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Compression questions???

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Old Jul 14, 2017 | 12:18 AM
  #11  
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Originally Posted by 0ldhippie
Your cylinder cc measurements could be off, Or the intake cam could be off...
Thinking if the intake cam was off there would be a significant difference in one cylinder. The cylinders are 3.927.

I haven't taken anything apart since the build. New pistons and rings etc.... Had 0 deck height.
 
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Old Jul 14, 2017 | 12:28 AM
  #12  
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How is the play of the pushrods? Can you turn them by hand in TDC? If you can turn them too much it means they are too loose. Did you take your time when bleeding the lifters?How does the bike sound when you turn it over without plugs? You feel or hear any clicks ?
 
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Old Jul 14, 2017 | 01:14 AM
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Originally Posted by TomCop
How is the play of the pushrods? Can you turn them by hand in TDC? If you can turn them too much it means they are too loose. Did you take your time when bleeding the lifters?How does the bike sound when you turn it over without plugs? You feel or hear any clicks ?
Did the rear cylinder pushrods around 25 flats (s&s quickie). Went in the house about 30 minds and did the front. They bled down pretty good not to loose. Not much valve train noise at all. No clicking during the compression test just sounds like a big pump. Got even pressure in both cylinders. Was just expecting it to be more than 180.
 
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Old Jul 14, 2017 | 01:53 AM
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Originally Posted by bigpayback21
Did the rear cylinder pushrods around 25 flats (s&s quickie). Went in the house about 30 minds and did the front. They bled down pretty good not to loose. Not much valve train noise at all. No clicking during the compression test just sounds like a big pump. Got even pressure in both cylinders. Was just expecting it to be more than 180.
Just going through some stuff here: what cylinder head seals did you use, thicker one?
During the compression test the throttle was wide open? No air => No compression. Spark plug from other cylinder was removed during the test? I don't know the specs from yr Andrew cam, and if they required some removal of material from the cylinder cover to allow for free movement of the rocker arms. Which might reduce the air intake period. Now if both compressions are the same I should not be to worried about. Assuming that the piston rings and the overall installation has been done correctly of course. There are still loads of options to in crease the compression. For my build I run on 110 bolt on kit with MVA SE cylinder heads and high compression piston 10.5:1, with SE 263 cams for increases compression. I get 220 PSI during my compression test.
 
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Old Jul 14, 2017 | 02:40 AM
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Originally Posted by TomCop
Just going through some stuff here: what cylinder head seals did you use, thicker one?
During the compression test the throttle was wide open? No air => No compression. Spark plug from other cylinder was removed during the test? I don't know the specs from yr Andrew cam, and if they required some removal of material from the cylinder cover to allow for free movement of the rocker arms. Which might reduce the air intake period. Now if both compressions are the same I should not be to worried about. Assuming that the piston rings and the overall installation has been done correctly of course. There are still loads of options to in crease the compression. For my build I run on 110 bolt on kit with MVA SE cylinder heads and high compression piston 10.5:1, with SE 263 cams for increases compression. I get 220 PSI during my compression test.

I used the. 040 MLS gasket that came with the 106 kit. During the test I pulled both plugs and had WOT. The Andrews 57 cam had. 056 lift and doesn't require alterations to the rocker cover.
 
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Old Jul 14, 2017 | 07:52 AM
  #16  
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How does it run? Does it sound good and run good? If so I wouldn't think too much into it. You have the same compression on both cylinders, that's a good thing. Maybe your gauge is off or there is a slight leak in the gauge to cylinder fitting. If it's running good, don't sweat it. I did a 98" big bore on an 88" engine. I never checked compression. I never needed to, it goes like a raped ape and little to no oil comes out the breathers. The way I see it, no problems=no reason to check compression and try to over think it.
 
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