Piston to valve clearance

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hoganJr
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Re: Piston to valve clearance

#46

Post by hoganJr »

CYBORG wrote:When the piston is at TDC the valves are closed. They open 5-10 degrees of crank rotation before the piston reached TDC. The playdough idea will work ,but involves several removing and replacing of the head
thank you. That makes a lot of sense.

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ericheath
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Re: Piston to valve clearance

#47

Post by ericheath »

With the 1000 heads on the 1200, the intake was the one that would hit. The intake valve begins opening 5 degrees BTDC on the exhaust stroke. Advancing the cam will make it that much sooner. The ramps come into play as well. Clay is the only safe way. You could go by another 's results, but only if your sure your heads have never been shaved before.

I may go with 1100 heads and cams on my new 1200 project. Still debating with my ego, torque or hp? I will be able to drop in early cams without pulling the heads if I don't like it. I will just have to make sure the pistons are notched enough.
Whatever I suggest here should be given ample time for a moderator to delicately correct. I apologize in advance.
77 WING, 1200 engine with 77 heads, cams, gl1100 foot pegs, Magna V65 front end, 764A carbs, [-gone Suzuki M109 monoshock--, replaced with gl1100 shocks] gl 1200 swing arm, gl1500 final drive, wheel and rear brakes Valkyrie seat, Meanstreak tank, Sportster pipes, Power Arc ignition off crank.
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robin1731
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Re: Piston to valve clearance

#48

Post by robin1731 »

hoganJr wrote:
CYBORG wrote:When the piston is at TDC the valves are closed. They open 5-10 degrees of crank rotation before the piston reached TDC. The playdough idea will work ,but involves several removing and replacing of the head
thank you. That makes a lot of sense.

HoganJr

Now, you want to be really confused? Valve overlap. ;)
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robin1731
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Re: Piston to valve clearance

#49

Post by robin1731 »

CYBORG wrote:snip..........The playdough idea will work ,but involves several removing and replacing of the head

True, with the dial indicator you can move the cams around to where you have more or less clearance without taking anything apart. But, the cam timing can change enough to not be close to where you want it. Two to then gain clearance is to either notch the piston, or sink the valves in to the valve seat further.

Getting in to race engine building more here now. ;) lolol
1976 Goldwing Super Sport
1985 Honda Elite
1976 KZ900 Dragbike
1992 ZX7 Dragbike (KZ900 style motor w/NOS)
and a rotation of various purchases
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CYBORG
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Re: Piston to valve clearance

#50

Post by CYBORG »

Didn't want to confuse things with overlap :lol: :lol:
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Re: Piston to valve clearance

#51

Post by canuckxxx »

My mind is so boggled that I had to lay down confused22
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robin1731
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Re: Piston to valve clearance

#52

Post by robin1731 »

CYBORG wrote:Didn't want to confuse things with overlap :lol: :lol:

I like to see them squirm. lolol lolol shakehands :flamer
1976 Goldwing Super Sport
1985 Honda Elite
1976 KZ900 Dragbike
1992 ZX7 Dragbike (KZ900 style motor w/NOS)
and a rotation of various purchases
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CYBORG
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Re: Piston to valve clearance

#53

Post by CYBORG »

:2thumbs :happy_251: :happy_251: :happy_251:
1978 custom GL1000
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hoganJr
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Re: Piston to valve clearance

#54

Post by hoganJr »

robin1731 wrote:
hoganJr wrote:
CYBORG wrote:When the piston is at TDC the valves are closed. They open 5-10 degrees of crank rotation before the piston reached TDC. The playdough idea will work ,but involves several removing and replacing of the head
thank you. That makes a lot of sense.

HoganJr

Now, you want to be really confused? Valve overlap. ;)
Fascinating stuff. Is valve overlap as old as the ICE, or is it something that a specific engineer or design group developed?

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1991 GL1500
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CYBORG
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Re: Piston to valve clearance

#55

Post by CYBORG »

Again, valve overlap is a function of the cam. Is designed in by the engineers. The amount of overlap is partly needed due to the RPM of the engine, to account for the lag time of the valves changing direction. Put other factors come into play as well
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1985 gl1200
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Oldewing
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Re: Piston to valve clearance

#56

Post by Oldewing »

other factors,

1. rotation of the earth

2. amount of time between waves at Hilton Head

and lots of other spooky stuff..... lolol lolol
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CYBORG
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Re: Piston to valve clearance

#57

Post by CYBORG »

Spooky stuff indeed. But predictable :lol: :lol:
1978 custom GL1000
1977 custom with 1200 engine
1985 gl1200
Gator417
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Re: Piston to valve clearance

#58

Post by Gator417 »

Still going ahead with this project. Just got side tracked with so many other aspects of life. So I'll report back all of my findings as soon as I do the dirty work.
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ericheath
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Re: Piston to valve clearance

#59

Post by ericheath »

Just to feed your fire, some guy at Saunders in about the last year came on and claimed he shaved the heads 0.040. He didn't say if he notched Pistons or sunk the valves. He claimed some impressive numbers using different cams and dual webers iirc. I have another 1200 to get to. I was hoping this summer, but it's looking like next winter. I think I will try Robins suggestion of sinking the valves some and a thinner head gasket, unless I find a decent supercharger to use on it. Sunnbobb is getting closer on his Aisin and it looks to be a promising and less than $2500 supercharger.
Whatever I suggest here should be given ample time for a moderator to delicately correct. I apologize in advance.
77 WING, 1200 engine with 77 heads, cams, gl1100 foot pegs, Magna V65 front end, 764A carbs, [-gone Suzuki M109 monoshock--, replaced with gl1100 shocks] gl 1200 swing arm, gl1500 final drive, wheel and rear brakes Valkyrie seat, Meanstreak tank, Sportster pipes, Power Arc ignition off crank.
77 Wing. black
83 Wing, in pieces
"Continuing education is important even if the subject matter is fairly useless (as in this case)."---Greg Foresi
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