you cant do a accurate compression test on one of these engines.

Once it gets going the valve will fully seat, its just so that you dont have to fight all the compression of the engine while starting.
 
EagleTalons

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Holds valves open longer. If you want, you can grind a little more valve lash in there. Give it a little more compression. Also, the intake spring is smaller than the exhaust by quiet a bit.
 
Kaptain Krunch

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You know, im really no sure exactly how it works haha.

i just realized something though, its the exhaust valve that is opened slightly right before TDC, not the intake, are you sure the valve that spins is the intake?

Im assuming this engine has compression release, but you know what assuming does...i may be wrong.
 
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wbilotta

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Kaptain Krunch said:
You know, im really no sure exactly how it works haha.

i just realized something though, its the exhaust valve that is opened slightly right before TDC, not the intake, are you sure the valve that spins is the intake?

Im assuming this engine has compression release, but you know what assuming does...i may be wrong.
Click to expand...

Yes, I'm sure it's the intake valve thats turning. This kart sat for two years and I'm wondering if the intake valve spring was compressed the whole time if the spring is worn out.
 
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