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Post by pwr2wh8 on Apr 3, 2011 1:44:02 GMT -5
been reading that valve noise is fine and actually better than having tight valves. however, how much tapping is too much?
does any have a good video/audio clip of a tap that is within reason versus a tap that is bad for the motor?
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Post by Bluefront on Apr 3, 2011 4:52:27 GMT -5
Question without an answer......too much for me, maybe not enough for you.
The only way to resolve your problem correctly......get out the tools and adjust your valves to specs. Around .004" the tapping noise should be almost inaudible.
The problem with listening to sounds.....totally dependent on the microphone used, the other noises the engine makes, the distance from the engine the microphone is placed, any background noises like wind, your own speaker setup, etc.
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Post by scottish1 on Apr 3, 2011 10:05:27 GMT -5
I've learned an awful lot about valve adjustment on gy6 motors. First of all to address your concern.. When your valves are too loose, they don't just tap, they clack clack clack. A lot of clacking is frankly not good, it puts a ton of excess wear on things in there. When valves are tight, you only hear pretty much just the chugging of the motor. It is proper to hear just a little bit of tapping sound (not clacking!) when valves are adjusted correctly because too tight valves will burn the valves up. Once you adjust your valves correctly you will notice the difference immediately and here is how to do it.
Of course the valve cover must be off to observe the tappet arms. This is not only the easiest way to adjust valves, it is the way valves are adjusted for racing and for proper (high) performance. First, forget about the flywheel observation port to find top dead center. Also, forget about sticking a phillips head in the hole where your spark plug is and rotating the variator nut counter clockwise to align the two bolt heads on the camshaft's sprocket to the edge of the valve cover casing while watching to see that the screwdriver has pushed out to find top dead center.
While turning the variator nut counter clockwise (or the flywheel side clockwise) watch the tappet armature depress the spring on one valve to its most compressed down position, then adjust and tighten the OTHER valve. You will notice under the tappet that the cam lobe is pointing straight up and it is very easy to turn the variator nut then back and forth a little bit so that it of course must cause the cam lobe to compress the spring to its most pressed position while pointing straight up. Then adjust the other valve in the same way...observe the armature on the side that you just adjusted press the spring to its most pressed position with the cam lobe pointing straight up, then adjust and tighten the OTHER valve.
This positioning of 'top dead center' will quickly show you why many people have a hard time adjusting the valves to quiet them down. It adjusts for wear on the cams, it adjusts for poor factory spec alignments on the sprocket, and it adjusts for guessing where top dead center actually is which is an absolute must to correctly adjust the valves. Realize also that because of the relatively loose tolerances in gy6 motors.. that you simply cannot adjust both valves at once by using only one 'best guess' position of 'top dead center'. Each must be adjusted in accordance with the OTHER valve fully compressing its spring.
I will not get into what clearance to use because it will cause a firestorm of controversy. Go with factory recommended specs is my best advice there. However I will say that for high performance many agree that the intake should use a close tolerance (not shut tight but a thin shim feeler adjustment) and that the exhaust side should use a slightly thicker shim. THIS is where you will get the tapping sound (mostly from the exhaust side) that is tolerable and frankly necessary so you don't go around worrying that your valves are not tapping at all. You will notice after adjusting the valves in this way, that it is a tapping noise and NOT clacking.
In answer to your question. If you are asking how loud is too loud.. then you need to adjust your valves to closer tolerances because you will TOTALLY hear the difference then. I was frustrated beyond BELIEF until I learned this simple method of adjusting valves. When my cam lobes were in position to compress the spring to its max thus pointing the cam lobe straight up......my sprocket 'ALIGNMENT' bolt heads were WAY off !!!! I was completely losing sleep over WHY WHY WHY do my valves TAP SO FRIGGIN LOUD! It was because I had not adjusted my valves properly and they were way too loose.
The difference in sound is like night and day. You will be amazed.
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Post by scottish1 on Apr 3, 2011 10:32:51 GMT -5
p.s. valves must be adjusted when motor is cold as in overnight cold
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Post by pwr2wh8 on Apr 4, 2011 1:37:53 GMT -5
thanks for the tips! i'm going to try your method because using the tdc method seemed to have made my valves noiser.
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Post by sprocket on Apr 4, 2011 14:24:15 GMT -5
I have always set valves like scottish1 suggests. The TDC method is very error prone and doesn't take into account cam lobe wear, cam chain flex and generally poor can grinding. I have also found the cam sprocket keyway can be off as much as 3 to 5 degrees...
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Post by pwr2wh8 on Apr 9, 2011 0:33:40 GMT -5
i readjusted my valves using the scottish1's method and that made all the difference. my valves are quiet once again! i now highly oppose the tdc method.
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Post by Bluefront on Apr 9, 2011 5:18:52 GMT -5
There are obviously a number of ways to do this valve adjustment.....because there are times during the crank rotation cycle when each valve should be totally closed with each valve at it's maximum clearance, and not just at TDC on the compression stroke.
But I've always used the marking on the cam gear to determine TDC.....and adjusted each valve at that single point. I'm assuming the engine has the correct cam timing....if not, no amount of valve clearance adjustment will make the scoot run correctly.
Depending on how accurately the cam is ground, the valve clearances will vary somewhat at other crank positions, but it's the TDC position on the compression stroke that's most critical. At that point the spark plug fires, and at that point the valves have to be totally closed or you'll burn a valve/valve seat.
The other thing.....using the cam markings, you can be certain you'll have the crank at the same position each time you do the adjustments. If the valves prove to be too noisy at that point, you can recheck the valve adjustments at the same point of crank rotation you did the original adjustment. With other methods you may not be at the same rotation point where you did the original adjustment.
Anyway.....take your pick of adjustment methods. Most manuals specify using the TDC method for this procedure. That's how I do it.....YMMV
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Post by sprocket on Apr 9, 2011 11:29:32 GMT -5
Ya, well when the intake valve is fully open, it is really easy to see this. The rocker arm is fully depressed, then you adjust the other valve. It is so easy to get the engine in this position and it is 100% repeatable...then you reverse it
The TDC is OK if you are careful, but I have seen engines done this way, that are in fact way off in the gaps...
Different strokes...
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Post by Stash on Mar 29, 2012 19:25:50 GMT -5
I used this method after trying TDC a hundred times and its far easier. Im pretty new to scoots but am pretty mechanically inclined. This way was much simpler.
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Post by timber on Mar 29, 2012 20:31:57 GMT -5
I have always set valves like scottish1 suggests. The TDC method is very error prone and doesn't take into account cam lobe wear, cam chain flex and generally poor can grinding. I have also found the cam sprocket keyway can be off as much as 3 to 5 degrees... This is astoundingly correct, but yes, TDC doesn't allow for the normal wear and tear at all, good tip. |
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Post by cmv727 on Mar 29, 2012 22:35:53 GMT -5
For those of us who are not entirely confident.... are there any videos, or maybe pics, that show exactly how this method is done? That would be really helpful!
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Post by timber on Mar 30, 2012 0:28:40 GMT -5
For those of us who are not entirely confident.... are there any videos, or maybe pics, that show exactly how this method is done? That would be really helpful! Yeah there's youtube videos that show the valve adjusting process and how, but they all use the typical TDC method, shouldn't matter tho the process is the same, just ignore the parts about TDC. Here's a very good video if you can get past the guy's very mono-toned, lifeless sounding narration www.youtube.com/watch?v=s0K-ytyjOFg |
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