The Great Early Cams in a 1200 Debate

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Rednaxs60
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Re: The Great Early Cams in a 1200 Debate

#46

Post by Rednaxs60 »

ericheath wrote:So the 1000 gets about 9% more curtain area due to its 38mm intake valve to the 1200’s 36mm intake valve.

The 1200 gets 15% more curtain area on the exhaust side.

I wish I knew which is better and why, but my guess is the greater exhaust flow and more overlap helps pull more intake air in yielding a better low rpm performance.
Eric - went and had a look into this because inquiring minds want to know. Here is a web site regarding this: https://www.quora.com/What-is-a-%E2%80% ... p%E2%80%9D

According to the article, you are spot on with a little extra clarification. There is a host of articles for this, but your short answer is good enough for me. I think the optimizing of the air charge in the cylinder according to the article only suits the original design intent, don't know what it will do when used as a mod to another engine design. Won't remember what I've read or found until I need it at a later date.

Cheers
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1985 GL1200 Limited Edition
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1995 GL1500 SE CDN Edition (sold)
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ericheath
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Re: The Great Early Cams in a 1200 Debate

#47

Post by ericheath »

A little more gas on the fire, or water, depending on....

Another difference in 1200 heads is the exhaust spindles are drilled slightly closer to the valve face than the intake spindle, hence an explanation as to why it has more lift on the exhaust.
5DE2CDC7-C408-4975-A43C-747333DBCA3E.jpeg
5DE2CDC7-C408-4975-A43C-747333DBCA3E.jpeg (126.47 KiB) Viewed 72 times
Lines are drawn free-hand with editing program. You can see what I mean.

Had a wild hair thought from desertrefugee because Valk’s are solid rockers, but they are all the same whereas the early wings used an A and B rocker arm which is offset more.
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
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