Adjusting valves on HuaSheng 142F

dmopedMA

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Apr 14, 2017
Messages
171
Hello,

To get some background, here is my build: https://motoredbikes.com/threads/4-stroke-schwinn-stingray-chopper-occ.51001/

I've being riding my occ for few days and It does bug when I get to the high range RPMs (around 25-30mph), my first choice was trying to solve it with the "hidden" mixture screw, but after playing with it around, still the same.
I believe it's time to adjust the valves, I've seeing around the forum that .004" intake and .006" exhaust works for most of the users, but I would like to know what to expect when I open it up...

Anyone has a video os a picture manual of how to open up and close the valve compartment? does it have a gasket to replace after you open it up? glue? black magic?

Picture I believe it's interesting by @jhammondcpa:




Thank you all.



UPDATE: Here is the How-To based on the one written by @The_Aleman (https://motoredbikes.com/threads/how-to-adjust-your-gxh50-huasheng-titan-valves.38514/) but with some pictures:

-------------------

Your engine must be "cold" for this procedure.

1a) Remove the 4 bolts on valve cover with the 8MM wrench. Carefully lift the valve cover off the engine. The objective is to not stress the valve cover gasket.
If the gasket sticks to the engine, that's okay, just leave it there.
IMG_20180617_155719.jpg

IMG_20180617_160538.jpg


1b) Recommended: Carefully remove spark plug boot and then remove the spark plug with the 5/8" spark plug socket.

2) Now you have to find TDC on the compression stroke. If you're not familiar with each stroke on a 4-stroke, I've attached an image that should help. Take a good look at the valves while slowly pulling on the pullstart a few times. You need to adjust the valves when both valves are fully closed, and this only happens at Top Dead Center of the compression stroke. The valves are closed for the longest amount of time between the start of the 2nd stroke and the start of the 4th. Insert a straw into the spark plug hole and find TDC. The straw will be at it's highest point and there should be play in both valve rockers. If there's no play, they are set too tight.

4strokecycle.jpg



3) On each valve rocker there is a slotted stud with a nut on it. Loosen the nut on each rocker with the 8MM wrench. The rocker closest to the exhaust is the exhaust valve, and the rocker closest to the carb is the intake valve. Use the feeler gauge and the screwdriver on the stud (loosen the nut as needed) to set the clearances. A proper setting is when you feel a light drag of the blade as you pull it through the space between rocker and valve stem. When you have the clearance you need, hold the stud's position with the screwdriver and tighten the nut about wrist-tight. Repeat for other valve.

IMG_20180617_162321.jpg


4) Put the plug back in and the valve cover back on. Don't overtighten the valve cover bolts, they only need to be snug, about halfway between thumb-tight and wrist-tight.
 

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Frankenstein

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Jun 24, 2016
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5,078
In that area on regular vehicles often we just put black oil resistant rtv as the cams are all doused in oil, most repair manuals instruct just that with the type of gasket they recommend for those kinds of sealing zones. Usually you only very lightly finger tighten the parts and let the rtv cure for the time specified on the package, then torque down to spec.

Edit: Black magic would actually be a good pseudonym for that wonderful permatex creation.
 

dmopedMA

Active Member
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Apr 14, 2017
Messages
171
Thank you @Frankenstein for your tips, do you know if this specific engine has a gasket there? where to buy a replacement?

EDIT:
Sorry, I see that there is no gasket, the gasket is made out of the oil resistant rtv...

When you say "torque down to spec" do you know what is the spec for the 142F?
 

Frankenstein

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Every automotive manual I've read specifies the torque the manufacturer recommends for just about every single last bolt imaginable, so when I say torque to spec I mean look at what the manual says. In your case I've not read the manual, but since it's just a rocker cover something like 5-7 foot-pounds is usually appropriate, and a common figure in my reads.
 

Frankenstein

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Also since I forgot to answer that other question, the way you open a rocker cover is removing the bolts holding it down and using a special pry tool to keep within warrenty standards, however on something this this, and something like my own vehicle, a sturdy butter knife is a really nice tool that doesn't damage surfaces easily. You don't have guide pins on these tiny motors so it's difficult to screw up the taking apart phase, just don't be an idiot and jam a knife all the way into the rockers.
 

heligonka

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Aug 14, 2018
Messages
63
First of all, virtually all air-cooled 4-stroke engines require that their valves be set "Cold". Next, when the factory valve setting gaps are listed in the metric system, it is the baseline, and is best achieved by using metric feeler gauges. So when people who don't like the metric system get involved, and start giving out the "American" or SAE measuring system, they invent their own special valve gap settings (it is very much Obvious on this website) such as " .004" intake and .006" exhaust " they have chosen to ignore the factory settings (and the metric measurement) and become the gurus who know better. On the HS 142F engines the factory valve gap settings are .08 mm and .11mm, and there is no way on Earth to set those valves accurately by using "American" or SAE feeler gauges. (because there is no exact SAE equivalent to the precise metric values.) I have no argument with those who think that the factory settings are Wrong, that is their own little game, and they will play it. I purchased a set of metric gap gauges, and set my valves by them, and all is well. It is just a shame for all this simple matter of adjusting a couple of valves, to have a thousand different viewpoints that end up in such a muddle. Not necessary when basic math and mechanical certainty can tell it all.
 

Frankenstein

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Joined
Jun 24, 2016
Messages
5,078
First of all, virtually all air-cooled 4-stroke engines require that their valves be set "Cold". Next, when the factory valve setting gaps are listed in the metric system, it is the baseline, and is best achieved by using metric feeler gauges. So when people who don't like the metric system get involved, and start giving out the "American" or SAE measuring system, they invent their own special valve gap settings (it is very much Obvious on this website) such as " .004" intake and .006" exhaust " they have chosen to ignore the factory settings (and the metric measurement) and become the gurus who know better. On the HS 142F engines the factory valve gap settings are .08 mm and .11mm, and there is no way on Earth to set those valves accurately by using "American" or SAE feeler gauges. (because there is no exact SAE equivalent to the precise metric values.) I have no argument with those who think that the factory settings are Wrong, that is their own little game, and they will play it. I purchased a set of metric gap gauges, and set my valves by them, and all is well. It is just a shame for all this simple matter of adjusting a couple of valves, to have a thousand different viewpoints that end up in such a muddle. Not necessary when basic math and mechanical certainty can tell it all.
Yeah I never really understood people's need to deviate from what is basically a technician manual on the equipment from the factory, they already did the hard work figuring out what is exactly needed (because the dimensions between parts differ, and so the expansions between parts differ when the maths are done) so why actually deviate??

It's analogous to trying to use an sae allen wrench set when you are assembling metric parts, you can kind of make it work but it usually f***s up the tool or the product, and often both as desperation sets in, which usually only occurs when you stray from the manual spare rust and other special bullsh*t.

I won't pretend as if it's not possible to get away with it, I've done so enough myself to know that rednecking it is practically an art, but seriously if you have factory settings and aren't modding beyond a certain range (in this case you'd need to be heating those valves beyond a certain point to make it bigger, or under measuring and killing the thing) then using what it was designed for is the best route.
 
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